A fetus (synonymous with an embryo) is an organism that develops inside the egg shells or in the mother's body. Embryonic, or embryonic, development in humans is understood as the early period of development of the body (up to 8 weeks), during which a body is formed from a fertilized egg that has the basic morphological characteristics of a person. After 8 weeks developing organism a person is called a fetus (see).
Embryonic development is divided into a number of periods.
1. The period of a one-cell embryo, or zygote, is short-term, occurring from the moment of fertilization until the beginning of egg fragmentation.
2. Crushing period. During this period, cells occur. The resulting cells are called blastomeres. First, a bunch of blastomeres is formed, resembling a raspberry in shape - a morula, then a spherical single-layer blastula; the wall of the blastula is the blastoderm, the cavity is the blastocele.
3. Gastrulation. A single-layer embryo turns into a two-layer one - a gastrula, consisting of an outer germ layer - ectoderm and an inner one - endoderm. In vertebrates, already during gastrulation, the third germ layer, the mesoderm, appears. During evolution in chordates, the process of gastrulation became more complicated with the emergence of an axial complex of primordia (the anlage of the nervous system, axial and musculature) on the dorsal side of the embryo.
4. The period of separation of the main rudiments of organs and tissues and their further development. Simultaneously with these processes, the unification of parts into a single developing whole is intensified. The ectoderm forms the skin, the nervous system, and partly from the endoderm the epithelium of the digestive canal and its glands; from mesoderm - muscles, epithelium of the genitourinary system and serous membranes, from mesenchyme - connective, cartilage and bone tissue, vascular system and blood.
When conditions change, the course of development of individual parts of the embryo may change and the germ layers may give rise to organs and tissues that should not develop from them under normal conditions. Factors that change the conditions of development can be the environment (its chemistry, temperature, etc.), interaction between parts (cells, rudiments) of the embryo itself, as well as heredity. All these factors are closely interconnected.
Rice. 1. Scheme of the early stages of development of the human embryo: a - stage of the inner cell mass; b - eight-day embryo; c - twelve-day embryo; d - thirteen, - fourteen day embryo. 1 - trophoblast; 2 - blastocele; 3 - amnion cavity; 4 - endoderm cells; 5 - amnion; 6 - embryo; 7 - yolk sac; 8 - mesoderm cells; 9 - stalk; 10 - chorionic villus; 11 - extraembryonic coelom.
Rice. 2. The embryo and its membranes are on early stages development (a - c - successive stages): 1 - chorion; 2 - allantois; 3 - yolk sac; 4- amnion; 5 - extraembryonic coelom; 6 - umbilical cord; 7 - umbilical vessels; 8 - amnion cavity.
Rice. 3. Human embryo: a - by the end of the 4th week; b - by the end of the 5th week; c - by the end of the 7th week after fertilization.
In humans, fertilization occurs in the oviduct. The crushing process takes place within 3-4 days, when the embryo moves along fallopian tube to the uterus. As a result of fragmentation, a shell is formed from the surface blastomeres, which participates in the nutrition of the embryo - the trophoblast. The central blastomeres form the embryoblast, from which the body of the embryo develops. For 4-6 days the embryo is in the uterine cavity. With the beginning of the second week, the embryo immerses into the wall of the uterus (implantation). In a 7.5-day-old embryo, an amniotic sac forms, the part of which facing the endoderm is the ectoderm of the embryo. During this period, the embryo has the shape of a shield (disc). From it, cells of extraembryonic mesenchyme migrate into the cavity of the blastocyst and fill it (Fig. 1). Together with the trophoblast, it forms the villous membrane of the embryo - the chorion (see). By the end of the second week, a yolk vesicle forms. As a result of mesenchyme overgrowing the amniotic and yolk sacs, the amnion and yolk sac are formed.
"Extraembryonic" parts play an important role in the development of the embryo. The yolk sac in the human embryo functions only in the early stages of development, participating in the nutrition of the embryo and performing a hematopoietic function. In oviparous higher vertebrates, the allantois acts as a urinary sac; in humans, it is a finger-like outgrowth of the hindgut, along which it grows to the chorion. The amnion - a water membrane - forms a closed sac around the embryo, filled with liquid - amniotic fluid. It protects the embryo from harmful influences and creates favorable conditions for its development (Fig. 2).
At the 3rd week of development, a dense cord of growing cells stands out on the dorsal side of the embryo - the primary streak, the head section of which thickens and forms the primary (Hensen's) node. The cells of the primitive streak are immersed in the primary groove, penetrate into the space between the ectoderm and endoderm and give rise to the middle germ layer. In the 3rd week, the dorsal chord and neural tube are formed.
