Photographs of human embryos at various stages of pregnancy. Formation of the fetus by week of pregnancy. Fetal development by week
From the moment a woman finds out about pregnancy, she begins to listen to her body every day, trying to catch the slightest changes and understand what is happening to her unborn child. If we are talking about in vitro fertilization, then increased attention to one's feelings begins even earlier. How does the embryo develop by week? We list the most characteristic processes at all stages of its development in vitro and in utero.
After their successful fertilization by conventional IVF, or the development of embryos begins. On a daily basis, this process looks like this:
- Zero day: actual fertilization.
- First day : the presence of male and female nuclei in the embryo is assessed.
- Second day: the formation of a zygote by the fusion of the female and male genomes; the beginning of the division of the embryo and the assessment of its quality in terms of fragmentation, size and shape.
- The third day: the embryo consists of 4-8 blastomeres (daughter cells).
- Fourth day: there are at least 10 blastomeres (ideally 16), the surface of the embryo becomes smoother - the so-called compaction process occurs; henceforth it is called morula. With natural conception, it is at this stage that the embryo passes from the tube into the uterine cavity.
- Fifth and sixth days. The embryo is called the blastocyst, which consists of two types of cells. The blastocyst is covered with a shiny membrane that ruptures; only then is the embryo capable of implantation.
- Seventh day. With successful hatching (the exit of the blastocyst from the shell), implantation occurs.
Stages of embryo development
Back in the 1960s, photographer Lennart Nilsson, using a powerful lens, was able to take a photo of the development of the embryo by weeks. By and large, this process is the same both with natural conception and if in vitro fertilization was used. Only the initial stages of intrauterine development differ. We list the main stages of embryo development by weeks after IVF:
First trimester
The first trimester is the most important in the formation of the embryo, since it is during this period that the laying of organs occurs.
Second trimester
14-15 weeks. Eyebrows and eyelashes appear, the baby can make facial movements, the musculoskeletal system is strengthened. The heartbeat increases so much that it can be heard using an obstetric stethoscope. The pancreas begins to produce insulin, the genitals change (for example, a prostate gland forms in boys).
16-19 weeks. Nails appear on the fingers, the sense organs are improved, the ears begin to hear, and the eyes begin to distinguish light. The size of the fetus increases so much that the mother feels it move; the composition of the blood becomes more perfect.
20-25 weeks. During this period, coordination of movements improves; all women begin to feel fetal movements. Bones are strengthened.
third trimester
26-30 weeks. The formation of alveoli in the lungs ends, which produce the substance (surfactant) necessary to maintain their shape. The baby actively reacts to loud sounds, can blink. The brain develops rapidly, adipose tissue begins to form, the skin becomes elastic. By this time, the child becomes practically viable.
30-38 weeks. The skin becomes smoother, the child gains weight, the work of internal organs improves. Closer to the time of birth, the baby changes position, turning head down (not always, but in most cases).
Development of the human fetus
Fruit Size Chart
The weight and height of the fetus are one of the most important parameters that help determine how well its intrauterine development proceeds. To track these criteria, with some allowable errors, allows ultrasound, as well as standard measurements of the size of the uterus and abdominal circumference. The table below shows the average values that the doctor is guided by when assessing the development of the fetus.
Ultrasound diagnosis, or ultrasound, is a mandatory procedure during pregnancy. This is written in the law. Now that you can see how pregnancy develops from the inside, there is nothing surprising, but even 25 years ago, in the current post-Soviet space, such a fact would have been bewildering. Only in the mid-90s of the last century, expectant mothers got the opportunity to find out if everything is in order with their unborn child, and doctors - the opportunity to control pregnancy and anticipate possible fetal pathologies.Ultrasound during pregnancy is carried out using a special apparatus, which, with the help of ultrasound hitting a special sensor platinum, displays an image of the fetus and its membranes on the screen. Recently, the so-called 3D ultrasound has become widespread, its peculiarity lies in the fact that a three-dimensional image is displayed on the screen, the smallest details of the appearance of the unborn baby are visible. In the early stages of pregnancy, ultrasound is performed by the vaginal method, later - by the abdominal method, that is, through the abdominal wall.
Two ultrasound diagnostics during pregnancy are mandatory. The first is carried out for a period of 11-13 weeks, the second - 17-20 (21) weeks. In the normal course of pregnancy without pathological conditions, two ultrasounds are enough. The third ultrasound is performed in the middle of the third trimester, but more recently only by indications.
Mothers wait with special trepidation for every ultrasound, so there is nothing surprising in the fact that pregnant women often undergo more than the prescribed diagnostics. Let's talk about what can be seen on ultrasound at each stage of pregnancy.
Ultrasound: 1st week of pregnancy
Experts count the gestational age not from the day when the conception occurred, but from the first day of the last menstruation. Therefore, the first week of pregnancy is not yet pregnancy, but the active preparation of the body for it. Now on ultrasound, you can see that the uterine cavity is somewhat enlarged, because menstrual blood and dead endometrial cells accumulate in it. Small antral follicles are visible. at this time, a natural decline in the hormone estrogen occurs in the woman's body, due to which the follicle-stimulating hormone (FGS) “forces” several follicles to mature.
