Pregnancy is a physiological process in which a fertilized egg, first called an embryo and later called a fetus, develops in the uterus. The duration of pregnancy is about 9 astronomical or 10 obstetric months. Traditionally, the development of pregnancy is considered by trimesters. However, knowing how the embryo develops week by week is also of interest.

Embryo or fetus?

In medical science, you can often find two concepts related to the period of gestation - “embryo” and “fetus”. What's the difference between them?

Intrauterine development of the fetus is conventionally divided into two stages:

1. Embryonic – lasts the first eight weeks. At this time, the embryo that develops in the uterus is called an embryo.
2. Fetal (from 9 weeks until the moment of birth). At this stage, the fetus resides in the mother's womb.

How the child, his internal organs, systems, will develop during various periods of intrauterine development of the fetus is determined by the genetic code that was transmitted by the germ cells of the mother and father.

1-10 weeks

1 Week

Speaking about the first week of pregnancy, you should clearly understand what exactly is taken as the starting point. If we talk about obstetric weeks (regardless of whether there is a multiple pregnancy or not), then we take into account the first day of the last menstruation of the cycle when the woman had unprotected intercourse and, accordingly, conception occurred.

Sometimes the moment when contact occurred without the use of contraceptives is taken into account. By counting by days, you get the third obstetric week. If we take into account the date of the start of the delay in menstruation, we get the fifth. In gynecology, when analyzing the intrauterine development of the fetus by week, they often focus on obstetric timing.

The first few days, even if it is a multiple pregnancy, are not characterized by any clear signs. This time is the beginning of the menstrual cycle. The level of hCG (human chorionic gonadotropin) is within normal limits (5 IU/ml for non-pregnant women).

HCG fluctuations at the first stage are evidence of:

• previous abortion or miscarriage;
• taking hormonal drugs.

2 week

This time is marked by the fact that the zygote continues to mature in the uterus or fallopian tube, which, under favorable circumstances, will become a developing pregnancy.

Towards the end of this period, there comes a time when, after conception, the egg attaches to the wall of the uterus.

This can be indicated by discharge that is similar in consistency to egg white and even bloody. Small discharges of blood are relative evidence of the attachment of an egg to the wall of the uterus and the appearance of an embryo. Heavy discharge during this period of pregnancy is not the norm.

3 week

It was at this time that it can be argued that conception occurred. The fruit is extremely small, its size is 0.15-0.2 mm in length, and its weight is only 2-3 mcg. If fertilization does not occur, the woman may begin her period several days earlier. When maintaining a special calendar, it is easy to notice a slight shift.

If the pregnancy was planned, significant bleeding may indicate a threat of miscarriage.

4 week

The embryo develops so actively that a woman may begin to feel the first signs of her changed status, especially if the pregnancy is multiple. There is swelling of the mammary glands, the nipples become sensitive. Menstruation is delayed, and scanty bleeding is sometimes observed.

At this time, there is an increased risk of fetal developmental abnormalities due to excessive physical activity, an infectious disease accompanied by high fever, and abuse of alcoholic beverages.

HCG levels only increase in the blood. On an ultrasound, you can see the corpus luteum, which provides nutrition to the embryo before the placenta begins to fully function, and is also involved in the production of progesterone, the so-called pregnancy hormone.

The size of the embryo increases. It is already 5 mm in length.

The fruit weighs 3.5 g and length is from 4 to 7 mm. The rudiments of limbs, fingers, eyes, ears, slits for the nose and mouth, and some glands and systems begin to form. The size of the uterus changes.

An ultrasound specialist at this time can tell whether a woman is developing a multiple pregnancy or whether she will have one child. During the examination, the diameter of the amniotic sac is determined, as well as the coccygeal-parietal size and the “growth” of the fetus. The last digit will appear in the results throughout the first trimester.

Changes in the body become more noticeable. Some women note a slight increase in body temperature to subfebrile levels. However, if the condition begins to fit the description of a cold, you should immediately consult a doctor.

week 6

The woman begins to show signs of future motherhood. The uterus reaches the size of a plum - an experienced gynecologist is able to feel it during the examination. If there is a multiple pregnancy, an ultrasound will show two fetal and yolk sacs. The examination will also allow you to see small tubercles - here, over time, the upper and lower limbs will appear, and you can also hear the heartbeat using a special device. Facial features gradually emerge. The embryo reaches a length of 4-9 mm, its weight is no more than 4.5 g.

week 7

The fetal heart becomes four-chambered and large blood vessels are formed. The first trimester is marked by the continued development of all internal organs and systems. Weight – 1 g, coccygeal-parietal size is 13 mm. The unborn child gradually begins to straighten up. The brain is developing rapidly.

The face and upper limbs are improved. The umbilical cord completes its formation and a mucous plug forms.

The size of the fruit increases significantly - 14-20 mm in length, it begins to move. By the middle of the first trimester, the face acquires more and more human features. The formation of organs and systems has been completed, some of them are actively functioning. The optic nerve is born, the rudiments of the genital organs appear.

Week 9

The coccyx-parietal size of the unborn child reaches 22-30 mm, weight - 2 g. The cerebellum, pituitary gland, middle layer of the adrenal glands, lymph nodes, and genitals are actively formed. The functioning of the cardiac and nervous systems is improved. The upper and lower limbs begin to move, bend, and muscles appear. The fetus gains the ability to urinate.

The critical first stage of development ends for the fetus. Weight reaches 5 g, and height – 30-40 mm. The heart rate reaches 150 beats per minute. The limbs are fully formed, you can see the joints and fingers. The foundation of baby teeth is laid, which obliges the mother to keep a food calendar and mark the consumption of dairy products in it. Most of the gastrointestinal tract organs have already completed their formation.

11-20 weeks

11 week

The critical stage of development is virtually over. The weight of the fetus reaches 8 g, the “height” is 5 cm. From this moment, the embryo enters the fetal stage. The heart is working fully, the formation of blood vessels is completed. The placenta becomes dense. The liver occupies 10% of the body. The intestines make the first movements similar to peristalsis.

The genital organs are increasingly formed. Eye color is determined and the sense of smell appears. Palms and fingers become sensitive.

12 week

Critical moments for fetal development depend more on the health and lifestyle of the mother. The body length ranges from 6-9 cm. The unborn child already has fingers and nails are forming. The gastrointestinal tract organs are completing their formation. The immune system is improved.

The first trimester ends, the critical cycle is completed. The baby teeth are fully formed, muscle and bone tissue continues to form, and the digestive system develops. The genital organs are differentiated. The child’s “height” reaches 8 cm, weight – 15-25 g.

Week 14

The baby is actively growing and developing. Its weight is 30-40 g, and its height is from 8 to 10 cm. The resemblance to a person is increasing. In case of multiple pregnancy, the expectant mother can feel the movements of the children, who are becoming more and more active. The bone skeleton grows, ribs are formed. The movements of the diaphragm resemble breathing. All organs and systems are fully formed. The child has an Rh factor and blood type.

Starting from the 15th week, the baby’s cerebral cortex begins to form. The process will take most of the second trimester. The endocrine system, sebaceous and sweat glands are activated.

Taste buds are fully formed, breathing movements are improved. The baby’s weight reaches 70 g, from the tailbone to the crown it is already as much as 10 cm. But even with multiple pregnancies, this does not interfere with free movements.

Week 16

By the first half of the second trimester, the baby is already 11 cm tall and weighs 120 g. The neck has taken an even position, the head rotates freely. The ears and eyes gradually rise upward. The liver takes over digestive functions. The development calendar is becoming busier. The composition of the blood is completely formed.

The immune system turns on, interferon and immunoglobulin are produced. The baby is able to protect itself from infections coming from the mother. But they all continue to be critical for the small organism. The fetus develops a layer of fat. If a girl grows, by the middle of the second trimester she will have a uterus. A person's height is 13 cm, weight is 140 g. He is able to hear sounds from the outside and feel emotions. From the point of view of emotional and mental development, week 17 is critical - establishing contact is extremely important.

The second trimester is approaching the middle. The upper and lower limbs of the fetus, phalanges of the fingers, and prints on them are fully formed. Fat tissue, the immune system and the brain continue to actively develop at week 18. The rudiments of molars are formed.