At the 4th week, the embryo separates from the extra-embryonic parts and, as a result of increased growth, curls into a tube. At the same time, the mesoderm differentiates and body segments - somites - are formed (Fig. 3, a). In parallel with segmentation, the initial processes of organogenesis (see) and histogenesis occur. At the 5th week, the rudiments of the arms and then the legs appear, on the 6th they are divided into main sections, and on the 7th the rudiments of the fingers appear (Fig. 3, b and 3, c). At the age of 8 weeks, the embryo acquires the basic morphological characteristics of a human being. appearance and in the internal organization. Its length (from the crown to the coccyx) is 4 cm, weight is 4-5 g. By the end of the 8th week, the laying of the embryonic organs ends.
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The birth of a new life is the most beautiful secret of nature. What could be more mysterious than the development of a child in the womb? Formation little man From the fertilized egg there is a rather complex path. Expectant mothers will be very interested to know how the child’s intrauterine development occurs week by week.
Initial development of pregnancy
Pregnancy lasts 40 weeks or 10 obstetric months. The term “obstetric month” implies 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 penetrated the egg and formed a single cell with two nuclei. These nuclei, moving towards each other, form a zygote. A zygote is a one-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 subsequent 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 intensively increases.
By the seventh day, the embryo already consists of hundreds of cells. On the eighth day, the embryo attaches 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. Already on the 3rd day of its life, a small embryo begins to produce a hormone - gonadoprin. All pregnancy tests are sensitive to this hormone.
At the end of the 4th week, a woman notices the absence of menstruation. The first symptoms of pregnancy will appear: nausea, dizziness, drowsiness.
During this period, the embryo is already 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 pregnancy.
- 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: 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
Embryo development is a key moment of pregnancy, since during this period all vital organs are formed, which will affect the baby’s health in the future.
Mommy should never 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 in the future into the gastrointestinal tract. 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 forms. We can assume that from this moment the embryo’s “heart” begins to beat. 
A groove is formed 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 promotes the full formation of the nervous system of the unborn child.
At week 6, the embryo takes on a C-shape. During this period, the formation of the primary intestine, skeletal cartilage, liver, kidneys, and thyroid gland occurs. The small embryo reaches 4 mm.
At the 7th week of pregnancy, women experience toxicosis. This period is characterized by intensive development of the brain. The mouth and eye sockets begin to form. The respiratory system actively develops, the heart begins to divide into chambers and arteries, the spleen and gall bladder are formed.
At week 8, ultrasound can record the first movements of the embryo.
At week 9, the fingers on the upper and lower extremities are visible, 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 embryo already has taste sensations.
At week 10, the membranes between the toes disappear and the tail disappears. The gender of the child is still difficult to determine at this age, but boys are already beginning to produce testosterone.
By the 11th week, the embryo weighs 5 g and measures 3 cm. This is the final stage of embryonic development; the embryo will subsequently be called a fetus.
Intrauterine development of a child by week in the second trimester of pregnancy
At 12 weeks, almost all organs of the fetus have formed 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, an ultrasound is performed, which determines the quality of the child’s development and genetic abnormalities.
If intrauterine abnormalities are detected in the fetus, the woman is recommended to undergo additional tests. But final conclusions about chromosomal abnormalities 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, the opposite may be true: the percentage of talented children born is higher among older parents.
At week 13, the external genitalia differentiate. However, they can be distinguished already at 14-15 weeks using ultrasound. At this stage, the formation of the intestines occurs. The baby receives nutrition 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 proportions 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 timbre of his mother’s voice and music.
That is why it is important for expectant mothers to listen to beautiful classical music, thus instilling in the baby good taste.
At week 15, the blood vessels of the fetus become visible, which become visible through the thin skin. The skeleton and bone marrow continue to form.
At 16 weeks, a routine ultrasound is performed, where you can notice the movement of the baby’s eyes. 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 primary fluff - lanugo. This is a natural lubricant that protects the skin from the aquatic environment. During this period, fingerprints are laid, which are genetically predetermined.
The baby weighs 200 g and is 14 cm tall.
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 baby's teeth begin to form. The baby's hairs on his head grow more actively, but their pigment is formed a little later.
From the 22nd week, mothers begin to feel the baby pushing. His weight at this stage 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. The brain is actively developing.
The muscular system and internal organs continue to actively improve. The respiratory system is becoming increasingly developed. The first feces - meconium - accumulate in the baby's intestines.
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 the child develops food preferences. It is important for mothers to understand this and try to avoid spicy and bitter foods, since the little one prefers sweets.
The beginning of the third and final trimester is week 27. 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 it is formed the immune system baby. The heart rate reaches 120-130 beats per minute. The baby may hiccup, as evidenced by slight tremors to the mother.