Photo ultrasound 1 week of pregnancy
Ultrasound: 2nd week of pregnancy
Now the ultrasound will show the dominant follicle, the diameter of which can be 17-30 mm. Just before ovulation, you can see a special tubercle in it - the process of egg maturation takes place in it. The mucous membranes of the uterus at this stage become thicker.
Photo ultrasound 2 weeks pregnant
Ultrasound: 3rd week of pregnancy
Ovulation occurs and the egg follows into the fallopian tubes, where it looks for the most "successful" sperm. Now comes the pregnancy. However, the ultrasound machine is not able to see the future embryo, as it is still too small. The third week of pregnancy is critical, because due to a lack of hormones, the body can start menstrual bleeding again, which will “wash away” the fertilized egg.
Ultrasound: 4th week of pregnancy
At this time, ultrasound already detects the presence of pregnancy. It is a small black circle, the diameter of which is only a few millimeters. This is a fetal sac. Ultrasound diagnosis at the fourth week of pregnancy notes the expansion of the vessels of the uterus. This is the norm.
Ultrasound: 5th week of pregnancy
Now the unborn child is an oval with a tail and a head. At this stage, ultrasound already clearly sees it. Doctors already call it an embryo. The heart, spinal cord and brain begin their active development. Ultrasound captures distinct contractions of the emerging heart. However, this is not yet the heart that we are all used to seeing, so far it is a pair of contracting channels called heart tubes.
Ultrasound: 6th week of pregnancy
An ultrasound this week of pregnancy will show an embryo that has already grown and is now the same size as a pea. At the sixth week, its size is measured with an uzist, from the crown of the head to the coccyx. By this size, you can put the most accurate gestational age and determine the most likely date of birth. The size of the uterus is slightly increased. The presence of pregnancy at this time can also be established during an external ultrasound - that is, through the abdomen.
Ultrasound: 7th week of pregnancy
The embryo became 10,000 times larger than its size at the time of conception. The heart continues its active development. The ultrasound machine records the heart rate, normally up to 160 beats. You can see how the limbs of the future baby are actively formed. Now the formation of the tongue and mouth is taking place. The embryo has kidneys that excrete urine. They are made up of three parts.
Ultrasound: 8th week of pregnancy
The dimensions of the embryo are approximately 12-14 millimeters. The limbs become stronger and longer. Eyelids begin to form. Already formed ovaries and testicles are laid, depending on the sex of the unborn child. The movements of the embryo become more active.
Ultrasound: 9th week of pregnancy
Now the embryo does not have a tail and it bears the proud name - the fetus. An ultrasound this week measures the thickness of the placenta. The umbilical cord begins to be more clearly defined. Bone and cartilage tissue is formed. The ears are visualized. The limbs of the fetus are now acquiring more familiar outlines. However, the fingers of the fetus are still webbed.
Ultrasound: 10th week of pregnancy
The fruit continues its intensive development. On an ultrasound at nine weeks, it's about the size of a small plum. At this stage, the skeletal system is actively developing. On ultrasound, you can see how the future baby bends and unbends the arms at the elbows. In the gums are already formed teeth.
Ultrasound: 11th week of pregnancy
Ultrasound shows a fetus whose head is the same size as the torso. This is fine. This week, the fetus has become twice as large compared to the previous week. Now the fingers do not have membranes between them, and on a good device they can even be counted. The irises of the eyes are formed. Hair follicles begin to grow on the head of the fetus, marigolds begin to grow on the arms and legs, and ovaries develop in girls. Now the ears, nose, palate and tongue are fully formed.
Ultrasound: 12th week of pregnancy
The deadline for the most important ultrasound has come. At the twelfth week of pregnancy, ultrasound diagnostics is a mandatory examination. On examination, in addition to the size of the fetus, measurements are taken of the head, shoulder, ulna, femur, radius, tibia and fibula. The symmetry of the limbs and their motor activity, the presence of correctly located heart and stomach are assessed. During an ultrasound scan at this time, it is possible to diagnose possible heart defects with a high probability. Now the thickness of the collar zone is being measured. Normally, it is no more than 2.5 millimeters, a larger value suggests that the fetus has such a chromosomal abnormality as Down syndrome. The doctor carefully examines the nasal bones of the fetus. It is noted that in people suffering from Down syndrome, the nose is shorter, since the bones of the nose with this pathology complete their formation much later than in a fetus without pathologies. So the visualization of the bones of the nose on ultrasound at 1 week is a very important indicator.
Ultrasound: 13th week of pregnancy
At this time, the fruit is comparable to the size of a peach. It grows and all its internal organs are improved. Now there is an active formation of vocal cords. The gallbladder and liver of the fetus begin to produce bile, and the pancreas produces the most important hormone - insulin. Red blood cells are produced by the liver, spleen and bone marrow. The bone marrow also actively produces leukocytes - white blood cells that are responsible for the formation of the immune system of the unborn baby. On ultrasound at 13 weeks, the hair on the fetal head is already visible, but there is still no pigment in them and therefore they are white, almost colorless.
Ultrasound: 14th week of pregnancy
The fetus has grown to the size of my mother's fist. An ultrasound at 14 weeks of pregnancy shows that all the internal organs of the fetus have already taken their final position inside the abdominal cavity, and do not protrude in the form of an umbilical hernia, as it was a few weeks ago. Ultrasound already distinguishes even the pattern on the palms of the fetus. The face takes on a more defined shape. The length of the neck becomes longer. The fetus begins to actively suck its fingers - this is the formation of a natural reflex.