A reaction to light appears, and hearing increases. The calendar must include the date of the first movements and their frequency. Fetal height is 14 cm, weight – 200 g.

There is a big leap in development. Movements become more orderly. The respiratory system is improving. The body is covered with vernix. By week 19, the head rotates freely and is held in one position. Weight reaches 250 g, and height – 15 cm.

Week 20

The child is already fully formed, his organs are improving. By week 20, the heartbeat can be heard with a regular stethoscope. The limbs are fully formed. The sensations of sounds become more acute. The length is 25 cm, and the weight is about 340 g. The movements are more noticeable for the mother.

21-30 weeks

By 21 weeks, the baby gains height - 26.7 cm and weight - 360 g. But there is enough room for active movements. The digestive system works more actively, the fetus constantly swallows amniotic fluid. Muscle and bone tissue are strengthened. The spleen is involved in the work of the body.

Week 22

The period is marked by a significant increase in weight - up to 500 g. Height also changes - as much as 28 cm. The fetus at these times is viable even if it is first born. The brain and spine are fully formed. Reflexes are improved. The heart increases in size.

Week 23

By the 23rd week the fetus is sufficiently formed, the digestive system is fully functioning. Adipose tissue accumulates. The genital organs are clearly differentiated.

The baby's height reaches 29 cm, and his weight is 500 g. The spleen becomes more active.

Externally, the fetus already looks like a child. Due to the small amount of adipose tissue, the weight is only 600 g with a height of 30 cm. By week 24, independent production of growth hormone begins.

The respiratory system enters the final stage of development. Reflexes and sensory organs are improved. A sleep and wakefulness pattern is developed. The baby begins to listen to the mother’s emotions. The movements become sensitive.

The fetus gained weight to 700 g and grew to 34.5 cm. The resemblance to a newborn increases.

The lungs are preparing for the first independent breath. The hematopoietic function is completely carried out by the bone marrow.

The sense of smell is highly developed, the child senses the mother’s mood swings. The bone skeleton is actively overgrown with muscles. Testicles and vagina appear.

The fruit acquires individuality. The eyes begin to open. The child is able to recognize the voice of his mother and father. Bone tissue is strengthened. The lungs are finally taking shape. The brain produces various hormones. The baby weighs 750 g and is as much as 36.5 cm long. He sleeps 16-20 hours. Movements can be noticed by others.

Week 27

The fetus weighs 900 g by 27 weeks. Growth becomes more active. The endocrine system also enters a new phase of activity. The stability of a child’s pancreas determines the development of metabolic processes and mental abilities. The production of surfactant, a substance that allows the lungs to open after birth, stabilizes.

The amount of subcutaneous fat increases. The mother feels the baby’s training even more strongly.

Bone tissue continues to strengthen. Alveoli appear. The future little man can weigh 1 kg or more. Having reached 38.5 cm in height, the baby begins to feel a lack of free space in the uterine cavity, although this does not in any way affect his activity.

Week 29

The baby's body is gradually preparing for the upcoming birth. Thermal regulation and the functioning of the immune system are improved. The blood composition has been stabilized. The digestive system is completely ready to digest food. The gaze begins to focus. The skin gradually brightens and loses wrinkles. Subcutaneous fat increases, muscle tissue strengthens.

Week 30

The child’s weight reaches 1500 g. Gradually the nervous system “turns on.” The liver accumulates iron. The work of the heart acquires sexual differentiation - in boys it beats more calmly than in girls. Typically, by this time the fetus is in the position from which it will be born. Movements become calmer. Eyes open.

31-40 weeks

The child may already weigh more than 1.5 kg. The liver acquires the ability to cleanse the blood.

Surfactant production continues. The connection between peripheral nerve cells and the brain is established. Having touched the cornea, the baby will definitely close his eyes. The calendar of intrauterine development is gradually ending.

Week 32

The active growth phase continues. Organs and systems are fully functioning. The skin and appearance take on a familiar appearance. Lanugo, the original down, gradually disappears.

The baby is finally in position for birth. The skull remains soft.

At this time, the weight reaches 2000 g. Muscles and subcutaneous fat continue to build. Body parts become more proportional, many body systems work fully. The child is able to express emotions. The kidneys are prepared for their main function - filtration.

34 week

Fetal development is coming to an end. Individual traits become more and more obvious. Gastrointestinal tract training is more active.

By these days, organs practically do not develop. Activity is observed in terms of building muscle and fat tissue. Every week the baby gains up to 220 g. The skin is deprived of lanugo and completely smoothed out. Shoulders are rounded.

The body continues to improve. Iron continues to accumulate in the liver, and vital systems are being adjusted. The baby actively sucks his thumb in preparation for the upcoming breastfeeding. Most children occupy, that is, head down.

Week 37

The fruit is fully formed. The gastrointestinal tract is ready to receive and digest food, peristalsis is activated. Heat exchange processes have been established. The lungs are ripe. Iron accumulates in the liver. Height and weight increase weekly.

The baby is ready to be born. In male children, the testicles descend into the scrotum. The skin takes on a pink tint.

The fetus is fully formed, its organs and systems are ready for independent functioning. Reaction to sounds and light is developed. There is no original lubricant on the surface of the skin.

Week 40

The baby's height is approximately 54 cm, weight - from 3 to 3.5 kg. The formation is completely completed.

Future mothers are sensitive to the development of the baby they carry under their hearts and want to learn as much as possible about the processes happening to them during pregnancy , study with interest the stages of intrauterine growth of the fetus, carefully examine the pictures that depict in detail fetal development by week.

Gynecologists begin counting the pregnancy period from the first day of the last menstruation. Basic unit of time pregnancy- a week.
The first weeks for the unborn child - are very important, at this moment the health of the body and its vitality are formed.
It's good if pregnancy will be planned , then the woman will begin to lead a correct lifestyle and will protect the baby from many health problems. Below you will find detailed information about the formation embryo in the womb, you can consider the development of the fetus week by week - Pictures with all stages of intrauterine growth and development, as well as a description of the processes occurring at one stage or another of pregnancy.

Before turning to the photo with the stages of fetal development by week, let’s briefly familiarize ourselves with the main periods of formation of the organs of a little person during pregnancy. At 5-6 weeks, an embryo measuring 6 millimeters in size (like a pear seed) lives in a bladder with liquid. The formation of the nervous system occurs, the spine and brain appear. Two pairs of dimples for the eyes and ears are visible on the head. Digestive tract begins already at this stage of fetal development.

Only 2 weeks pass and the main internal organs of the fetus are already formed. In the eighth week of fetal development, the face takes on the necessary shape, the nostrils, the tip of a small nose, mouth, and tongue are noticeable. Begins to function inner ear . The fingers of the developing baby are also emerging.

12 weeks fetal development- the age of a ten-centimeter embryo in which the outlines of a human body are visible. At the twelfth week of fetal development, various systems and organs have already formed and are developing safely. Modernized ultrasound equipment allows you to find out the sex of the baby and see facial features at this stage of pregnancy.

The beginning of the second trimester of pregnancy is the period of fetal development when all the baby's milk teeth are formed. The gastrointestinal tract also develops at week 13, villi appear in the intestines , which in the future will speed up the process of digesting foods.

Up to the 21st week of fetal development, the size of the baby allows it to move in the womb in any direction. The length of the fruit is 26 centimeters, weight is 0.4 kilograms.

The little body is able to control its temperature from 29 weeks , the period of preparation for the birth of a baby and independent life begins.

At 31 weeks of development, the body is fully formed, all that remains is to gain weight. The child is already able to feel, his condition can change depending on the mother’s mood. Hearing is developed enough to recognize voices. Vision and smell also function.

The baby is ready to be born at 37 weeks. Now the birth cannot be called premature. Of course, ideally you need to wait a little. But the baby can already absorb and digest mother’s milk , epithelium with villi appears on the mucous membrane of the stomach and intestines, through which Nutrients pass from food into the blood . Peristalsis is working, the first feces - meconium - have formed.

Now let's take a closer look fetal development by week of pregnancy, and also turn to the photo of the formation of the embryo in the womb with brief explanations. As you can see, very important processes in the formation of the structure of the fetus take place already in the first weeks after conception, and the expectant mother needs to seriously change her lifestyle and adjust her diet from the first days . Visit your gynecologist regularly and undergo all necessary medical examinations.

