So, note that the duration of pregnancy is equal to forty weeks or ten obstetric months, each of which consists of 28 days. Counting the same pregnancy begins with the first day of the menstrual cycle. Thus, the development of the child from the moment of fertilization lasts not forty weeks, but approximately thirty-eight. But, nevertheless, since the formation of a new egg and its development begins a little earlier, and after fertilization, its further development takes place, then the counting starts from the beginning of the month.
But we will not describe the process of egg maturation, but we will begin our "story" from the moment of fertilization. So, after the moment of fertilization in the cell, there are initially only two nuclei, consisting of an egg and a sperm. Moving towards each other, these nuclei merge, thus forming a unicellular embryo, called a zygote.
Intrauterine development of a person consists of three main periods: blastogenesis (first 15 days), fetal period of intrauterine development (before the twelfth week of pregnancy ) and fetal (fetal) period of intrauterine development.
So, after 30 hours from the moment of fertilization, the first division of the zygote takes place. In the following days, there is again one division. On the fourth day, when the fetus, as a rule, reaches the uterus, it is a lump consisting of 8-12 cells. In the next three days, the embryo swims into the uterine cavity, and here the process of division occurs much faster. By the middle of the sixth day the embryo consists of more than a hundred cells. Approximately by the seventh day the embryo is ready for implantation into the uterus cavity prepared at the same time, which is a loose medium swollen and thickened. It takes about forty hours to implant the embryo! By the end of the second week of intrauterine development, the posterior part of the embryo thickens, since the process of laying axial organs begins in it.
At the end of the fourth week of pregnancy, you wonder what happened to the monthly ... Therefore, there are conjectures that you are pregnant. Some women feel their new condition intuitively a little earlier. As a result, malaise and dizziness may appear, as well as increased appetite or the desire to eat something unusual. Your baby already on the third day after fertilization began to produce hCG (human chorionic gonadotropin). It is all pregnancy tests that are sensitive to this hormone. Approximately 10-14 days after fertilization, the level of this hormone rises to the limit of sensitivity of these tests. Within the fourth week the future child (zygote) becomes an embryo. At the end of this week, the child reaches a size of 0.4-1 mm, the size of a small grain of sand.
In the fifth week you can begin to feel increased fatigue, increases the sensitivity of the mammary glands. If last week the child consisted of two layers of cells, endoderm and ectoderm, then this week will be added the third - mesoderm. In the future, the ectoderm will turn into a nervous system, skin, hair and tooth enamel. Endoderm will develop into the digestive tract. Mesoderm is the basis of the skeleton, muscle, blood, excretory and reproductive systems. By the end of the week, the nerve cell is already visible in the ectoderm, and in the mesoderm - the dorsal string. In addition, the heart tube is laid. On the back of the embryo, a groove is formed, which, folded, turns into a neural tube. The neural tube in the process of development becomes a chord, as well as the spinal cord and the entire nervous system. Therefore, it is very important as soon as possible, even at the stage of pregnancy planning, to start taking folic acid, which promotes the safe formation of the child's neural tube.
The bag, the embryo itself and the surrounding membranes with liquid have a size of one centimeter. Your future child occupies only 1.5 mm in this small space.
Many women in the sixth week of pregnancy for the first time visit a gynecologist to make sure of their "interesting situation". From the sixth week begins an important period of laying and forming the main internal and external structures of the child - organogenesis. It lasts until the tenth week, although, in fact, the development of the internal organs of the baby will continue to actively continue after childbirth. On the sixth week the child takes the C-shape. This week there are tiny branches - these are the future arms and legs, as well as the head rudiment with prominent pits and thickenings, from which the eyes, ears and spout will subsequently develop. On the sixth week, many organs and tissues of your child are laid: the primary intestine, the rudiments of bones and cartilages of the axial skeleton, thyroid gland, kidney, liver, pharynx, and also striated muscle and axial skeleton. By the end of this week, the head end of the neural tube closes. Even now your baby has a length of rice grains - 4 millimeters. His heart beats and is perfectly visible with ultrasound.