Ultrasound: 15th week of pregnancy
This week, the uterine muscle layer is being evaluated. Normally, it is thin and uniform.
The fetus is becoming more and more human-like: the ears and eyes are shifting to their natural places. The hair of the fetus begins to acquire pigment and very soon it will become clear what color they will be after birth. The baby begins to swallow amniotic fluid. This is fine. Thus, the baby is preparing for life outside the uterus.
Ultrasound: 16th week of pregnancy
At this time, ultrasound takes measurements of the placenta. Now its size is about 18 millimeters. The umbilical cord already fully ensures the delivery of nutrition and oxygen to the fetus. The baby starts to hiccup. At the 16th week of pregnancy, it is already possible to accurately determine the sex of the unborn baby.
Ultrasound: 17th week of pregnancy
It's time for the second mandatory ultrasound examination. Measurements are taken from the long bones of the fetus. At week 17, the device examines the fetal heart in order to finally exclude possible malformations in the development of this vital organ. They evaluate the main vessels that exit the heart, and also look at the structure of the kidneys.
Ultrasound: 18 weeks pregnant
This week, ultrasound determines the weight of the fetus. On average, an embryo at the eighteenth week of pregnancy weighs 230 grams. Weight is calculated based on fetometric parameters. Measurements are also made of the circumference of the abdomen, the head of the fetus, as well as the fronto-occipital region. The body of the fetus begins to produce meconium - waste products of its life.
Ultrasound: 19 weeks pregnant
In the gums of the fetus, permanent teeth begin to form. Ultrasound at this time clearly shows his jaw. This is important because their shape and size can tell a lot about the possible presence of chromosomal abnormalities. The fetus actively "works" with fingers, although they are still not fully developed.
Ultrasound: 20 weeks pregnant
The fruit already weighs 400 grams, and its length is about 20 centimeters. In boys at this time, the testicles begin to descend into the scrotum, and in girls a mass of the simplest eggs has formed. On ultrasound, you can already see how the baby yawns. He already has a daily routine like a newborn.
Ultrasound: 21 weeks pregnant
This week, all the same fetometric parameters are measured, as in the 20th week of pregnancy. The ultrasound shows that the legs of the fetus are stretched out. Due to this, the proportions of his body become more harmonious. Now all the internal structures of the fetus are being measured.
Ultrasound: 22 weeks pregnant
The main structures of the fetal brain are studied. IN without fail examine the cerebellum. The nervous system of the fetus has almost completed its formation. The integrity of the spinal cord and spine as a whole is studied. The future baby already perfectly distinguishes the times of day.
Ultrasound: 23 weeks pregnant
Ultrasound at this time measures the weight of the fetus, often it is at least half a kilogram! All fetal bones are measured. It can be seen that a layer of fat begins to form under the skin. If suddenly labor activity begins now, then it will no longer be a miscarriage, but a real birth and the baby can go out.
Ultrasound: 24 weeks pregnant
The placental structure is assessed. Normal placenta of homogeneous structure. Ultrasound looks at the arterial blood flow of the umbilical cord, and also evaluates the umbilical artery. Determine the degree of maturity of the placenta. The mass of the fetus is already more than 600 grams.
Ultrasound: 25 weeks pregnant
The most important thing to look at on ultrasound this week is amniotic fluid and its amount. Measurements are taken of all the bones of the child. The spine of the child is already fully formed. The baby's nostrils are now open, although a week ago they were tightly clogged. The baby reacts with active movements to voices familiar to him.
Ultrasound: 26 weeks pregnant
Ultrasound evaluates the structure of the fetal brain and its facial areas. The weight of the fetus is about 900 grams. The device records the opening of the child's eyes. However, he still sees imperfectly, is able to distinguish only light and darkness. The iris of his eyes is not yet pigmented.
Ultrasound: 27 weeks pregnant
This week of pregnancy, an ultrasound is done to assess the growth dynamics of the fetus and its weight gain. The symmetry of the limbs is assessed in order to exclude possible pathologies of the development and structure of the fetus.
Ultrasound: 28 weeks pregnant
The last, third trimester of pregnancy has begun. The fruit weighs more than a kilogram. An ultrasound evaluates its size, as well as its position inside the uterus. From this week, the baby begins to assume the position from which it is most likely to be born. However, even if the doctor said on the ultrasound that the child is lying incorrectly, then this is not a reason to worry - the uterus is still free enough to take the correct position.
Ultrasound: 29 weeks pregnant
The examination establishes the body weight of the child. It is believed that at this time he weighs half as much as he will weigh after birth. The bone marrow actively produces red blood cells. All the bones of the child are already fully formed.
Ultrasound: 30 weeks pregnant
The baby's diaphragm contracts in preparation for life outside the mother's belly. The pregnant woman feels these contractions. An ultrasound at this time evaluates the amount of amniotic fluid, as well as the size and weight of the baby, which, by the way, can already weigh one and a half kilograms.
Ultrasound: 31 weeks pregnant
This week, an ultrasound should be done in order to make sure that the child is developing at a normal pace. Fetometry of the bones and structures of the fetus is performed. Now is the time to appreciate the state of kidney development.