A child born at this stage can survive with certain care. His height is 37 cm and weight is 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, it will, of course, be superfluous to talk about the right lifestyle. Alcohol, cigarettes, lack of routine, sleep and rest have a very detrimental effect on the health of the unborn child.
At 30-32 weeks, the baby’s subcutaneous fat layer becomes thicker. Some babies are already turning head down at this stage.
Convolutions appear on the surface of the small brain. The pupils can already detect bright light. When performing an ultrasound at this stage, 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 the 33rd week, the little man already becomes cramped in his mother’s tummy. At this stage, the fetus turns head down, preparing for birth.
If premature birth occurs at this stage, the baby has every chance of survival. However, he will be considered premature and will require special care in the hospital.
The baby's skin 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. The vellus hair on the body thins, and on the head it grows rapidly. The child gains 30 grams of fat every day.
By this time, the stomach drops, and it becomes easier for mom to breathe. This usually happens two weeks before birth.
By this time the baby is ready to see the light. He is very cramped inside his mother: his knees are pressed tightly to his chin.
At week 39, the body becomes clean: the fluff remains only on the shoulders. The baby's intestinal system is filled with meconium and amniotic fluid.
At 40 weeks, prenatal development ends and the baby is born. new person! Photos of newborns become almost the most important photo in the house. After all, what could be more exciting and beautiful than the birth of a small miracle!
Expectant mothers are always curious about how the fetus is developing during a time when it is so eagerly awaited. Let's talk and look at photos and pictures to see how the fetus grows and develops week by week.
What does the belly do for 9 months in mom’s tummy? What does he feel, see and hear?
Pregnancy: fetal development by week
Let's start the story about the development of the fetus week by week from the very beginning - from the moment of fertilization. A fetus up to 8 weeks old is called embryo, this occurs before the formation of all organ systems.
Embryo development: 1st week
The egg is fertilized and begins to actively fragment. The egg travels to the uterus, freeing itself from the membrane along the way.
On days 6-8 it is carried out implantation eggs - implantation into the uterus. The egg settles on the surface of the uterine mucosa and, using chorionic villi, attaches to the uterine mucosa.
Embryo development: 2–3 weeks
Picture of embryo development at 3 weeks.
The embryo is actively developing, beginning to separate from the membranes. At this stage, the rudiments of the muscular, skeletal and nervous systems are formed. Therefore, this period of pregnancy is considered important.
Embryo development: 4–7 weeks
Fetal development by week in pictures: week 4
week 4
Photo of an embryo up to the 6th week of pregnancy.
The embryo develops a heart, head, arms, legs and tail. The gill slit is identified. The length of the embryo in the fifth week reaches 6 mm.
Fetal development by week photo: week 5
At the 7th week, the rudiments of the eyes, stomach and chest are determined, and fingers appear on the arms. The baby has already developed a sense organ - the vestibular apparatus. The length of the embryo is up to 12 mm.
Fetal development: 8th week
Fetal development by week photo: week 7-8
The face of the fetus is determined; a mouth, nose, and ears can be distinguished. The head of the embryo is large and its length correlates with the length of the body; the fetal body is formed. All the significant, but not yet fully formed, elements of the baby’s body already exist. The nervous system, muscles, and skeleton continue to improve.
The development of the fetus in the photo already has sensitive arms and legs: week 8
The fetus developed skin sensitivity in the mouth area (preparation for the sucking reflex), and later in the area of the face and palms.
At this stage of pregnancy, the genitals are already visible. The gill slits die off. The fruit reaches 20 mm in length.
Fetal development: 9–10 weeks
Fetal development by week photo: week 9
Fingers and toes already have marigolds. The fetus begins to move in the pregnant woman's belly, but the mother does not feel it yet. A special stethoscope can be used to hear the baby's heartbeat. The muscles continue to develop.
Fetal development by week photo: week 10
The entire surface of the fetal body is sensitive and the baby enjoys developing tactile sensations by touching his own body, the walls of the amniotic sac and the umbilical cord. This is very interesting to observe on ultrasound. By the way, the baby first moves away from the ultrasound sensor (of course, it’s cold and unusual!), and then puts his hands and heels to try to touch the sensor.
It’s amazing when the mother puts her hand to her stomach, the baby tries to master the world and tries to touch with his hand “from the other side.”
Fetal development: 11–14 weeks
Fetal development in the photo of the leg: week 11
The baby's arms, legs and eyelids are formed, and the genitals become visible (you can find out the gender of the baby). The fetus begins to swallow, and if it doesn’t like something, for example, if something bitter gets into the amniotic fluid (the mother ate something), then the baby will wince and stick out its tongue, making fewer swallowing movements.