Even pictures with stages of intrauterine development of the fetus by week clearly demonstrate the importance of the ongoing processes of formation of the baby’s internal organs. We hope that the information we post will help you better understand the processes what happens in your body during pregnancy and we want to wish you that the baby was born healthy and beautiful !
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Embryo. The developing human body in the period before birth.

Human intrauterine development normally lasts 280 days. During this time, from two cells fused together, a new, completely unique person is formed, capable of living separately from the mother’s body.

The science that studies the development of the embryo is called embryology. Knowledge of how the human embryo develops is very important for doctors, especially those who work in obstetrics and pediatrics. Ideas about the normal course of embryo development processes help to accurately and timely detect the occurrence of pathologies in developing embryos, look for the causes of infertility and solutions to this problem, create contraceptives, and implement measures that will prevent serious pathologies of fetuses and newborns.

Periods of human development during pregnancy

Human development during intrauterine life (or embryogenesis) goes through several stages.

• The union of parental germ cells that serves to form a zygote.
• Division of the resulting zygote to form a blastocyst.
• Development of germ layers and the start of the formation of all organs (gastrulation).
• Development of various organs and tissues (histo- and organogenesis).
• Systemogenesis (formation of organ systems).

In another way, human intrauterine life is divided into three very important periods: fertilization with the formation of one cell (zygote), embryonic and fetal periods.

The embryonic period begins from the second week after fertilization until the end of the eighth week of embryo development (before the end of the tenth week of obstetric pregnancy).

The beginning of the ninth week of human intrauterine development (eleventh week of obstetric period) marks the beginning of the fetal period (fetal period). From this moment on, the developing person is no longer called an embryo, he is called a fetus.

Fertilization is a complex union (fusion) of two reproductive parent cells. The process involves one egg and approximately 300 million sperm, of which only one will be the “winner”. As a result of this process, the diploid set of chromosomes (that is, 46 chromosomes) is restored. At the moment the parent cells unite, the sex of the developing person is determined. A new cell is formed ─ zygote.

Fertilization in humans occurs in the fallopian tube, in its ampullary part. There are several stages of fertilization:

• Interaction of germ cells at some distance and their approach.

During this phase of fertilization, the egg releases substances that attract sperm. They become capable of fertilization under the influence of a special secretion produced in the female genital tract.

• The germ cells come into contact and the egg is activated.

It rotates, and the acrosomal reaction starts. The result of this is an increase in the permeability of the sperm membrane.

• Penetration of the male reproductive cell (sperm) under the membrane of the mother cell, fusion of the parent cells.

After this, a fertilization membrane is formed on the surface of the fertilized egg, which prevents the penetration of other sperm.

Embryo implantation day

On the 7th day after conception, the embryo implants into the endometrium. This process is called implantation, it is very complex. The duration of embryo implantation is slightly less than two days (about 40 hours). Then the actual embryonic period of development begins.

A woman may not yet know about her pregnancy, but a new life is already developing in her body. Many women have suspicions about their pregnancy when menstruation does not arrive on time. The expectant mother sees only two lines on the pregnancy test display, and the embryo already has its first heartbeats.

This indicates the special importance of the embryonic period of development. The woman’s body and the unborn child are very sensitive to environmental fluctuations, the effects of infections, radiation, toxins and drugs during this period.

Knowledge of how an embryo develops day by day and week by week during its intrauterine life helps to understand the timing of the formation of certain organs, the mechanism of formation of congenital malformations of embryos, which can even lead to spontaneous termination of pregnancy. Based on the information obtained, critical (dangerous) periods concerning the development of the human embryo and fetus were identified. The period from 3 to 8 weeks of embryonic life is designated critical in human ontogenesis.

Fetal period of human development

The fetal period in human ontogenesis starts from the ninth week of embryo development, starting from the moment of fertilization. The obstetric gestational age is two weeks longer than the actual period of embryo development. The fertile period ends with the birth of a person. Then comes the newborn period.

Starting from the 11th week of obstetric pregnancy, the developing person is called a fetus. It is almost completely formed, all organs are formed and active tissue differentiation is underway. The fetus is connected to the mother's body through the formed placenta.

Although the formation of all organs has already been completed by this period of fetal development, several critical moments of the fetal period differ. Thus, from the 15th to the 20th week of pregnancy, the brain grows rapidly. And from 20 to 24 weeks of gestation, the functional systems of the body develop, and the genitourinary apparatus differentiates.

The study of the complex mechanisms of how the human embryo develops after conception continues to this day. The science of embryology describes how an embryo develops day by day in the first week of its life. Embryology further describes how the embryo develops week by week after fertilization (first trimester).

Starting from the second trimester of pregnancy, the description of embryo development by week corresponds to the obstetric period of pregnancy. This means that the gestational age is not counted from the moment of expected fertilization, but from the first day of the last menstruation, which is approximately 2 weeks longer than the embryonic period of development.

Changes in embryo development by day are of particular importance in the first week of embryo development after fertilization. What characterizes the development of an embryo day by day at the very beginning of its intrauterine life?

1-2 days

After the nuclei of the parent cells unite, a zygote is formed. It begins to divide by mitosis into cells called blastomeres. At first the zygote divides slowly, then faster.

Blastomers are formed of two types: “dark” and “light”. “Light” cells line up in one layer around the “dark” ones, from which the trophoblast is formed. It is the link between the embryo and the mother’s body and provides it with nutrition. From the “dark” blastomeres, the embryoblast begins its formation ─ the precursor of the body of the human embryo, as well as its extra-embryonic organs.

3-4 day

After the formation of the zygote, a dense cluster of blastomeres forms a morula. On days 3-4, a blastocyst is formed - a vesicle with a cavity. Within three days, the blastocyst moves through the fallopian tube directly into the uterine cavity. At this time, embryo- and trophoblast cells continue their differentiation. The size of the embryo at this stage is up to 0.2 mm.

5-6 day

The blastocyst remains free in the uterus for two days. The trophoblast cells of the blastocyst provide the embryo with nutrients from the breakdown products of the mother's tissues. Embryoblast cells are located in a nodule at one of the poles of the blastocyst, which is attached to the trophoblast from the inside. The embryo is preparing to attach to the wall of the uterus.

Day 7

On the 7th day after conception, the embryo is implanted into the mucous membrane of the uterine cavity, that is, it is introduced into it. Embryo implantation occurs in two stages:

1. Attachment of the embryo to the endometrium.
2. Direct implantation of the fertilized egg into the uterine mucosa.

Trophoblast has the ability to secrete enzymes that promote the attachment of the embryo to the inner layer of the uterus. After this, the fertilization membrane is destroyed.

From the second week, the actual embryonic period of development begins. It continues until the end of the eighth week of development (until the end of the tenth week of obstetric pregnancy). The human embryo does not stop developing even for a second. For convenience and ease of understanding, this period of human development is divided into weeks. How does an embryo develop week by week during pregnancy?

Embryo development at 2 weeks

The amniotic sac is formed from some of the blastocyst cells. This occurs by day 8 of embryo development. By the 11th day, the chorion is formed. This villous membrane of the embryo is the precursor of the placenta. Up to 12 days, the process of implantation of the embryo, which began several days earlier, continues, and the process of gastrulation begins.

Gastrulation continues from day 13. This is a very complex process in which the tissues of the embryo grow and differentiate, resulting in the formation of germ layers: ecto-, meso-, and endoderm. From some of the cells of the blastocyst, the primary streak is formed, from which the head process of the embryo is formed. The embryonic notochord (future spinal column) begins to develop from it.

Vessels and blood cells begin to form in the embryo (hematopoiesis). In addition, there is a growth of blood vessels in the chorion area. The formation of the first blood cells occurs in the yolk sac. At this stage, the embryo is connected by a stalk to the placenta, which has begun its formation.

After 15 days from the day of conception, the embryo reaches a size of 0.4 mm. It forms a notochord, a perichordal plate. The embryo itself has a three-layer structure.

The embryo at 17-19 days of development has a length of about 1-1.5 mm. It is shaped like a pear with a widened head end. The thickening of the ectoderm forms the neural plate, and from it the neural groove. The tissues of the nervous system of the embryo begin their development from the neural groove. Blood vessels and cells develop further.