Ultrasound: 32 weeks pregnant
The blood flow in the umbilical arteries is assessed. In case of detection of deviations from normal indicators, dopplerometry will be carried out on the same pregnant woman - an assessment of all the arteries of the uterus, the arteries of the brain of the child and his aorta.
Ultrasound: 33 weeks pregnant
At this time, ultrasound shows the degree of maturity of the child's lungs. In practice, the baby's lungs are ready for life outside the mother's body, but in fact it will be better if he grows up a little more in the uterine cavity. The liver begins to accumulate personal iron (hemoglobin), which will be so necessary for the child after birth.
Ultrasound: 34 weeks pregnant
Evaluation of the growth and development of the child continues. The ultrasound shows that the baby has become even bigger and stronger. Bones continue to actively accumulate calcium, due to which they become stronger.
Ultrasound: 35 weeks pregnant
Despite the fact that the child, in principle, may well be born safely, his brain is still actively developing. On ultrasound, special inclusions in the bones of the child become noticeable - the so-called ossification nuclei. At this time, most often the child takes its final position.
Ultrasound: 36 weeks pregnant
On ultrasound, a specialist evaluates the position and size of the baby's head. It is most likely that the head is located in the lower part of the uterus. Fat continues to accumulate under the skin.
Ultrasound: 37 weeks pregnant
The amount of amniotic fluid in the uterine cavity is measured. Also, with the help of ultrasound, the functioning of all the internal organs of the child is assessed. The child is actively gaining weight.
Ultrasound: 38 weeks pregnant
Now the fetus is considered full-term. With the beginning of this week, you can no longer be afraid for the life of the baby. The purpose of ultrasound at this stage of pregnancy is to assess the degree of maturity of the placenta. The circumference of the head and the circumference of the chest of the child are also measured. Normally, they should be the same in diameter.
Ultrasound: 39 weeks pregnant
Ultrasound evaluates the umbilical cord, its length is measured, attention is paid to whether the child has an entanglement of it. Once again, placental maturity is assessed.
Ultrasound: 40 weeks pregnant
This is the last week of pregnancy, but there are women who give birth a little later than this period. Here they have this ultrasound, which evaluates the amniotic fluid and its quantity, the location of the umbilical cord, and also measures the weight of the child. According to statistics, more than 40% of women give birth before this time.
Ultrasound at 41 and 42 weeks of pregnancy evaluates the same indicators as at 40.
Of course, every expectant mother wants to know exactly how her future baby is developing. However, in the normal course of pregnancy, it is enough to undergo 2 mandatory ultrasounds in the first and second trimesters, possibly even at the very beginning, to confirm pregnancy in the uterine cavity.
Back in 1965, Swedish photographer Lennart Nilsson for the first time photographed the stages of embryo development using a powerful macro lens. And since then, as it turned out, nothing new has been invented yet. Nilsson's photographs are brilliant - he placed a microscopic macro lens of a camera and an illuminator on the tip of a cystoscope tube (a device that is used to examine the bladder) and shot a unique "report" 40 weeks long about how new life is born and develops.
Lennart Nilsson was born in 1922 on August 24 and is still alive, which is good news. In 2006, he released his latest book, Life. It will still be interesting to understand his books and photographs, but this will be ahead.
And now let's look at the stages of fetal development by week. After all, pregnant women always want to know how the life that is born in them develops. What the future little man sees, hears, feels.
It's been 7-8 hours...
The spermatozoon practically digs into the egg.
Up to eight weeks, the fetus is called an embryo.
1 Week
For the birth of a new life in the female body, ovulation occurs. At the same time, the temperature rises, the amount of vaginal mucus increases, and there may be slight pain in the ovarian region. Hormones are active in the body that cause a desire for intimacy. The egg is fertilized by the sperm.
2 weeks
The fertilized egg divides. The child inherits half of the parent's chromosomes. The sex of the unborn child depends on the sperm that fertilized the cell. The embryo then travels through the fallopian tube to the uterus. At the end of the second week, it attaches to the uterine mucosa. This insertion sometimes causes minor bleeding.
3 week
On the 18th day, the heart begins to pulsate in the fetus. The embryo separates from the membranes, actively developing. The nervous, skeletal, and muscular systems are born.
4 week
Often it is during this period that a woman learns about her own. Appear, there is no menstruation.
5 week
The length of the embryo is 6-9 mm. The brain and spinal cord develop, and the central nervous system is formed. Heart, head, arms, legs, tail, gill slit appear. You can see the face with holes for future eyes, mouth, nostrils.
A pregnant woman should consume enough folic acid to prevent neural tube defects in the baby. By the end of this week, the heart begins to beat.
6 week
The placenta is formed, which is for the fetus its lungs, liver, stomach, kidneys. The placenta is also called a child's place.
7 week
The expectant mother has significantly increased breasts. The length of the fetus reaches 12 mm, weight - 1 g. The fetus already has a vestibular apparatus, the rudiments of the abdomen, chest, eyes. The brain develops, fingers on the handles. The fetus begins to move.
8 week
The length of the embryo reaches 20 mm. The body of the fetus is formed. Face, nose, auricles, mouth differ. The skeleton continues to grow, the nervous system improves.