In the seventh week of pregnancy, many women begin to feel increased nausea in the morning, and also react sharply to various smells.
During this period, the head grows most rapidly because of active development of the brain. The head is rounded, the eye sockets become visible. The mouth begins to form. There is an active development of the child's respiratory system: lumps on the end of the trachea bifurcate into bronchial branches, which later develop into right and left bronchi. The heart begins to separate into chambers and arteries. Veins appear, a gallbladder and spleen form. Your child has already reached the size of a pea, it's as much as 8 mm!
On the eighth week of pregnancy, you can use ultrasound to track the first spontaneous movements of your child. In this period, the auricles, the spout and even the upper lip are already emerging. There are hands and fingers on them, but the lower limbs will develop later. By the end of this week, the embryo has a length of 13 mm, when measured from the crown of the head to the base of the buttock. This size is a lake prawn.
At the ninth week , the main changes in the arms and legs can be observed. The fingers are determined, though, they are still short, thick and membranous. The skeleton is represented by a cartilaginous tissue, but the formation of bone tissue begins in the arms. With ultrasound examination, you can observe the bending of the knees and elbows, as if the baby is waving them. During this period, the eyelids appear, the neck has developed, the head is no longer the same as before, pressed to the chest. Gradually, the role of the placenta is determined: it delivers the baby food from you and gives you back the waste products of a small vital activity. Your child has grown considerably, now his length is 18 mm, like a cashew nuts.
The tenth week of intrauterine development is the final week of the embryonic period of intrauterine development. After this week and until the birth itself, a child in obstetric terminology is called a fetus, but this is for doctors. For us, he is from the very beginning a child, a kid and nothing else ...
At this period, fingers separate because of the disappearance of the membranes between them. Noticeably decreases, and by the beginning of the eleventh week disappears completely, the tail. The child acquires a human face. The external genitalia are still indistinguishable, but the boys are already starting to develop testosterone.
The eleventh week. Now the head of the child is approximately equal to half the length of his body. The eyes of the child are widely distributed, the ears are located low, and the legs are still very short compared to the length of the body. From the eleventh week, the kidneys begin to function: they produce urine. The liver now makes 10% from weight of all body. The length of the child is 5 cm with a weight of 8 grams.
It is generally believed that already from this period of pre-natal life the child feels much of what the mother feels. Some experts are inclined to the view that "the foundations of the individual are already being laid".
The twelfth week is the period when the future child is already formed for further growth and development. There was a bookmark of all organs and systems - the main stage of intrauterine development. Male and female genital organs will be distinguishable only after a couple of weeks. With ultrasound, you can observe those "acrobatic tricks" that the kid does. And it's not surprising: the child is very active, but there are still very many places for movements. The growth of the child by the end of this week is approximately 6 cm, and weight - 14 grams. And this is not the size of a small pea, but a large chicken egg!
The thirteenth week is the last week of the first trimester of pregnancy. This week the intestine of the child is completely located in the abdominal cavity. The child feels great in the aquatic environment - the amniotic fluid. Nutrition and oxygen he receives through the umbilical cord in a sufficient amount for growth and development. The length of the child is approximately 7 cm, and the weight is 30 grams.
At the fourteenth week, the cartilage, of which the future skeleton of the child was, turns into bones. Hands have a length proportional to the length of the body, but the legs in their growth still noticeably lag behind. The child is already yawning and sucking a finger, and also tumbling. The length of the child is approximately 8.5 cm, weight - 45 grams.
Fifteenth week. The volume of movements of the child's limbs becomes much wider than in the previous periods of development. Transparent skin of the baby radiates thin blood vessels. Handles are compressed into tiny fists. The bones continue to develop, as well as the bone marrow. The length of the child is 10 cm and weighs 78 grams.
On the sixteenth week with the help of ultrasound, you can observe how the child moves his eyes. The head is kept higher due to the fact that the neck has developed well. The ears are already in their final position, their eyes are shifted to the center. This week, the legs become proportional to the length of the body. Start growing their tiny nogatochki. The baby weighs 110 grams, its length is 12 cm.