The skin of the fruit appears transparent.
Fetal development: week 12
Photo of a 12 week fetus on 3d ultrasound
Fetal development by week photo: week 14
The kidneys are responsible for producing urine. Blood forms inside the bones. And hairs begin to grow on the head. It is moving more coordinated.
Fetal development: 15–18 weeks
Fetal development by week photo: week 15
The skin turns pink, the ears and other parts of the body, including the face, are already visible. Imagine, the child can already open his mouth and blink, as well as make grasping movements. The fetus begins to actively push in the mother's tummy. The sex of the fetus can be determined by ultrasound.
Fetal development: 19–23 weeks
Fetal development by week photo: week 19
The baby sucks his thumb and becomes more energetic. Pseudo-feces are formed in the fetal intestine - meconium, the kidneys begin to work. During this period, the brain develops very actively.
Fetal development by week photo: week 20
The auditory bones become ossified and are now able to conduct sounds, the baby hears the mother - heartbeat, breathing, voice. The fetus rapidly gains weight and fat deposits form. The weight of the fruit reaches 650 g, and the length is 300 mm.
The lungs at this stage of fetal development are so developed that the baby is artificial conditions intensive care unit can survive.
Fetal development: 24–27 weeks
The lungs continue to develop. Now the baby is already falling asleep and waking up. Vellus hairs appear on the skin, the skin becomes wrinkled and covered with grease. The cartilage of the ears and nose is still soft.
Fetal development by week photo: week 27
Lips and mouth become more sensitive. The eyes develop, open slightly and can perceive light and squint from direct sunlight. In girls, the labia majora do not yet cover the labia minora, and in boys, the testicles have not yet descended into the scrotum. The weight of the fruit reaches 900–1200 g, and its length is 350 mm.
9 out of 10 children born at this stage survive.
Fetal development: 28–32 weeks
Now the lungs are adapted to breathe normal air. Breathing is rhythmic and body temperature is controlled by the central nervous system. The baby may cry and respond to external sounds.
The child opens his eyes while awake and closes them while sleeping.
The skin becomes thicker, smoother and pinkish. Starting from this period, the fetus will actively gain weight and grow rapidly. Almost all babies born prematurely at this stage are viable. The weight of the fruit reaches 2500 g, and the length is 450 mm.
Fetal development: 33–37 weeks
Fetal development by week photo: week 36
The fruit reacts to the light source. Muscle tone increases and the baby can turn and raise his head. On which the hairs become silky. The child develops grasp reflex. The lungs are fully developed.
Fetal development: 38–42 weeks
The fetus is quite developed, prepared for birth and considered mature. The baby has honed more than 70 different reflex movements. Due to subcutaneous fatty tissue, the baby's skin is pale pink. The head is covered with hairs up to 3 cm.
Fetal development by week photo: week 40
The baby perfectly mastered his mother's movements, knows when she is calm, excited, upset and reacts to this with her movements. Fruit for intrauterine period gets used to moving in space, which is why babies love it so much when they are carried in their arms or rolled in a stroller. This is a completely natural state for a baby, so he will calm down and fall asleep when he is rocked.
The nails protrude beyond the tips of the fingers, the cartilages of the ears and nose are elastic. In boys, the testicles descend into the scrotum, and in girls, the labia majora cover the labia minora. The weight of the fruit reaches 3200-3600 g, and the length is 480-520 mm.
After birth, the baby yearns for touches on his body, because at first he cannot feel himself - the arms and legs do not obey the child as confidently as they did in amniotic fluid. Therefore, so that your baby does not feel lonely, it is advisable to carry him in your arms, hold him close to you, and stroke his body.
And further, the baby remembers the rhythm and sound of your heart very well. Therefore, you can comfort the baby this way - take him in your arms, put him on left side and your miracle will calm down, stop crying and fall asleep. And for you, the time of bliss will finally come.
AlvoGenium is 200 mg of one of the main components of Omega-3 - Docosahexaenoic acid (DHA). The drug is available in convenient, soft capsules and is suitable as a source of vitamins for pregnant and lactating women. Unique, plant-based DHA, free of possible ocean pollution. Promotes healthy brain development in the fetus, strengthens the health of the mother during pregnancy and compensates for the lack of vitamins during lactation. 1
DHA (OMEGA 3) - VITAMINS FOR BRAIN DEVELOPMENT
There are many types of Omega-3 fatty acids and vitamins based on them.
Which vitamins should you take?
For brain development and health, the answer is very simple: special attention should be paid to taking DHA and vitamins for pregnant and lactating mothers, which are produced on its basis. And this is AlvoGenius. Just what you and your baby need.