Skin sensitivity appears in the area of the mouth, face, palms. The gill slits die off, the rudiments of the genital organs appear.
9 week
All fetal muscles develop. On the hands and feet, the fingers already have nails. Sensitivity has the whole body of the baby. He touches his body, the umbilical cord, the walls of the fetal bladder. Thus, the tactile sensations of the fetus develop.
10 week
This is one of the most important stages in a baby's development. The nervous system and almost all organs develop. His eyelids are half open and will fully form over the next few days.
It is very important during this period of the mother not to drink alcohol and other toxic substances. The placenta does not yet fully protect the baby, so you can cause significant harm to his health.
11 week
The amount of blood in the body increases. Hormones produced during this period affect the thermoregulation of the body. Therefore, a woman increasingly feels changes in blood pressure, dizziness, weakness, stuffiness.
The fetus has eyelids, arms, legs. He is already making swallowing movements.
12 week
There are already red blood cells in the baby’s blood, the production of white blood cells begins, which will be responsible for protecting the body. In the meantime, antibodies protect the baby from infection. They come from the mother through the blood and are passive immunity.
13 week
The expectant mother is already proudly wearing her protruding tummy. The fetus is actively developing the skeleton and growth. This causes an increased intake of calcium. Therefore, a pregnant woman should take special preparations to replenish this trace element.
The baby begins to hear, thanks to special vibration receptors that are on the skin. The fetal vocal cords begin to form. The pancreas of the baby begins to produce insulin, the liver - bile. Villi are formed in the intestines, which are of great importance for digestion.
14 week
The fetus has training movements that are very important for the development of the lungs - inhalations and exhalations. Kidneys, bladder, urethra begin to function. The excreted urine is excreted by the placenta. The body of the baby begins to cover with lanugo. This is a fluff that performs a thermoregulatory and protective function of the fetal body.
In girls, the ovaries move into the pelvis. In boys, the prostate gland is formed. Blood forms inside the baby's bones. Hair growth begins on the head.
15 week
The hematopoietic system of the baby is actively developing. Veins and arteries supply all organs and systems with blood. The fetal heart beats twice as fast as the mother's, while passing about 23 liters of blood per day. The first foci of hematopoiesis appear in the walls of the gallbladder. You can find out the blood type and Rh factor of the child.
16 week
There is a large motor activity of the baby. The child's eyes open. Still no subcutaneous fat layer. The skin of the baby is very thin, with blood vessels translucent through it. The fetal skeleton consists of a flexible rod and a network of blood vessels.
17 week
During this period, the fetus has a rapid eye movement. In this regard, scientists argue that the child can dream. They are associated with his motor activity during the day.
18 week
The length of the fetus reaches 14 cm. The baby blinks, opens his mouth, makes grasping movements. It moves a lot in the mother's belly. All parts of the body are clearly visible, the face, the skin of the body turns pink.
19 week
Mom feels the baby move. Later, the movement turns into jerks. The strength of the pushes is different. It depends on the mood, activity of the mother, on the time of day. On average, in half an hour, the baby makes 20-60 shocks. There is an active development of the brain of the baby. He starts sucking his thumb.
20 week
At this time, future mothers seriously think about childbirth. It is good to choose courses for expectant mothers.
21 weeks
The length of the fetus already reaches 20 centimeters. The kidneys work in the fetus, meconium is produced in the intestines - pseudo-feces.
22 week
The weight of the fetus increases, fat deposits accumulate.
23 week
The length of the fetus reaches 30 cm, and the weight is 650 g. The lungs are quite developed. In case of premature birth during this period, the baby will be able to survive in the intensive care unit.
24 week
You can hear the baby's heartbeat by putting your ear to the mother's belly. During this period, the placental circulation of the child is of primary importance. The dimensions of the pelvis and lower limbs of the child are relatively smaller than the upper part. This is due to the fact that the upper body is better supplied with lower arterial blood. At the same time, the lungs receive very little blood.
25 week
Still soft cartilage of the nose and ears. The skin of the fetus is wrinkled, covered with lubrication, vellus hair is formed on it. The child is already falling asleep and waking up.
26 week
The baby has a well-developed sucking reflex. He often sucks his thumb. Such an occupation calms him, strengthens the muscles of the jaws and cheeks. Depending on which finger of which hand the child sucks, one can assume that he will be right-handed or left-handed.
The kid pushes, studies the space that surrounds him. At this time, the normal number of pushes of the child is 10 times in an hour.
The mother's uterus quadrupled in size. It bursts the lower ribs, resting against the hypochondrium.
27 week
The length of the fetus reaches 350 mm, weight -900-1200 g. The child's eyes open slightly, perceive the light. The mouth and lips become even more sensitive.
The boys' testicles have not yet descended into the scrotum. In girls, the small labia are not yet covered by the large ones.
28 week
On the head, the hair becomes thicker. Although some children are born almost bald. All of these are variations of the norm. Lanugo is practically disappearing. Although in some places on the body there may still be fluff, which will disappear in the first weeks after birth.
29 week
The baby has eyelashes. His eyelids are already closing and opening. Toenails grow.
30 week
The child reacts to the sounds of the external environment, may cry. The central nervous system controls body temperature and breathing rhythm. The lungs can now breathe normal air.