At the age of 19-21 days, the human embryo stretches. The cephalic end of the embryo at this stage is wider than the caudal end. Mesoderm compactions are detected. Secondary chorionic villi are being formed. In addition to hematopoietic cells, endothelial cells are identified in the yolk sac; they will subsequently become the internal lining of arteries and veins.

By the end of the 3rd week of embryo development, the heart is formed. It looks like two tubes, separate for now. A bud is formed, but it is soon reduced.

Embryo development at 4 weeks

The size of the embryo at the beginning of the 4th week of its development varies from 1.5 to 2.5 mm, but towards the end of this week it reaches 5 mm in length. The embryo at this stage is shaped like the letter “C”. First, a neural groove is formed, which then closes into the neural tube. In the head part of the embryo there are already nerve cells, the rudiments of ears and eyes.

The previously separated tubes, which were the predecessors of the heart, are closed. The first heartbeats can be recorded, blood flow begins in different parts of the embryo’s body. In the middle of the 4th week of intrauterine life, septa and valves are formed in the fetal heart.

The epithelial tissue of the digestive tube gives rise to the digestive organs (liver, pancreas), and the trachea, esophagus and lungs begin to form from the epithelial tissue of the pharyngeal intestine.

By the end of the 4th week, the embryo is curved in a semicircle and is located in the amniotic sac. The rudiments of the arms are formed, the anlages of the legs are noted. Skin epithelium is being formed. Bones and muscles begin to form.

The head part of the neural tube is differentiated and three brain vesicles are formed. An auditory vesicle is formed, and the lens of the eye is formed. You can detect the primary oral cavity (bay) and the rudiment of the tongue. The thyroid gland is forming, the respiratory and digestive organs are actively developing, and primary kidneys are being formed.

The umbilical cord is formed; it connects the vessels of the placenta and the liver, which at this time is located in the head part of the embryo.

The size of the embryo at the 5th week from the day of fertilization is 5-7 mm. It is arched and has a noticeable cervical curve. The arms lengthen, the formation of the hands and innervation of the upper extremities begins.

There is intensive growth of the heart and brain, which is divided into parts: anterior, posterior and middle. The spinal cord is differentiated, the anterior lobe of the pituitary gland actively develops and grows, and the lens of the eye improves.

The esophagus becomes clearly visible, which gradually separates from the trachea. On both sides of it are the lungs. The heart has four chambers and its valves form. The permanent kidney and bladder are being formed.

Embryo development at 6 weeks

At week 6, the embryo measures between 7 and 13 mm in length. In the first days of the 6th week, the embryo develops a primary face and the outer ear is formed. The embryo's eyelids close and the nasal pits are identified. The fetal brain enlarges and the formation of spinal nodes occurs. The deepening of the oral cavity grows towards the intestinal tube. The digestive tube increases in length, and growth of the esophagus is noted. The kidneys develop progressively. Segments are identified in the arms of the embryo. The feet and their innervation begin to form. Throughout the week, the embryo develops rapidly, the face and sensory organs change noticeably.

An embryo at 6 weeks is distinguished by the fact that its back gradually straightens and ossification of the skeleton is initiated. The muscles of the face and lower jaw appear. The auricles are identified and the pituitary gland is formed. Pigment forms in the eyes and the eyelids grow together. The formation of the rudiments of teeth and olfactory bulbs is underway. An embryo at 6 weeks has well-formed arms, although the hands are not yet fully developed.

The development of the respiratory organs is in full swing. The heart has 4 chambers, the pulmonary artery separates from the aorta. The diaphragm is forming. The embryo's intestine is directed into the umbilical cord, which is called a physiological hernia of the embryo. The liver and pancreas develop. The gonads are populated by germ cells, which are still primary. The development of the genital organs begins. The kidneys produce the first urine.

Embryo development at 7 weeks

The size of the embryo at the 7th week of intrauterine life ranges from 17 to 28 mm. Its shape resembles an arc. The formation of the tissues of the skull and face is underway. The lower jaw is well visualized, but the upper jaw is not yet clearly defined. Fingers are forming on the hands, segments are visible on the feet, and the development of the feet is underway.

The two hemispheres of the brain are clearly distinguished, and the development of the hindbrain begins. In the abdominal cavity, the mesentery is clearly visible, in which arteries, veins, nerves, and lymphatic vessels are identified. There is an elongation of the ureters, which are directed from the kidneys to the developing bladder.

At 8 weeks of development, the embryo is approximately 25 to 40 mm. By the beginning of the 8th week, the embryo's head straightens. He has well-developed eyes, which are still located on the sides of his head. The ears are low and the nostrils are formed. Convolutions are noticeable in the hemispheres of the brain. The structures of the inner ear are being formed.

The skeleton is actively developing, the back is lengthening, and skeletal muscles are developing. Arms bent at the elbows cross over the stomach. The places of large joints are indicated on the legs, the toes are distinguished, although there are still membranes between them.

At 8 weeks after fertilization, the embryo begins to make its first movements, which are still involuntary. In the heart, a septum develops between the atria. By the end of the 8th week, the critical period of heart formation is completed.

The tongue is almost formed, taste buds and teeth are developing. The bones of the hard palate fuse. The intestine that previously exited into the umbilical cord returns to the abdominal cavity. The genital organs, both external and internal, are actively developing. The sex of the child becomes discernible. The anal membrane is perforated. Tail degeneration occurs.

With the introduction of ultrasound diagnostics (ultrasound) into medical practice, future parents have the opportunity to look at their child long before his birth. According to pregnancy management protocols, the first ultrasound is performed at an obstetric gestational age of 10-14 weeks (8-12 weeks of embryonic development). This study coincides with the collection of venous blood from the expectant mother for testing.

All these activities are called screening during pregnancy.

To view the embryo on an ultrasound scan before this period, there must be indications. For example, suspicion of an ectopic pregnancy, preparation for termination of pregnancy, the appearance of some pathological symptoms in a woman, suspicion of a frozen pregnancy.

Some people do an ultrasound of the embryo just out of curiosity, but such a risk is not justified. Currently, there is not enough information about how safe ultrasound of the embryo is and how many times it can be done during the period of gestation.

What does an embryo look like on an ultrasound?

At 3-4 weeks of embryonic development, the embryo is still too small to clearly see body parts or emerging developmental defects. At this time, the expectant mother will see only a bright spot and the first heartbeats on the monitor. But we can say with confidence whether the embryo is located in the uterus.

By the end of the 7th week, an ultrasound scan of the embryo can distinguish the head, torso, limbs, and formed umbilical cord. The embryo itself has a characteristic curved shape.

By the end of the 8th week of embryonic development, according to ultrasound data, you can already obtain a lot of information about the embryo and see some developmental defects, if any. For the mother, parts of the embryo’s body, some organs, and active heartbeats become visible on the ultrasound monitor screen.

To perform a high-quality ultrasound of the embryo, transvaginal (through the vagina) and transabdominal (through the anterior abdominal wall) scans are used.

Is it possible to take a photo of the embryo?

More than 50 years ago, people first saw an embryo in a photograph. These unique photographs, reflecting human development at different stages of pregnancy, starting from the moment of fertilization, were taken by photographer from Sweden Lennart Nilsson. To capture the embryo in a photo, he used modern photographic equipment, a light guide and a cystoscope. Thanks to him, the whole world saw such a mysterious intrauterine life of a person. These photos of embryos are still very popular, they play a big role in the fight against abortion in early pregnancy at the request of women.

Modern parents can see their child during an ultrasound examination. Ultrasound equipment allows you to take a photo of the embryo, obtaining a two-dimensional or three-dimensional image.

There are a huge number of infertile marriages in our country. There are more than 15% of them. In total, there are officially more than 5 million married couples in Russia whose marriage has been declared infertile. Moreover, both female and male infertility is increasing. More than 2.5 million couples require assisted reproductive technologies.

The basis of assisted reproductive technologies is the classical method of in vitro fertilization (IVF) and embryo transfer (ET) into the uterus.

What is IVF (in vitro fertilization)?