Omega-3 - vitamins for beauty and health
What is the source of DHA and polyunsaturated fatty acids that provide energy for full life? Of course it's Omega-3. This substance is not synthesized in the human body, and therefore everyone who cares about their health should eat foods rich in Omega-3.
This component is especially important for expectant mothers and nursing women, since during this difficult period they must provide useful substances not only to themselves, but also to their baby.
Vitamins for nursing mothers
All organs and systems of a newborn develop very quickly, for this they need complete “building material”. And it is contained in sufficient quantities in the Omega-3 complex. It’s too early for the baby to take vitamins, but if the mother takes useful material in the right quantity, then children's body will receive everything you need in full.
Omega-3 is essential for:
- Development of brain cell membranes;
- Strengthening the immune system;
- Development of memory and attention.
Do you want to see your children healthy and happy? Don't forget to take vitamins during lactation!
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2 Jensen, C. V. (2010). Effects of early maternal docosahexaenoic acid intake on neuropsychological status and visual acuity. The Journal of Pediatrics, 157, 900-905.
3 Smuts, C. H. (2003, March). A randomized trial of docosahexaenoic acid supplementation during the third trimester of pregnancy. Obstetrics & Gynecology, 101(3), 469-479.
4 Brenna, J. L. (2009). Background paper on fat and fatty acid requirements during pregnancy and lactation. Annals of Nutrition & Metabolism, 55, 97-122.
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6 Simopoulos, A. (2006). Evolutionary aspects of diet, the omega 6- omega3 ratio and genetic variation- nutritional implications for chronic diseases. Biomedicine & Pharmacotherapy, 60, 502-507.
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8 Hughes, T. B. (2005). New paradigms for supporting the resilience of marine ecosystems. Trends in ecology and evolution, 380-386.
9 Ramón, R. B. (2009). Fish consumption during pregnancy, prenatal mercury exposure, and anthropometric measures at birth in a prospective mother-infant cohort study in Spain. The American Journal of Clinical Nutrition, 90, 1047-1055.
10 Arterburn, L. H. (2006). Distribution, interconversion, and dose-response of n-3 fatty acids in humans. Am J Clin Nutr, 1467S-1476S
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Today we will discuss and show the intrauterine development of the fetus by week of pregnancy in photos and videos, we will analyze everything step by step and in great detail.
Pregnancy is a wonderful physiological process in the female body, which can be characterized by the development of an egg fertilized by a sperm into an embryo, and then a fetus.
How long does the average pregnancy last? healthy woman– approximately 9 calendar months or 10 obstetric months. The development of any pregnancy is easier to view and track by trimester.
But it is no less interesting to consider in more detail and with photos the intrauterine development of the fetus week by week.
Embryo or fetus?
In obstetric practice, two concepts are often encountered that refer to the stages of bearing an unborn child - “embryo” and “fetus”. How are they different and what is the difference between them?
Intrauterine development The fetus is divided into stages:
- Embryonic– which lasts for the first 8 weeks of pregnancy. Due to its small size and relatively different appearance from a fully formed human, the fetus in the womb is called an embryo.
- Fetal- lasts from the 9th week of pregnancy until the very moment of birth. The baby is already more formed and looks like a little man; it is called a fetus.
The genetic material that the father and mother put into the unborn child will directly influence the development of the embryo, and the first trimester of pregnancy and the condition of the mother will have a subsequent impact on the fetus.
baby development from embryo to fetus by week 1-10 weeks
1 Week
If we talk about the first week of pregnancy, we need to clarify what is taken as the main starting point. In gynecology, however, they often focus on obstetric timing.
The first few days after conception, even with multiple pregnancies, future mom doesn't feel any characteristic features. This is the time when the menstrual cycle should begin.
The hCG level is within the normal range (5 IU/ml for non-pregnant women). In the first week, pregnancy tests are unlikely to show the coveted 2 stripes. Since it is based on the level of hCG that pharmacy tests react.
2 week
The period is characterized by the maturation of the zygote in the uterus or fallopian tube. And if everything goes well, the pregnancy will take place.
After conception, the fertilized egg attaches to the wall of the uterus.
If attachment has passed, then there may be discharge indicating this event and the appearance of the embryo. They are similar in consistency to egg whites and can sometimes be bloody.
If the discharge at week 3 is similar in color and consistency to menstruation, then this is not normal and you should consult a doctor.
3 week
The third week is the starting point in a woman’s pregnancy; it is after it that we can say whether conception has occurred. The embryo is so small that its size does not exceed 0.15-0.2 mm in length and weighs 2-3 μg.
If the sperm does not fertilize the egg, your period may begin in a couple of days ahead of schedule. This will be easy to notice if you keep a calendar.