The seventeenth week. The body of the child is covered with a thin primary fluff - lanugo. The original lubricant, which is produced by special glands, protects the skin of the baby from the water environment. This week, the foundation of future fingerprints, which are determined genetically, are laid. The placenta actively fulfills its main mission: it supplies the baby with oxygen and nutrition and takes away the waste products of vital activity. By the end of the week the child grows to 13 cm and weighs about 150 grams.
The eighteenth week . Your child is still very small and thin, subcutaneous fat has not yet appeared. Nevertheless, with every day, all the features of the face are more clearly visible. The baby already knows how to hear sounds that come through the amniotic fluid, although he hears them vaguely. At the moment, the number of follicles, the future ovaries, in the ovaries of girls is about 5 million, but this number will already be reduced to 2 million by birth, and only a small part of this number will mature throughout life.
The length of the child is 14 cm and weighs 200 grams.
From the nineteenth week the child's growth begins to slow down gradually. Now the process of laying down subcutaneous fat starts, which acts as an important source of heat for the newborn. Develop lungs, grow bronchioles, but for the time being the respiratory system of the child is not able to function without the help of the mother's body.
Despite the fact that the baby's eyes are closed, he is already able to distinguish light from darkness. By the end of this week, the baby already grows to 15 cm and weighs 260 grams.
The twentieth week. Your child already knows how to yawn, suck a finger, play with the umbilical cord, and the boys even manage to play with their penis. Girls have already formed the uterus, the vagina is still at the stage of formation. Now the child weighs 320 grams and has a length of 16 cm.
The twenty-first week of intrauterine development. The kid can swallow the amniotic fluid. The rudiments of dairy and permanent teeth are already formed. The movements of the child are becoming more active. The baby has grown to 17.5 cm and weighs 390 grams.
The twenty-second week. The baby continues to grow hair on his head, the crooks appear. Pigment responsible for hair color, will begin to form a little later. Many mothers already feel the movements of the child. The weight of the baby is 460 grams, height - 19 cm.
The twenty third week. If earlier the baby grew more active, now he begins to actively increase weight. Baby sees dreams. This is evidenced by rapid movements of the eyes, reminiscent of the active sleep phase in an adult. Thanks to this active movement of the eyes, the development of the brain is stimulated. If you listen to the pregnant belly with a tube, you can hear the baby's heartbeat. Now the baby weighs on average 540-550 grams with a height of 20 cm.
Twenty-fourth week. The muscular system and internal organs of the child are further developed. If the child is born now, then he will be viable, although he will need special living conditions. Until this time, the lungs did not function yet, but now terminal caps are formed at the ends of the capillaries, which are separated by a thin film from the alveoli. Now, a surfactant, a surfactant, is produced, thanks to which a thin film is formed on the walls of the capillary sacs, why they do not stick together under the influence of respiration.
The child grew to 21 cm and weighs an average of 630 grams.
The twenty-fifth week. In the intestine of the baby, the original feces continue to form and accumulate, which is called meconium. If you are skinny, then the movements of the baby can already be felt by outsiders, putting a hand to your tummy. The child's length already reaches 28 cm, and the weight is 725 grams.
Twenty-sixth week. The baby's skin is still red and wrinkled. Despite the fact that subcutaneous fat continues to accumulate, the baby is still very thin. Due to the presence of sufficient amniotic fluid and small size of the baby, it has the ability to actively move. The child reacts to external sounds, as well as changes in the position of the mother's body. The tongue has already formed taste buds, due to which already at this stage of intrauterine development certain taste preferences are formed, for example, love of sweet. Now the baby weighs about 820 grams and has a height of 23 cm.
The twenty-seventh week. This is the beginning of the third trimester of intrauterine development of a small man. All systems of organs have already been formed and are actively working, at the same time they continue to develop actively in a favorable environment. The last three months is the period of active growth and development of the child's brain.