In vitro fertilization (IVF) is a method of artificial fertilization of eggs taken from women with male sperm, which is previously centrifuged and processed in a nutrient medium. Oocytes (eggs) are also cultured on nutrient media. Subsequently, the resulting embryos are implanted into the uterus.

In most cases, in vitro fertilization uses the germ cells of the spouses. Donation of eggs (oocytes) and embryos is used when it is impossible to obtain a woman’s own reproductive organs or when they are inferior. Sperm donation is used at the request of a woman in the absence of a spouse, as well as in the case of a spouse who has sperm that are not capable of fertilization.

There are the following types of IVF:

• IVF itself and transfer of the resulting embryos.

The egg is fertilized with sperm outside the female body, then the embryo is implanted in the uterus.

• ICSI (from ICSI - IntraCytoplasmic Sperm Injection) is an auxiliary IVF method.

A special feature is that an IVF embryo is formed as a result of the fusion of an egg and a sperm, which was introduced under the shell of the mother cell using a special microneedle. The method is used for various qualitative and quantitative pathologies of male germ cells.

There are situations when, after several unsuccessful IVF attempts, it is possible to achieve pregnancy only by using the ICSI method.

In addition, surrogacy is highlighted, in which an embryo after IVF develops in the uterus of a volunteer woman. After birth, the child is passed on to its genetic parents.

Indications for IVF

The following indications for in vitro fertilization are distinguished:

• Infertility in a woman, which is caused by obstruction or absence of the fallopian tubes.
• Inability to conceive, the cause of which has not been established.
• Infertility that cannot be treated, or that is easier to overcome with IVF than with other methods.
• Infertility caused by immunological problems (detection of antisperm antibodies).
• Male infertility, which requires the use of the ICSI method.
• Some diseases of the female reproductive system (endometriosis, polycystic ovary syndrome).

Contraindications to IVF

The list of contraindications for IVF and embryo transfer is very wide:

• Various deformations of the uterine cavity, in which the attachment of embryos is impossible.
• Neoplasms of any location in the body (even if it happened in the past).
• Tumors of the uterus that are benign; tumors of the uterine appendages.
• Inflammatory processes at any localization.
• Other diseases of internal organs that prevent pregnancy.
• Some mental disorders.

At the preparatory stage for IVF, spouses undergo numerous examinations and undergo various tests in order to identify indications and contraindications for the procedure. Couples whose spouses are over 35 years old must consult a geneticist.

Once the couple is prepared for the IVF procedure, they will have to go through the following stages:

• Stimulation of superovulation in women with hormonal drugs. This is necessary for the maturation of several eggs at once. As the menstrual cycle progresses, the process of follicle maturation and the condition of the inner layer of the uterus (endometrium) are monitored. There are different schemes for stimulating superovulation; the choice is made individually.
• Obtaining female germ cells by puncture of ovarian follicles.
• Receiving your spouse's sperm.
• Fertilization of eggs with sperm or introduction of sperm into the cytoplasm of eggs.
• Transferring embryos into the uterus and monitoring the effectiveness of the process. If necessary, maintenance hormonal therapy is prescribed.
• Diagnosis of pregnancy.

How to obtain biological material for IVF?

The biological material for obtaining an embryo is eggs and sperm.

• Egg retrieval

This procedure is done under general anesthesia in sterile conditions. When receiving biological material, a woman is placed in a regular gynecological chair. The egg retrieval process is controlled by ultrasound. The cells are collected by puncturing the ovarian follicles with a special needle inserted through the vagina. If it is not possible to obtain eggs this way, then the eggs are collected using laparoscopy.

• Sperm collection

The sperm is collected on the same day as the eggs. You can obtain sperm through masturbation or withdrawal (using a condom without lubricant or spermicide). If a man has ejaculatory disorders, sperm are obtained by puncture of the epididymis.

After the collection procedure, the germ cells are sent to the embryology laboratory, where they are cleaned of impurities. Sometimes the in vitro fertilization procedure is carried out immediately (no later than 6 hours after receiving the material). In other cases, biological material is frozen. Freezing has virtually no effect on the viability of germ cells, but it allows you to save time during subsequent IVF attempts if the first ones are unsuccessful.

For fertilization, germ cells are placed in special containers with nutrient media. The containers are placed in an incubator, the conditions in which are close to natural. After a few hours, the sex cells fuse together. If this does not happen, then the sperm is introduced artificially into the cytoplasm of the egg.

After the procedure, the fertilized eggs are monitored. Those that divide well can be used for IVF. Excess fertilized eggs can be frozen (cryopreservation) and used for repeated IVF attempts (if necessary).

An embryo after natural conception is no different from an embryo after IVF in its structure, physiology and stages of further development. However, the germ cells used for IVF are often defective compared to those during natural conception. Including for this reason, after IVF there is a higher risk of congenital pathologies and chromosomal abnormalities in the unborn child. Some signs of these problems can be noted in the embryo by ultrasound or by the results of preimplantation diagnostics.

Why is preimplantation diagnostics of embryos needed?

Preimplantation diagnostics of embryos during IVF is carried out in order to obtain information about whether the unborn child has serious genetic pathologies. This is done before it is time for the embryos to be implanted.

The use of this method of examining human embryos has led to a reduction in the number of spontaneous abortions to 13% after pregnancy as a result of IVF in those couples where one of the parents is a carrier of genes that cause chromosomal abnormalities in comparison with couples who have similar problems, but who did not use preimplantation diagnostic services.

Identifying chromosomal abnormalities in embryos before transferring them into the uterus not only makes it possible to obtain healthy offspring, but also reduces the number of IVF attempts and reduces the risk of spontaneous abortion.

How many embryos are transferred into the uterus during IVF?

There are recommendations according to which you should not implant more than four embryos into the uterus. Firstly, multiple pregnancies are fraught with complications. Secondly, the reduction of excess embryos is also not a harmless procedure. In our country, as a rule, two embryos are transplanted into the uterus.

On the day when the embryo is transferred into the uterus, its development period reaches approximately 3-5 days. The stage of embryo development at this stage is blastocyst. Studies have been conducted indicating that it is at the blastocyst stage that the embryo in the uterus takes root best. The embryo already has a trophoblast, which is needed for implantation.

Less often, embryo transfer is carried out on the third or second day of embryonic life, or 7-8 days after fertilization. The decision is made individually in each specific case. The timing of embryo transfer depends on how many eggs were fertilized and how many of them continued their further division.

The size of the embryo on the day of transfer to the uterus

On the 4th day of its existence, the embryo measures about 0.14 mm, on the 6th day ─ 0.2 mm, by the end of 1 week of life ─ approximately 0.3 mm.

How is an embryo transferred into the uterus?

During the transfer of embryos to the uterus, the expectant mother is on a gynecological chair. The procedure requires the same sterility as for any other operation.

First, you need to insert gynecological speculum into the vagina. A thin, flexible catheter is then inserted into the uterus through the cervical canal, through which the embryos are transferred.

How does a woman feel during embryo transfer?

Women preparing for in vitro fertilization want to know in advance what they will experience during embryo transfer.

During the embryo transfer procedure, the woman is conscious. The sensations during embryo transfer are comparable to those during a routine gynecological examination (insertion of speculum). Some describe the sensations during embryo transfer as mild discomfort.

To avoid unpleasant sensations during embryo transfer, a woman is advised to relax, tune in to a good outcome of the procedure, and do not need to strain her abdominal muscles.

Upon completion of the procedure, you need to rest and lie down for a couple of hours. After IVF, you can return home from the clinic the same day. It is advisable that the woman have accompanying persons. At home you need to relax and not worry.

The embryo transfer procedure performed does not guarantee that pregnancy will occur. Whether the IVF process was effective can be judged after the embryo implantation is completed.

Embryo attachment after IVF usually occurs 7-10 days after the day of ovulation (2-3 days immediately after IVF).

On the day of implantation of the embryo into the endometrium, slight bloody discharge from the vagina may appear. They are due to the fact that implantation of embryos leads to damage to the mucous layer of the uterus.

During the days of expected embryo implantation, some women describe some symptoms: slight pain in the lower abdomen, drowsiness, weakness, dizziness, metallic taste in the mouth, slight increase in temperature. Whether these symptoms are related specifically to embryo implantation is unknown.