Heavy discharge in the third week can cause a miscarriage.
4 week
The embryo at 4 weeks of pregnancy is actively developing and a pregnant woman can feel changes in her body. Many people note severe swelling of the breasts, the nipples become bright and become especially sensitive. Menstruation does not occur, but sometimes some pregnant women may experience scanty discharge, which should not alarm her.
This time of fetal development is especially dangerous if there is excessive physical activity, lifting weights. There is also a risk of complications for the embryo when infectious diseases, which are most often accompanied by high temperature. Alcohol and cigarette abuse are also dangerous. It's better to exclude them completely.
So far, the level of hCG increases only in the blood. And on an ultrasound, you will most likely notice a yellow jelly-like body that provides nutrition to the embryo until the placenta begins to fully perform its protective functions. Progesterone, the pregnancy hormone, is actively produced.
The size of the embryo is about 2-3 mm in length.
5 week
During this stage of pregnancy, the size of the uterus changes. At the ultrasound examination stage, a qualified specialist can tell about the presence or absence of a multiple pregnancy.
Changes in the body of the expectant mother become noticeable and even more tangible. Many women notice a slight increase in temperature and weakness. But if your condition resembles cold-like symptoms, consult a doctor immediately.
week 6
At this stage, the pregnant woman begins to actively show signs of future motherhood. The uterus of a pregnant woman at 6 weeks is the size of a plum. If you contact a gynecologist, he will already be able to feel it.
If you are pregnant with twins, then an ultrasound at this stage will show the presence of two fetal sacs and a yolk sac. At the 6th week of pregnancy, an examination will show small tubercles on the embryo - this is the site of development of future limbs. You can already listen to the heartbeat of the embryo using a special device. The embryo is no more than 4-9 mm in length and weighs no more than 0.2 - 0.8 grams.
week 7
There are important changes happening this week. The embryo's heart becomes four-chambered, and the main large blood vessels are formed.
The first trimester can be characterized by the continued development of vital internal organs and other body systems of the embryo. It weighs about 1 g, and the size from the tailbone to the crown is no more than 13 mm.
The unborn child, although slowly, begins to straighten up. His brain begins to develop very rapidly.
The baby's face is being improved and the upper limbs are being developed. The umbilical cord of the embryo completes its formation and a mucous plug is formed.
8 week
The fruit begins to move and increase significantly. Its length is 14-20 mm. Every day the baby’s face acquires more and more familiar human features.
The formation of the main vital organs and systems is gradually being completed. And some are already actively functioning. The embryo gradually develops an optic nerve, and the appearance of the rudiments of future genital organs can also be observed.
Week 9
The embryo reaches a length of no more than 22-30 mm, and its weight is still so small, about 2 g. At this stage, the cerebellum and pituitary gland are actively forming, the middle layer of the adrenal glands is formed, lymph nodes are born, as well as future genital organs.
The formed limbs begin to slowly move, learn to bend, and the first muscle fibers appear. The fetus develops the ability to subsequently urinate.
10 week
The embryo weighs about 5 g and its length is approximately 30-40 mm. The heart of a nascent man beats at a speed of 150 beats per minute. The baby’s limbs are formed, and sometimes you can already see your fingers in ultrasound images. In the baby, most of the gastrointestinal tract organs have already formed.
At week 10, the foundation is laid for the formation of subsequent baby teeth. This obliges the expectant mother to keep her food calendar and also mark each consumption of a dairy product in it.
11-20 weeks
11 week
At week 11, the fetus weighs about 8 g, and its “height” is approximately 5 cm. From this moment, the former embryo gradually grows and enters the fetal stage.
His little heart is already functioning fully, the vessels and circulatory system are completing their formation. The placenta around the fetus becomes very strong and dense. A baby's liver takes up about 10% of his body. The intestines are already trying to make the first movements reminiscent of peristalsis.
genitals are formed. The color of the fetus's eyes is determined and the sense of smell already appears. The baby's fingers and palms become sensitive.
12 week
The most important stage in fetal development. Critical moments largely depend on the lifestyle of the expectant mother and her health and eating behavior. The baby's body is no more than 6-9 cm in length.
But at the same time, the unborn baby already has all the fingers and toes, and the organs of the gastrointestinal tract are actively forming. The immune system improves and begins to function.
Week 13
The critical cycle is ending and things will become easier for the expectant mother. Her baby's future baby teeth are embedded. All systems are developing and continue to improve. Muscle and bone tissue are slowly growing.
The genital organs are already differentiated. The length of the fetus at week 13 reaches 8 cm, and the weight is still very small - 15-25 g.