31 weeks
While awake, the child opens his eyes. Close them while sleeping.
32 week
The length of the fetus reaches 450 mm, its weight is about 2500 g. From this period, the baby is actively growing and gaining weight. His skin becomes thicker, pinkish, smooth.
33 week
During this period, the mass of the brain, the depth and number of gyri increase significantly. The most important functions of the fetal life are controlled by the spinal cord, parts of the central nervous system. After birth, the functions of the cerebral cortex will develop.
34 week
The child can raise and turn his head, due to the increase in muscle tone. Actively reacts to light, can squint from the direct rays of the sun.
35 week
Baby's lungs are fully developed. The fetus quickly develops a grasping reflex.
36 week
You may have the first harbingers of future birth. There is a "lowering" of the abdomen, when the height of the standing of the bottom of the uterus decreases. Mucus plug may come out of the cervix. During this period, frequent urination and defecation are characteristic. Not only that, the uterus presses on the intestines and bladder. Also, prostaglandins (hormones produced at that time) periodically cause a desire to empty.
The child pushes and moves less. The cervix shortens and becomes softer. Sometimes the external os of the uterus can open up to 1-2 cm.
37 week
The length of the child reaches 47 cm, weight - 2600 g.
38 week
The fetus is already quite viable, ready to be born. There may be hairs up to three cm on the head. Its skin is pale pink, has a layer of subcutaneous fatty tissue. The child performs about 70 reflex movements.
39 week
The baby is very sensitive to all the movements and condition of the mother. He responds with his movements to her anxiety, joy, fear.
40 week
The length of the child reaches 480-520 mm, weight - from 3200 to 3600 g. In girls, the small labia are covered with large ones. The boys' testicles descended into the scrotum. The cartilages of the nose and ears are elastic, nails are on the fingers. The baby is ready for birth.
In the first weeks after the birth of a baby, it is very important to stroke his little body, gently hug him. The child cannot yet touch himself and misses touching very much.
The memory of the baby very well preserves the sound and rhythm of the mother's heart. To calm the baby, sometimes it is enough to attach it to the left side of the mother's body.
- and here is Lennart Nilsson's book “A Child Is Born! The miracle of the birth of a new life.
Lennart Nilsson also shot short video stories about the development of the embryo, I found them when I studied information from his official website.
A selection of books about pregnancy and childbirth:
- Mommy is me, or the Diary of a pregnant woman about the most intimate. L. Lomanskaya
The Big Book of Pregnancy. McCarthy Jenny
Read this article:
The birth of a new life is the most beautiful mystery of nature. What could be more mysterious than the development of a child in the womb? The formation of a little man from a fertilized egg goes through a rather complicated path. Expectant mothers will be very interested to know how the intrauterine development of the child takes place by week.
The initial development of pregnancy
Pregnancy lasts 40 weeks or 10 obstetric months. The term "obstetric month" means 28 calendar days. But the beginning of pregnancy itself is considered the first day of the menstrual cycle. Thus, according to medical calculations, pregnancy lasts not 40, but 38 weeks.
So, fertilization occurred: the sperm entered the egg and formed a single cell with two nuclei. These nuclei, moving towards each other, form a zygote. A zygote is a single-celled embryo. This fact is the beginning of the development of a new life.
The zygote lives for 30 hours, after which its first division occurs. In the following days, cell division is repeated. On the fourth day of life, the embryo consists of 8-12 cells. By this time, this small lump reaches the uterine cavity, where the process of cell division increases intensively.
By the seventh day, the embryo already consists of hundreds of cells. On the eighth day, the embryo is attached to the wall of the uterus, where its walls have acquired a loose and thickened structure. The implantation process takes about 40 hours.
On the 14th day of the embryo's life, its back part thickens, preparing for the formation of the main organs.
Already in the second week after fertilization, pregnancy can be determined using tests. A small embryo already on the 3rd day of its life begins to produce a hormone - gonadoprin. All pregnancy tests are sensitive to this hormone.
At the end of 4 weeks, a woman discovers the absence of menstruation. The first symptoms of pregnancy will appear: nausea, dizziness, drowsiness.
During this period, the embryo is already commonly called an embryo, the size of which is about 1 mm.
The development of a child in the womb can be divided into three main periods:
- Blastogenesis - the first 15 days.
- Organogenesis is the development of the embryo from 15 days to 10 weeks of gestation.
- The fetal period is the development of the fetus in the womb.
If we divide the entire pregnancy into 3 equal periods, we get the following time periods: the first, second and third trimesters. Each trimester lasts 3 months.
If a woman is not yet aware of her “interesting position” and continues to lead an inappropriate lifestyle, then the embryo will most likely die at the stage of blastogenesis. If the mother's destructive lifestyle does not change during the first 12 weeks, there is a high probability of miscarriage.
Embryonic development of a child in the womb
The development of the embryo is a key moment of pregnancy, since during this period all vital organs are laid, which will affect the health of the baby in the future.
In no case should mom be nervous: only peace and positive emotions!
By the end of week 5, the embryo consists of three cell layers: ectoderm, endoderm and mesoderm. Ectoderm is the basis of the nervous system, hair and skin. The endoderm will develop into the gastrointestinal tract in the future. The mesoderm will turn into skeletal and muscle tissue, and will also form the basis of the circulatory, excretory and reproductive systems.