In order for the day of embryo implantation to be successful, a woman must adhere to some rules: eat rationally, limit exercise, do not lift heavy objects, refrain from taking a bath, wear loose clothes. Compliance with medical recommendations on diet, rest and physical activity allows you to achieve good results on the day of embryo implantation.

A reliable sign that embryo implantation has been successful will be an increase in the level of human chorionic gonadotropin (hCG) in the mother’s bloodstream.

Embryo reduction after IVF

Typically, IVF involves the development of several embryos. Two embryos are usually transferred into the uterus. If it turns out that more than three embryos are developing in the uterus, then an operation to reduce embryos from the uterus (removal of excess ones) is indicated. This forced measure is necessary for a normal pregnancy with twins or triplets.

The method of embryo reduction during IVF has good grounds; it is constantly being improved, allowing the couple to obtain healthy offspring. This is explained by the fact that carrying three or more fetuses in the uterus threatens miscarriage and the birth of very premature children.

Removal of excess embryos was initially performed through the cervix. The underlying fertilized egg was removed in the first trimester of pregnancy. However, this method of removing a human embryo turned out to be very traumatic and many complications followed.

Currently, other methods of embryo reduction after IVF are used: transvaginal (through the posterior vaginal fornix) and transabdominal (through the anterior abdominal wall). The intervention is carried out under the control of special equipment. The principle of the procedure is that a long needle is inserted into the uterine cavity, its tip is brought to the chest of the embryo that needs to be reduced. Then, using a needle, the organs of the embryo's chest are destroyed until the heart stops.

Features of pregnancy after IVF

The course of pregnancy after in vitro fertilization has its own characteristics.

• High risk of miscarriage in the early stages of embryo development (25-30% of all pregnancies after IVF), non-developing pregnancy.
• Increased risk of developing infectious and inflammatory diseases during pregnancy.
• Many pregnancies after IVF are multiple. This creates an increased burden on a woman’s body while carrying a baby. In this regard, chronic diseases may worsen more often, gestosis may occur, placental insufficiency and metabolic disorders may occur.
• Some women experience isthmic-cervical insufficiency (weakness of the cervix). There is a higher risk of having premature and low birth weight babies.
• Birth of children with congenital malformations and chromosomal abnormalities. This may be due to “inferior” reproductive cells of the parents.

After IVF, the birth of children is possible both through the natural birth canal and by caesarean section. Considering the high risk of multiple pregnancies and the presence of various concomitant pathologies in the mother, cesarean section after IVF is performed for most women. Other factors that may influence the choice of method of delivery are: the age of the mother, the duration of the period of infertility, gestosis during pregnancy, and the condition of the fetus. Be sure to take into account whether the woman has given birth before and how the children were born.

The process of childbirth or cesarean section in itself after in vitro fertilization is no different from that of conceiving an embryo naturally.

Complications of IVF

Like any intervention in the human body, IVF has its complications:

• Sometimes allergies occur to medications that are used to stimulate the ovaries.
• After IVF, various inflammatory processes and bleeding may occur.
• The risk of multiple pregnancy is high.
• The occurrence of ovarian hyperstimulation syndrome, in which the ovaries increase in size and cysts form in them. This condition is accompanied by various vascular and electrolyte disorders, problems in the blood coagulation system, hormonal imbalance and other serious pathologies.
• Sometimes the development of the embryo after IVF occurs outside the uterine cavity (the frequency of ectopic pregnancies varies from 3 to 5%).

Efficiency of IVF

The effectiveness of in vitro fertilization varies from country to country. Not all pregnancies that occur after implantation of embryos into the uterus develop successfully and end in childbirth. Many pregnancies are terminated in the first trimester. On average, only every fourth woman gives birth to a baby after IVF.

“Congratulations, you are pregnant!” – doctors used to say these words more often; with the advent of express pregnancy tests, they can be read in the instructions for the test. In any case, most women call pregnancy and motherhood the most amazing time in their lives.

It is not without reason that they say that a pregnant woman seems to glow from within; she is especially beautiful and attractive during this period. Of course it's a miracle! The expression is a little hackneyed, but, in fact, when a new life arises from a lump of mucus during 40 weeks of pregnancy, there is no other way to call it

Pregnancy is a physiological state of the body. The changes that are taking place are programmed by Mother Nature. These changes are so significant that because of them, a woman’s whole life switches to a new rhythm: about 80% of women feel nausea, especially in the morning; the perception of odors is heightened, some of them cause unpleasant sensations, including severe nausea and vomiting; the usual diet may change - your favorite food may cause disgust, and dishes that were previously on the list of hated foods may appear in first place; increased fatigue; an incomprehensible drowsiness is annoying; frequent urge to urinate; sudden changes in mood; tearfulness.

How pregnancy begins and develops

Fertilization

Each time in the middle of the menstrual cycle, one, rarely several, follicle matures in the ovaries. The follicle contains an egg. The moment the egg is released from the follicle is called ovulation. After release, the egg is picked up by the fallopian tubes and slowly moves towards the uterine cavity. If during this short (3-6 days) period of time a woman has sexual intercourse without means of preventing pregnancy, pregnancy may occur. The egg produces special substances that signal the sperm about where it is. If the “rendezvous” takes place, fertilization occurs. Pregnancy begins.

Fertilization occurs in the fallopian tubes, even before the egg enters the uterine cavity. After the fusion of the egg and sperm, a zygote is formed, from which the growth of the embryo begins.

What happens and what does the embryo look like? How will the size of the embryo change over the weeks? What changes will occur during the process of growth and development? What do photos of an embryo look like by week? Ultrasound is used to observe how the embryo develops over weeks and months.

Embryo 1 week

The zygote is still in the fallopian tube on its way to the uterus. The fallopian tubes are lined with villi, which move the egg towards the uterus. If the zygote does not enter the uterus within a certain time, it may attach to the wall of the fallopian tube. In this case, they talk about ectopic pregnancy - a condition dangerous to health and life.

During fertilization, the sperm brings in its 23 chromosomes, which combine with the 23 chromosomes in the egg. Moreover, depending on whether the sperm contains an X or Y chromosome, the gender of the unborn child depends.

After fertilization and the formation of a zygote, about 30 hours pass. The fertilized egg begins to divide. This process is called crushing, since with a slight increase in volume, the number of cells grows exponentially and their size decreases. From 1 you get 2, from 2 you get 4, etc. With an increase in cell mass, the gastrula turns into a morula. The morula looks like a spherical collection of cells. By day 7 after fertilization, the morula turns into a blastula. A fluid-filled cavity, or blastocoel, appears in the center of the embryo. The blastula enters the uterine cavity and is immersed in the mucous layer. This process is called implantation and involves the outer shell of the blastula, called the trophoblast. After implantation, trophoblast cells begin to produce human chorionic gonadotropin, an important hormone that supports pregnancy. Human chorionic gonadotropin can be detected in urine, where its presence is determined using a rapid pregnancy test. By the end of the first week, the size of the embryo is only 0.3 mm.

Embryo 2 weeks

On days 8-9 after fertilization, the blastula turns into a gastrula. In this case, the internal cells of the blastula are divided into 3 layers. The outer layer, or ectoderm, will develop into the nervous system and skin. The internal (endoderm) will turn into the cavity of the gastrointestinal tract. The mesoderm, the middle layer, will give rise to the musculoskeletal system (bones, ligaments and cartilage), muscles, kidneys, blood vessels and other internal organs. 10 days after fertilization it is already possible to get a positive pregnancy test result.

Embryo 3 weeks

At week 3, the embryo moves from the gastrula stage to the neurula stage. The ectoderm in the area of ​​the future spine forms a groove that gradually goes deep into the embryo. The edges of the groove are closed. A neural tube has formed that will become the brain and spinal cord. An embryo is formed that will become the baby’s heart.

At week 3, the placenta begins to form - the life support system of the embryo. The trophoblast and part of the ectoderm form the amnion and chorion. The amnion is popularly called the “shirt”. Amniotic fluid collects in the amniotic cavity. The chorion is a villous formation that also produces human chorionic gonadotropin. After some time, with the participation of the mesoderm, the placenta is formed from the chorion. By the end of 3 weeks, the embryo grows to a size of 4 mm.