Week 14
At this wonderful stage, it is already possible to determine the sex of the child. The baby is actively developing and has already grown from about 8 to 10 cm, and weighs about 30-40 g. Every day the fruit looks more and more like a little man.
The bones of the fetus become stronger, the skeleton gradually grows, and ribs are already beginning to form. The movements of the baby's diaphragm are increasingly reminiscent of breathing. The baby already has a Rh factor and a blood type, as its composition is gradually stabilizing.
Week 15
At this stage, the fetus begins to form the cerebral cortex. This is a long process that will take most of the entire second trimester. The endocrine system of the small organism comes into operation. The sebaceous and sweat glands begin their activity.
At week 15, the fetus has already formed taste buds, but the respiratory system is still improving.
The baby weighs about 70 g and is about 10 cm tall. At this stage, even if you have a multiple pregnancy, their size does not interfere with free movements for you or the babies.
Week 16
During this period, the baby is no more than 11 cm tall, and weighs approximately 120 g. The baby’s neck has already taken a stable, even position, the head rotates freely.
The ears and eyes are still in an unusual place, but are gradually starting to rise up. The baby's liver begins to take over its functions.
In case of multiple pregnancy, the expectant mother can feel the movements of the children, who are becoming more and more active.
Week 17
The baby’s immune system begins to actively work, and interferon and immunoglobulin begin to be produced. The baby himself is already able to provide protection against various infections coming from outside. But still, microbes can be critical for such a fragile organism.
At week 17, the baby develops, although not large, a layer of fat. The girl has a uterus. The length of the fruit is no more than 13 cm and weighs about 140 grams.
The baby is already able to catch sounds and feel emotions. Therefore, be sure to establish contact with the baby. Talk to him, stroke his belly, sing songs. This is extremely important for establishing a bond between the expectant mother and the baby.
18 week
At this stage, the immune system and brain are actively developing, and adipose tissue continues to accumulate. In the fetus, you can notice the formation of the rudiments of molar teeth. Height is approximately 14 cm, weight - 200 grams, like a stick of butter.
The baby has a clear reaction to light, and hearing is noticeably enhanced.
Week 19
At this stage, there is a sharp and significant jump in the formation of the fetus and its development. His movements can be called more meaningful and orderly. The respiratory organs are improving and developing. The tiny baby's body is covered with the so-called vernix lubrication.
The baby's head begins to rotate freely, and he can hold it in a fixed position. The fetus weighs about 250 g at week 19, and its height does not exceed 15 centimeters.
Week 20
The fetal heartbeat can already be heard with an ordinary stethoscope. The baby's limbs are fully formed and visible on ultrasound. For the baby, sounds become more audible. The length of the fruit is approximately 25 cm, and the weight is about 300 grams. Movements are already felt in the tummy.
21-30 weeks
21 weeks
The height of the fetus at this stage does not exceed 26 cm, and its weight is 360 grams. Digestive system The tiny man is working much more actively than before. He often swallows amniotic fluid. Muscle and bone tissue gradually grows and strengthens. The spleen is connected to organs that work independently.
Week 22
This week the baby weighs about 400 grams. Height can reach up to 28 cm. The fetus is already quite viable, even if it is born prematurely.
His brain and spinal skeleton are already fully formed. Reflexes continue to develop. The baby's heart increases significantly in size.
23 week
By this period, the fetus is already quite well formed, its digestive organs work independently. So far, slowly, but fatty tissue is accumulating. The genitals can be easily distinguished.
The baby's height can reach 28 cm, and weight - 500 g. The spleen becomes more active.
Week 24
Outwardly, your fetus is already quite similar to a newborn baby. Due to lack large quantities fat layer, the baby weighs only about 400 - 600 g with a height of 23-30 cm. But from the 24th week, your fetus will begin to independently produce growth hormone, which will allow you to gain weight faster.
The respiratory organs are entering their final stage of development. Reflexes develop very quickly, all senses improve. The baby is already developing a sleep-wake pattern. He begins to sense and respond to his mother's emotions. Fetal movements become more sensitive for the expectant mother.
Week 25
Your fetus this week weighs about 700 g, and the tiny man is approximately 34 cm tall. Every day he becomes more and more like a newborn.
Your baby's lungs are preparing to take their first breath.
The sense of smell at this stage is very well developed, and the baby also senses even minor mood swings of the mother and can react to them. The bone skeleton develops and begins to become more and more actively overgrown with muscles. Boys develop testicles, and girls develop a vagina.
Week 26
An unusually wonderful week of pregnancy. Your baby, being in your tummy, already acquires its own individual characteristics and is even able to recognize the voices of its parents. Therefore, try to talk to your baby more often and read to him.
The eyes gradually open. The baby's skeleton is noticeably strengthened. His lungs are not yet fully formed, but are already taking on their final shape.