At week 5, a kind of heart tube is formed. We can assume that from this moment on, the “heart” begins to beat in the embryo. 
A groove forms on the back of the embryo, which is the basis of the spinal cord and the entire nervous system. It is very important for the expectant mother to take enough folic acid during this period. This substance contributes to the full formation of the nervous system of the unborn child.
At 6 weeks, the embryo takes on a C-shape. During this period, the laying of the primary intestine, cartilage of the skeleton, liver, kidneys, and thyroid gland occurs. The small embryo reaches 4 mm.
At the 7th week of pregnancy, toxicosis appears in women. This period is characterized by intensive development of the brain. The mouth and eye sockets begin to form. The respiratory system is actively developing, the heart begins to divide into chambers and arteries, the spleen and gallbladder are formed.
At week 8, with the help of ultrasound, the first movements of the embryo can be recorded.
At week 9, the fingers on the upper and lower extremities are determined, although they are still webbed. This period is characterized by the fact that the placenta begins to supply the embryo with nutrients and take away waste products. The fetus already has taste sensations.
At week 10, the membranes between the fingers disappear, the tail disappears. The sex of the child is still difficult to determine at this age, but the production of testosterone is already beginning in boys.
By week 11, the embryo weighs 5 g with a size of 3 cm. This is the final stage of embryonic development, subsequently the embryo will be called a fetus.
Intrauterine development of the child by weeks in the second trimester of pregnancy
At 12 weeks, almost all organs have formed in the fetus and the child begins to actively move inside the uterus.
This is the beginning of the third period of fetal development. At this time, as a rule, ultrasound is performed, which determines the quality of the child's development, genetic abnormalities.
If intrauterine abnormalities are found in the fetus, then the woman is recommended to undergo additional studies. But the final conclusions about chromosomal disorders can be made at 20 weeks with a control ultrasound. If serious pathologies are confirmed, doctors recommend terminating the pregnancy.
It is also worth noting that the older the parents, the higher the risk of developing pathologies in the child. However, in this case, it can be the other way around: the percentage of talented children born is higher just for older parents.
At week 13, the external genitalia differentiate. However, they can be distinguished already at 14-15 weeks with the help of ultrasound. At this stage, the formation of the intestine occurs. The baby is fed through the umbilical cord.
From the 14th week, the baby's skeleton begins to form, which was previously represented by cartilage. The length of the arms corresponds to the proportion of the body, and the legs are formed with some delay. The baby can yawn and suck his thumb. He perceives the vibrations of sounds, distinguishes well the mother's timbre of voice, music.
That is why it is important for expectant mothers to listen to beautiful classical music, thus instilling good taste in the baby.
At week 15, the blood vessels of the fetus become visible, which are enlightened through thin skin. The skeleton and bone marrow continue to form.
At 16 weeks, a planned ultrasound is performed, on which you can notice the movement of the baby's eye. The legs have become proportional to the length of the body and small nails begin to grow.
At 17-18 weeks, the small body is covered with a primary fluff - lanugo. This is such an original lubricant that protects the skin from the aquatic environment. During this period, fingerprints are laid, which are genetically predetermined.
The weight of the crumbs is 200 g with a height of 14 cm.
At 19-20 weeks, fetal growth begins to slow down somewhat. At this stage, subcutaneous fat is deposited, which keeps the small body warm. The respiratory system is improving more and more, but it is not yet able to function independently.
Mid-pregnancy: intensive fetal development
Starting from the 20th week, the rudiments of teeth form in the baby. The baby's hair grows more actively on the head, but their pigment is formed a little later.
From 22 weeks, mothers begin to feel how the baby is pushing. His weight at this time is 450 g, and his height is 19-20 cm.
From 23 weeks, the baby begins to gain weight. The child begins to see, he even dreams. There is an active development of the brain.
The muscular system and internal organs continue to improve actively. The respiratory system is getting more and more developed. In the intestines of the baby, the first feces accumulate - meconium.
The baby's skin is red and wrinkled. The child actively reacts to the position of the mother's body and to external sounds. Taste buds have already formed on the tongue, thanks to which food addictions are formed in the child. It is important for mothers to understand this and try to avoid spicy and bitter foods, as the little baby prefers sweets more.
The beginning of the third and final trimester - 27 weeks. By this time, all the organs of the fetus have already formed, and in the future they will be improved, as well as the development of the brain.
At week 29, the baby's immune system is formed. The heart rate reaches 120-130 beats per minute. The baby may hiccup, as evidenced by light tremors to the mother.
A child born at this time can survive with certain care. He is 37 cm tall and weighs 1150 g.
Prenatal development of the child in the last stages of pregnancy
For women who are preparing to become mothers of a healthy baby, of course, it will be superfluous to talk about the right lifestyle. Alcohol, cigarettes, lack of regimen, sleep and rest are very detrimental to the health of the unborn child.
At 30-32 weeks, the fat subcutaneous layer of the baby becomes thicker. Some babies are already turning head down at this stage.
Convolutions appear on the surface of the small brain. Pupils can already detect bright light. When conducting an ultrasound at this time, you can notice how the baby closes its eyes from bright light. For this reason, it is important to avoid ultraviolet rays and give up a beach holiday.