Embryo 4 weeks

At week 4, the brain and spinal cord begin to form from the neural tube. At the same time, the heart makes its first contraction. Now it will not stop until the very end of life.

The rudiments of arms, legs, eyes, and internal organs are formed. Blood begins to flow in the blood vessels. Before this, the embryo received nutrients from the yolk sac, which, like in birds, contains reserves necessary for the initial stage of development. In addition, the yolk sac in mammals plays the role of the liver, bone marrow, and kidneys. It is the yolk sac that contains future germ cells, which migrate from it to the primordia of the gonads. After the appearance of the corresponding organs in the baby, it gradually disappears by the end of the first trimester.

Embryo 5 - 6 weeks

Embryo. 5 weeks from the moment of fertilization.

At 5 weeks, the umbilical cord is formed, which will connect the baby to the placenta. The umbilical cord contains arteries and veins. The length of the umbilical cord by the end of childbirth can reach 70 cm. At the 5th week, the arms and legs look like flippers, but individual details can already be distinguished. The first impulses begin to be generated in the nervous system - the basis of nervous activity. The head of the embryo is formed, and holes for the ears, eyes, mouth and nose appear in it. The length of the embryo reaches 1 cm.

Embryo. 6 weeks from the moment of fertilization.

At week 6, it is already possible to distinguish the features of the future face. Limbs and fingers are developing. The baby begins to make his first movements. The pigment that determines the color of the eyes is formed on the iris. At week 6, the embryo's heartbeat can be seen and heard using an ultrasound scanner or ultrasound. The placenta is fully formed. The rudiments of the lungs, kidneys, gonads, stomach and intestines are formed. Amniotic fluid already surrounds the embryo. The 6th week of pregnancy in Western countries is considered the optimal time for the first visit to a gynecologist. It is necessary to do an ultrasound, undergo a series of tests, and undergo an examination by specialized specialists.

Embryo 7 weeks

At week 7, the embryo's tail disappears. The gill slits close and become overgrown. Lungs begin to form. Limbs lengthen. The external genitalia and lymphatic vessels develop. The brain is enlarged. The heart is almost completely formed. The tip of the nose and eyelids are already visible. The size of the embryo reaches 1.5 cm.

Embryo 8 weeks

The kidneys begin to produce urine. Hair follicles form in the skin. Almost all vital organs have already been formed. Reflexes and feelings are triggered. Ears form, the face no longer looks like an alien from a science fiction movie. It is clearly visible that a person is growing. The bones are still made of cartilage, but later they will be saturated with calcium and turn into real bone tissue. This process will be completely completed only by the age of 25, long after birth. The size of the embryo is almost 2 cm.

Embryo 9 weeks

Now the baby can shake his fist if something worries him - his fingers can clench into a fist. The process of blood cell formation is transferred to the liver. The intestines unfold and fit into the abdomen. You can clearly see the ears, eyelids, nose, mouth and eyes. The face is fully formed. The rudiments of teeth are formed. The baby is already 3 cm tall and growing quickly.

Embryo 10 weeks

The baby's eyelids close. He will open them himself at 28 weeks. The respiratory system is almost completely formed. The skeleton and its structure fully correspond to a person. The arms and legs are lengthened to normal proportions. But the head occupies almost half the length of the body. This is due to the active development of the cerebral hemispheres, the cerebellum is growing. The external genitalia develop according to gender. You will soon find out if he or she is growing in your belly. The baby's blood acquires its own group and Rh factor. Height can reach 7-8 cm.

Embryo 11 weeks

The baby has a hairstyle. The fine hair on the head and body is called lanugo. They usually fall out by the time of birth. The skin is almost transparent, blood vessels are visible. The first foci of ossification form in the bones. White blood cells - leukocytes - appear in the blood. The arms are pulled up to the face, the baby can put a finger in the mouth. We begin to do exercises - the baby can actively move in the womb, but its size (10-15 cm) and low weight (30 g) do not yet allow the mother to properly feel these movements.

Embryo 12 weeks - 13 weeks

Embryo 12 weeks. Photo

During this period, you can visit a doctor and have an ultrasound examination done in 3D reconstruction mode. Here is your baby's first portrait. Ultrasound can determine the sex of the child with almost 100% accuracy. During an ultrasound, screening for developmental pathologies is carried out. The finger can now be sucked - the sucking reflex has appeared. The liver and pancreas produce secretions. Meconium is formed in the intestines - original feces. The formation of the genital organs is completed. The baby's height is about 15 cm, weight 40-50 g. Despite the fact that the child is so small, he is already a person. All organs are in their places, now his body will be more resistant to negative influences. All that remains is to grow. The first trimester is over.

Embryo 14 weeks -15 weeks

Eyebrows and eyelashes grow on the face. Now the baby’s face can express emotions - developed facial muscles allow him to make faces, cry, and grimace. Sweat and salivary glands appear. The heartbeat can be heard using an obstetric stethoscope.

Embryo 16 weeks -19 weeks

Marigolds appeared on my fingers. Taste buds on the tongue can sense taste, and receptors in the nose can sense smell. Mom may or may not like the foods she eats. Fully formed ears make it possible to hear sounds. Including mom's heartbeat. Recent research has led to an original practical application - soft toys are made for newborn children that reproduce the mother's heartbeat. It is believed that a calm, measured heartbeat calms the baby. Try not to be nervous. The eyes begin to discern light.

And of course, during this period, mothers begin to feel the baby’s movements inside them. There is feedback from the mother. The baby can sleep and be awake, this is noticeable by periods when no movements are felt. Baby's height is 20 cm and weight is up to 250 g.

Embryo 20 weeks -30 weeks

Did you feel the kick? Now the baby communicates with his mother this way. If mom is sad, upset about something, or there is loud music around, it’s smoky, stuffy, the baby violently expresses his opinion. At first it’s timid, but by the end of pregnancy this method of communication will no longer cause tenderness. Constantly getting kicked from the inside can be quite painful. A sudden noise or fright of the mother leads to a similar response from the child. Protective reflexes arise.

In the lungs, the formation of respiratory alveoli is completed. Fingerprints form on hands. Brain development occurs at the fastest rate. Neural connections are formed. The baby can blink. The immune system is formed. The respiratory organs are developed enough to provide breathing in the event of premature birth, but sometimes only with medical assistance and special equipment. Adipose tissue appears. By 30 weeks, growth reaches 40-43 cm, weight up to 1.5 kg.

30 weeks - 38 weeks

Childbirth is approaching. The baby turns head down in preparation for birth. Vellus hair disappears, with the exception of the shoulders. The lungs actively produce a substance called surfactant. It is necessary for breathing atmospheric air, protects the respiratory sacs and prevents them from sticking together. Without surfactant, the lungs may not expand fully. In premature babies, this is the main cause of oxygen deficiency and death. By the time of birth, the baby will be 52 cm tall and weigh about 3 kg.

Childbirth occurs on average at 38 weeks from conception, but doctors usually measure gestational age in obstetric weeks, from the date of the last menstrual period. In this case, 38 weeks of intrauterine development is equal to 40 obstetric weeks. Embryology, the science that studies the development of the embryo, considers a child to be an embryo from conception to birth. At 38 weeks, the embryo develops in the uterus. But, from 13 weeks, the embryo, for the convenience of doctors, is already considered a fetus. From the 13th week of development, the embryonic period passes into the fetal period. This is also related to legal aspects.

Bearing and giving birth to a child is a difficult ordeal for any woman. But the delight and joy of motherhood are many times greater than any other feelings. There will be sleepless nights, and great anxiety at moments when the baby is sick, and worries. Kindergarten, school, adult life and the child’s problems will always come first for you. After all, you are now connected forever.

We will tell you in detail what will await you from the beginning of the birth of a new life until the very birth.

Pregnancy is a special time that changes the expectant mother’s worldview, her values ​​and priorities. Almost every woman faces certain difficulties while carrying a baby. To avoid them, it is important to have complete information about all the processes occurring in the female body at each stage of pregnancy.

Early pregnancy: first month

Most women do not even realize that they are pregnant, while very serious changes are beginning in their body. Pregnancy becomes known only at the end of the first month, and sometimes at the beginning of the second.