The baby's brain begins to produce various hormones. Weight is approximately 750 g, but height reaches approximately 36 cm. During this period, the baby sleeps a lot, 16-20 hours. His movements can be noticed.
Week 27
The baby weighs about 900 g. Every week there is active growth and build-up of muscle mass and subcutaneous fat. The endocrine system of a tiny human begins a new phase of its activity.
At this stage, the stability of his pancreas is important. After all, it is she who influences the development of all metabolic processes, as well as its mental abilities. Surfactant production in the lungs gradually stabilizes.
Mom feels the baby’s development more and more every day.
Week 28
The baby's bones are still getting stronger. Alveoli gradually appear in the baby's lungs. The weight of the baby can reach 1 kg. And the height is already at around 38 cm. Having become so large, he begins to realize his cramped position in the mother’s uterus, but no significant activity appears.
Week 29
At this stage, the baby can already do a lot. If you shine a flashlight through the belly, it will notice the light and follow it, this indicates that the eyes are gradually acquiring the ability to focus. He has already established heat exchange and regulation, and the functioning of the immune system is being adjusted.
The baby's skin becomes lighter, the wrinkles gradually smooth out due to the fact that there is more subcutaneous fat. Muscles are actively growing.
Week 30
At this stage, the tiny baby weighs no more than 1.3 - 1.5 kg. His nervous system begins to activate. The liver is preparing to carry out its functions. A girl's heart will beat faster than a boy's.
At this time, the baby’s eyes are open, and his movements become calmer and more meaningful. Most often, at week 30, the fetus occupies the position from which it will subsequently be born. Therefore, it is worth monitoring his movements so that he takes the correct position.
31-40 weeks
31 weeks
At this stage, the baby reaches a weight of no more than 1.5 kg. His internal organs are actively learning to work independently. The liver can already cleanse the blood on its own.
Surfactant, that is, a mixture of surfactants that lines the pulmonary alveoli from the inside, is still being produced. Gradually, a connection between the brain and peripheral nerve cells is established. If the baby decides to touch his eye, he will definitely close his eyes.
Week 32
This is the phase when the baby is actively growing and continuing its development. The organs and systems of his body are establishing their full functioning. The baby is becoming more and more like a normal newborn.
During this period, the baby finally occupies a cephalic presentation. His Skull is still soft.
Week 33
During this period, the baby weighs up to 2 kg. He continues to build up his muscles, gets stronger and forms a fat layer. His body becomes more proportional, his limbs lengthen slightly.
The baby is already able to express his emotions, and many systems of his body are fully functioning. The child is able to express emotions. The kidneys are still only preparing for their main function in the future - the ability to filter.
34 week
These days, the baby's development is almost completely completed. The baby's facial features acquire individual characteristics and become clearer. The baby's gastrointestinal functions are actively developing and improving.
Week 35
This week is characterized by activity in the growth of both muscle and fat tissue by the baby. Every week, the baby continues to gain approximately 220 g. His skin is completely freed from lanugo, and his shoulders are rounded.
Week 36
The baby’s body, which is growing stronger every day, continues on the path of improvement. In his already formed liver the process is underway accumulation of iron. All body systems continue to be fine-tuned for flawless operation. The baby is actively moving in the womb, sucking his finger, preparing to kiss for the first time. mother's breast. By 36 weeks, most expecting babies are lying head down.
Week 37
The baby in the womb has formed, as all vital organs are ready for independent work. The stomach is ready to accept food, the heat exchange process is well established. The lungs are ready to take their first breath outside the mother's body. The baby continues to grow stronger and gain weight.
Week 38
The baby is formed and ready to be born. In boys, the testicles gradually descend into the scrotum at this time. At 38 weeks, babies' skin takes on a pleasant pink tone.
Week 39
Your baby is already fully developed and is often born at 39 weeks, without waiting for the due date. All the baby’s organs are fully capable of independent functioning. The baby responds to light stimuli and is very sensitive to sounds. The skin is completely cleansed of vernix.
Week 40
In the fortieth, final week, the baby is fully formed and ready to be born. His height is already approximately 49-55 cm, and his weight is from 2.5 to 4 kg. Everything will depend not only on how you ate during pregnancy, but also on genetics.
41-42 weeks
Sometimes pregnancy lasts more than 40 weeks, the baby is already post-term. At this time, they resort to artificial stimulation of labor.
All stages of pregnancy and fetal development from conception to birth video
Knowing how your baby is developing in your tummy is simply necessary. This way you can protect yourself from possible complications. Don’t forget to also regularly visit your gynecologist. An experienced doctor will help determine possible deviations during pregnancy and prevent complications.