The twenty-eighth week. The child by this time of pregnancy has already grown to 35 cm! Now it weighs 900-1200 grams. Due to the fact that the subcutaneous fatty tissue in the child is still very poorly developed, his skin has a wrinkled appearance. The entire body of the baby covers the hair of the dog. And on the head, the hairs reach a length of 5 mm. Baby's shorts are tender and tender. Sometimes the little one opens his eyes. In boys, by this time, the testicles from the abdominal cavity have not yet descended into the scrotum, and the girls have large labia not yet covered by the small ones.
The twenty-ninth week. Begins to work and develop the immune system of the child. Enamel appears on the rudiments of future teeth. The frequency of the baby's heart rate is 120-130 beats per minute. The baby hiccups, while the mother feels light rhythmic tremors. A child born at this time can survive if there are favorable conditions. The baby has grown to 37 cm and weighs 1150 g.
The thirtieth week. The kid knows how to react to the bright light that shines through the belly. The lungs of the baby continue to develop, thanks to the "breathing exercises" of the chest. Now the child weighs about 1300 g with an increase of 37.5 cm.
Thirty-first week. The fat layer under the skin becomes thicker, so the baby's skin no longer looks as wrinkled as in previous weeks. The pupillary membrane is no longer present. Some babies already turn the head down during this period. The kid grew to 39 cm and weighs 1.5 kg!
Thirty-second week. All systems and organs continue to develop, including the baby's nervous system. Corners appear on the surface of the brain. Pupils have the ability to narrow in the case of translucent light through the mother's belly.
Thirty-third week. At this stage of intrauterine development in the mother's tummy there is still enough room for movement, but here's a little more, and it will become very, very tight. The kid already has to turn his head down, as very soon there will not be enough space to perform an important somersault for a favorable "going out". The child has a height of 41 cm and weighs 1900.
Thirty-fourth week. If suddenly there is a premature birth, the child will be born viable, but will be considered premature and require a special long-term care. The remaining six weeks of intrauterine development is an important stage in preparation for birth.
The baby's skin is already smooth and pink, thanks to the accumulation of subcutaneous fat, which now amounts to 8% of the child's weight. The baby has grown 43 cm in length and weighs 2100 g.
Thirty-fifth week. The child has grown marigolds, and he can already scratch himself. Some babies are even born scratched. The child continues to actively gain weight. Now it weighs 2300 g with an increase of 44 cm.
Thirty-sixth week. The child, as a rule, fell head down. If he has not already done so, it is unlikely that he will be able to tinker around. Pushkin hair on the body thinning, but the hair on the head is lengthened. The cartilages of the ear shells and spout are compacted. The boys' eggs are already in the scrotum. The average weight of a child is 2.5 kg and height is 45 cm.
Thirty-seventh week. Development the lungs are in full swing, everything is ready for independent breathing. Baby gets 30 grams of fat a day. A child born on this term of pregnancy can scream, succinct and sucking reflexes are expressed. Now he should weigh an average of 2700 g with a height of 46 cm.
The thirty-eighth week. The child is completely ready for birth. If he is born on this date, then on average he will weigh 2900 grams and have a height of about 48 cm. By this time, the baby usually descends into the pelvic cavity, and you feel that it makes you feel better breathing.
Thirty-ninth week. The kid in your tummy is already very tight, his knees are pressed to his chin. Pushkoe hair remained only in the area of the shoulder girdle. The head of the child is covered with hairs that can reach a length of 2-3 cm. The height of the baby is 49 cm, and the weight of 3150 g.
Fortieth week. The movements of the child are slowed down on the eve of birth. The kid's guts are stuffed with meconium, black-green original feces, this is lanugo, dermal scales, amniotic fluid - everything that it swallowed in the process of intrauterine development. The average weight of a full-term newborn baby is 3-3.5 kg, and the height is 48-52 cm.
So we "passed" with you a mysterious and fascinating odyssey of intrauterine development of the child for weeks. From a small cell for nine months a full-fledged little man develops - a great joy for mom and dad. Good luck, baby, good luck!