Doctors consider the beginning of pregnancy from the beginning of the last menstruation, although fertilization usually occurs after ovulation. Therefore, the concept of “obstetric period” is several weeks longer than the actual gestation time.

Changes in a woman's body

The first and second weeks of the month are the time when a woman is not yet actually pregnant, but her reproductive system is actively preparing for conception. In the first week, menstruation occurs as usual. If you are just planning to become a mother, then you should stop taking analgesics for menstrual pain: the chances of successful conception will be higher. In the second week, one of the eggs begins to mature.

By the beginning of the third week, at the moment, the strongest egg leaves a special bladder filled with liquid into the fallopian tube. Here the female reproductive cell will remain for several days, waiting for fertilization.

The so-called yellow body will begin to form. It will be responsible for the hormonal levels that are optimal for the development of pregnancy.

All that is needed now is fusion with the sperm. Two cells, connecting with each other, form a zygote - the future embryo. The zygote is miniature in size and moves freely throughout the uterus, only after a few days attaching to its wall.

To maintain the vital functions of the zygote, the mother’s body produces large amounts of progesterone. Because of it, a woman will feel heaviness in the lower abdomen and pain in the nipple area, as with PMS. The urge to urinate will become frequent, drowsiness and sensitivity to odors may occur.

Baby development at 1 month

During this early period, all the genetic information that shapes your baby’s appearance, character traits and predisposition to diseases is laid down.

The sex of the baby is also determined. There are two types of sperm: one carries the XX chromosome, the other carries the XY chromosome. The sex of the child will depend on which of them can get to the egg. If fusion occurs with the XX sperm, a female embryo will begin to develop; If XY sperm enters the fallopian tube, the couple will have a boy. By the end of the 4th week of pregnancy, the embryo has already completed its attachment to the uterine cavity and enters the embryonic stage.

The level of the hormone will increase, and now pregnancy can be determined using a simple pharmacy test.

Three areas are formed in his body, which will later become full-fledged organs and systems. Also this week, the formation of the chorion (future placenta) and amnion (fetal membranes) is completed. And your baby is still very small - the size of the embryo is only 0.5 millimeters.

1. It is necessary to undergo an ultrasound scan as soon as there is a suspicion that conception has occurred. This will help to diagnose an ectopic pregnancy in a timely manner.
2. At this time, taking vitamins A and E is useful. Also, all pregnant women are prescribed folic acid for the proper development of the fetus.
3. A complete abstinence from tobacco, alcohol and junk food is required. The expectant mother needs to walk in the fresh air as much as possible and get pleasant emotions.

Second month of pregnancy: changes in a woman’s body

At this time, the fact of pregnancy is already clearly established. There is a delay in menstruation, there should be no discharge. Any discharge with bloody impurities indicates the danger of embryo rejection, and in this case a visit to the doctor is required.The first signs of early toxicosis appear. It is especially expressed in morning nausea and vomiting.

Problems arise in the gastrointestinal tract: heartburn, belching, constipation. These phenomena will stop only by the end of 3 months.

A serious test will be changes in psychological terms. Your family should be sensitive to mood swings. But a pregnant woman should also try to control herself, because nervous tension is not good for you or the baby.

The development of the corpus luteum reaches its peak, and by the end of this month the uterus will grow to the size of a large orange and can be easily palpated during examination.

Due to sprains, a woman may experience a pulling sensation in her sides and lower back.

Together with progesterone, lactogen, a hormone responsible for the development of the placenta, begins to influence the body. Their action reduces protein synthesis while increasing the production of glucose and fatty acids. This is necessary to compensate for energy expenditure on fetal development.

Baby development at 2 months

During this month, all organs and systems of the baby take their place. By the 5th week, his heart will make its first beats and blood vessels will appear. The organs of the respiratory and excretory systems will be formed. The brain is already beginning to respond to primitive reflexes.

The embryo still has a small tail, making it look like a small tadpole. The rudiments of facial features will appear on the fetal head: nose, eye sockets, ears.

In boys, the penis and testicles are identified. Now your future baby has moved from the embryonic stage to the fetal stage. Its physical dimensions are about 2.5 cm.

Seventh and eighth months of pregnancy

There is less and less time left until the moment of birth. Expectant mothers are going on maternity leave and are in search of a good obstetrician and maternity hospital. It is also worth deciding whether you want your husband to be present during the birth.

Feelings of a woman at 7 and 8 months

The production of the hormone relaxin increases, preparing your muscle ligaments for childbirth. Because of this, back pain appears, and it becomes more difficult for muscles and joints to stay in good shape. Your gait may become a little awkward, varicose veins become worse, and urinary incontinence may occur.

Also, the action of hormones increases the growth of body hair. After childbirth, they should disappear, so there is no need to deal with excess hair now.

By the end of the 8th month of pregnancy, the belly increases to almost its maximum size. Now the height of the uterine fundus will be up to 40 cm. Training (false) contractions begin, causing no pain at all. They prepare the uterus for real labor.

In many pregnant women, the nesting reflex is activated. You will increasingly want to devote time to making your home comfortable; willy-nilly, you give preference to viewing and reading materials for pregnant women.

Baby development at 7 and 8 months

Your baby has become very big, he is getting more and more cramped in the uterus. The fetus occupies a position that will remain until birth. If the presentation is unfavorable, you can perform special exercises to help “turn over” the baby.

All basic reflexes have already been formed. Bones are strengthened and the calcium content in them increases significantly. The lungs are completely ready to take the first breath.

By the last week of the 8th month of pregnancy, the fetus will weigh twice as much as at the end of the second trimester - 2.5 kg.

1. The most dangerous thing that can happen now is the development of gestosis. If you have a headache, swelling has increased and your blood pressure has risen sharply, it makes sense to go to the hospital immediately.
2. Once every two weeks you will visit the doctor and get tested. A full examination is required: measurement of the uterine fundus, fetal heartbeat.
3. Swimming will help reduce the feeling of heaviness. They have a relaxing effect on the muscles and also calm the nervous system.

Ninth month of pregnancy: woman's feelings

You've reached the finish line! Although there is anxiety before childbirth, this month is the easiest for many mothers. It will literally become easier for you - your stomach will drop, which means the pressure on all internal organs will decrease.

Now your weight difference with the “pre-pregnancy” state is from 8 to 16 kg. The belly will no longer increase; on the contrary, visually it may become smaller. This happens due to depletion of amniotic fluid. You will experience for yourself what the harbingers of childbirth are. They will appear several weeks before labor (sometimes the warning signs appear several days before contractions). Among them are increased false contractions and the release of mucus plugs.

The problem of constipation disappears, but with pressure on the bladder, a constant urge to urinate begins to arise.

Fetal movements are noticeable less and less.

Your psychological attitude also changes. You will be characterized by slowness and absent-mindedness. Changes in mood are a consequence of anxiety before childbirth. Give free rein to your emotions, have fun or cry. Communicate more with your loved ones in the last weeks before the maternity hospital, because it is so important for you to feel their care.

Baby development at 9 months

The baby takes its final position, in which it will pass through the birth canal. His skin has a light tint, the fluff disappears, and the cheese-like lubricant remains in the folds of the body. The bones of the baby are quite hard; there is a fontanelle between the sutures of the skull. It will heal soon after birth. Thanks to the fontanelle, it will be easier for the baby to be born - the bones of the skull will be in a free position.

The child is completely ready for life outside the mother's womb. The lungs are ready to expand upon birth, the heart adapts to work in a new rhythm.

In the intestines of a newborn there is original feces (meconium), consisting of remnants of substances from the amniotic fluid.

1 In the last week of pregnancy, the mother needs to be very careful. It will be difficult for you to move, so you should walk with support if possible. Walk on stairs holding the railing tightly.

2 Labor can begin at any time. You should always have your personal doctor's number handy.

Do not leave the house for a long time, or even better, take a walk only in the company of close people. Always carry with you a package of documents necessary for the maternity hospital.

3 Start packing your bags for the maternity hospital in advance at the beginning of the month. This way you will be sure that you have not forgotten anything important in a hurry.

So, the difficult time of pregnancy has come to an end. Now comes a new period, full of completely different worries and joys. Keep a positive attitude and you will definitely become the best mom!

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