From 33 weeks, the little man is already getting cramped in his mother's tummy. At this time, the fetus turns head down, preparing for childbirth.
If a premature birth occurs at this stage, then the baby has every chance of surviving. However, he will be considered premature and will need special care in the hospital.
The skin of the baby becomes pink and not so wrinkled, thanks to subcutaneous fat. It makes up 8% of the total body weight.
Thanks to the appearance of marigolds, the baby can scratch himself. Some newborns are born scratched.
From the 37th week there is an active improvement of the respiratory system. Babies born during this period can already scream. Vellus hair on the body thins out, and on the head it grows intensively. The child every day is gaining 30 grams of fat.
By this time, the stomach drops, and it becomes easier for the mother to breathe. This usually happens two weeks before delivery.
By this time, the baby is ready to see the light. He is very cramped inside his mother: his knees are tightly pressed to his chin.
At week 39, the body becomes clean: the fluff remains only on the shoulders. The intestinal system of the crumbs is filled with meconium and amniotic fluid.
At 40 weeks, prenatal development ends, and a new person is born! A newborn photo becomes almost the most important photo in the house. After all, what could be more exciting and beautiful than the birth of a small miracle!
The development of a child in the womb occurs gradually during all 9 months of pregnancy. But in the first trimester (up to 12 weeks) the formation of all organs and systems of the body takes place - this is the most important stage in the development of the embryo, and in the second and third trimesters the child grows rapidly, gains weight, prepares for life outside the mother's womb. Consider the main points of development by week. By the way, it is these weeks (regarding the first trimester) that are considered the most dangerous for the baby. Any negative impact can lead to the formation of pathology or miscarriage.
What are the approximate stages of development of a child in the womb by week?
So, let's start with the 5th week of gestation (this is approximately 1 Week delay in menstruation in a woman, we consider in accordance with obstetric terms). The size of the embryo is only 3 millimeters, and the neural tube, heart and lungs, and thyroid gland are already beginning to form in it.
6 week- the embryo appears the rudiments of arms and legs. On ultrasound, the 2 hemispheres of the brain are already clearly distinguished. The formation of the intestine begins. The length of the embryo reaches 7 millimeters.
7 week. The interdigital spaces are already visible. On ultrasound, depressions (the eyes of the embryo), the nasal fold and auditory eminence are visible - the future ears. The length of the embryo is 8 mm.
8 week. During these 7 days, the embryo grows very quickly, at the beginning of the week it is 15-20 millimeters in size, at the end of the week it is 2 times larger. The embryo begins to form facial features. Ears, nose, neck appear.
9 week. The fingers and toes are already clearly defined. There is an intensive development of the circulatory system.
10 week characterized by the development of a sucking reflex in the fetus.
TO week 12 the fetus has good sensitivity, this indicates the development of its central nervous system. Reactions are noted not only to touch, but also to respiratory ones. The skeletal system gradually becomes stronger. This is how the baby develops in the womb during the first trimester of pregnancy.
IN 13-14 weeks the genitals of boys reach such sizes that they become visible during ultrasound examination on a good apparatus to an experienced specialist.
16 week characterized by ossification of the skull and increased mobility of the child, although most expectant mothers still do not notice the movements. The muscular system is actively developing. The baby already weighs about 180 grams and has a height of 13-14 centimeters.
IN 20 weeks During pregnancy, the baby becomes more and more like the cute babies we see on the covers of magazines. The head in relation to the body becomes more proportional. True, the body is completely covered with vellus hair, which, for the most part, will disappear by the time of childbirth, and there is almost no fat layer, which makes the baby look thin. But this does not prevent the child from actively moving inside the mother, and she already notices this. The height of the child reaches 19 centimeters, and the weight is 300 grams.
IN 24 weeks pregnancy, the child has the same height in numbers, weight 600-700 grams. He is actively moving, his heart is beating, and his beats are already heard through an obstetric stethoscope, if the dense fatty layer on the mother's abdominal wall and the placenta located on the anterior wall of the uterus do not interfere. Babies born prematurely at this time, doctors can go out with modern equipment, highly qualified neonatologists and other favorable conditions.
IN 28 weeks pregnancy, the child can already distinguish sounds, with ultrasound, if you conduct an experiment, it will be seen what kind of music or intonation of the voice the baby likes and which does not. Contrary to popular belief, the sound source does not have to be located in the mother's abdomen, since he hears sounds through his mother's ears. And from the side of the abdominal wall, it is reliably protected by amniotic fluid, which "extinguish" almost all sounds. To understand how a baby hears while in the womb, try turning on some music and diving headlong into the bath.
IN 32 weeks the child is quite viable, is born with a weight of 1500-2000 kilograms. However, his respiratory system is not yet adapted to life outside the womb, and therefore he should be in an incubator, where a constant level of temperature and moisture is maintained. Many vital reflexes are missing.
IN 36 weeks the child is almost ready for birth, the fat layer on his body becomes larger. The skin becomes smoother, vellus hair falls out (at birth, they can remain in a very small amount on the back of the baby). The sucking reflex is present, which means that he will be able to suck on his mother's breast, which is very important both in terms of his health and the psychological contact between mother and child.
38-40 weeks- a healthy child is fully viable.
These are the main stages in the development of a child in the womb.
