Formation of the fetal brain - stages
The fetal nervous system is formed 13 days after fertilization; on the 28th day, the formation of the brain and spinal cord begins; if the closure of the neural tube does not occur at this stage, the child is born with anencephaly. To avoid pathology, doctors recommend taking folic acid (vitamin B9) even during pregnancy planning; the vitamin reduces the development of the defect by 70%.
Intensive brain growth begins from the 7th week of pregnancy; iodine will provide additional support for its healthy development. The iodine content in the mother's body depends on the production of thyroid hormones; its deficiency leads to impaired mental abilities of the child. The recommended amount of iodine in the diet of a pregnant woman is 150-200 mcg per day.
Some medications, chemicals and infectious diseases negatively affect the development of gray matter.
At week 17, the formation of cells responsible for recognizing external stimuli, such as taste, light, smell, sound or touch, begins; electrical impulses are transmitted faster than before. At approximately 26 weeks of pregnancy, important nerve pathways appear that transmit impulses from the eyes, ears, muscles and skin to the “main center” of the body; the first grooves are observed on its surface. Reaction to light and sound is determined at 25-28 weeks. The ability to sense body temperature and control breathing develops in the third trimester.
Fetal development by week of pregnancy
Fetal development by weeks of pregnancy from 1 to 4
Pregnancy occurs when the female egg merges with the male sperm into a single whole, that is, the formation of a zygote. From this moment, the active development of the fetus begins during the weeks of pregnancy, after which the baby is born.
The first week of pregnancy is spent transporting the egg to the uterus and developing the area, that is, its attachment to the wall of the uterus. Already from the second week of pregnancy, the fetus begins to develop and grow. During this period, the rudiments of the brain and spinal cord appear.
In the third week, all fetal systems begin to form, including the most important organ—the heart. By the end of the third week of pregnancy, the heart muscle will already be functioning. In the fourth week, the formation of the spine, lungs and intestines begins.
Fetal development by weeks 5 to 8
Each week of pregnancy carries with it certain functions and responsibilities, and the fifth in particular. In the fifth week, the fetus already has its first organs, or rather, their foundations. The formation of organs of the nervous, digestive and circulatory systems begins, the outlines of limbs and even marigolds appear, cells are formed, from which the child’s genital organs will later be formed. Also in the fifth week, the ears, eyes, nasal cavity and upper lip begin to appear.
The sixth week of pregnancy is mainly devoted to the development of the baby's heart and brain. In addition, fingers begin to appear, muscles in the face are formed, and the formation of the liver and pancreas is already coming to an end. At the seventh week, you can already see the fingers and eyes, which have taken on the shape of a newborn baby. The baby can move his mouth and arms.
By the beginning of the eighth week, the formation of the umbilical cord has been completed and the process of supplying nutrients through it has been established. The ears, eyelids, lips and nose also complete their formation.
Fetal development by weeks 9 to 12
By the end of the ninth week of pregnancy, the baby can already move his fingers, as joints appear in them. At the tenth week, the baby can reflexively make sucking and swallowing movements, as well as move and turn over in the womb.
The eleventh week of development is notable for the formation of the iris, which is directly related to the color of the child’s eyes. In the seven-day period of the twelfth week, the baby’s breathing process begins to develop, and the genital organs acquire features by which it will be possible to distinguish the baby by gender.
Intrauterine development of the fetus from 13 to 16 weeks
At the thirteenth week of pregnancy, the formation of the circulatory system ends, and therefore at the fourteenth week it is already possible to determine the Rh factor and blood type of the child. In addition, the baby's skin takes on a pinkish tint, due to the fact that blood is already circulating throughout the child's body.
At the fifteenth week, the baby is already producing urine, as the final formation of the kidneys and bladder occurs. The sixteenth week makes the baby’s body capable of functioning sweat and sebaceous glands.
Fetal development from 17 to 20 weeks
At the seventeenth week, the child already hears the mother’s voice, breathing and sharp sounds heard “outside the mother”, which, by the way, irritate him. The eighteenth week often becomes a joyful event for parents, since the kicks made by the baby can be felt through the mother’s belly.
The nineteenth week is the final formation of the adrenal glands and endocrine system. At the twentieth week, the baby is already smiling and blinking his eyes. In addition, the baby can already bring his hand to his mouth and suck his finger.
Intrauterine development of the fetus from 21 to 24 weeks
During the twenty-first week of development, you can observe how the baby explores himself and the surrounding space, that is, he feels his body and the walls of the amniotic sac. Week 22 - the baby swallows amniotic fluid and takes more frequent breaths. Week 23 - the baby reacts not only to loud sounds, but also to bright light, which indicates that his vision has developed. Week 24 - the beginning of active work of the heart, and consequently, an increase in its size.
Fetal development from 25 to 28 weeks
Week 25 - the cartilages that still serve as the skeleton are strengthened and turn into bones, the baby’s hair can already grow.
At the 26th week of development, the baby begins to smell the odors that appear in the amniotic fluid from the mother’s diet.
At week 27, any hemisphere of the brain begins to function, which means it is already possible to determine whether the child will be born right-handed or left-handed.
At week 28, subcutaneous fat forms, causing the baby’s skin to stretch and straighten.
How the fetus develops in weeks 29-32
At the twenty-ninth week, the baby is already establishing a relationship with his mother, or rather, begins to depend on her even more than before. During the period of 29-30 weeks, an emotional connection is established between mother and fetus. That is, the child experiences all the same feelings as his mother.
Starting from the thirty-first week, the baby has a functioning endocrine system that produces hormones, including the hormone that promotes milk production in the mother’s body. 31 weeks - 32 weeks - active development and increase in brain size occurs.
How the fetus develops in weeks 33-36
At the thirty-third week, the nails on the arms and legs become formed and continue to grow. At week 34, active strengthening of all bones continues, with the exception of the cranial bones, which will become stronger after childbirth. Also, the hairs acquire a certain shade. At week 35, the baby’s skin acquires a natural shade, due to the improvement of the blood and its preparation for the independent functioning of the body. At week 36, all internal organs are finally formed and prepared for childbirth.
Fetal development from 37 to 40 weeks
Yes, yes, exactly the tenth month of pregnancy. Many mothers believe that pregnancy lasts exactly nine months, but in reality this is not the case. The thing is that doctors count nine months, since they record the beginning of pregnancy from the moment of the last menstruation. In fact, conception usually occurs not at the beginning of the menstrual cycle, but in the middle. In this regard, pregnancy proceeds without pathologies for 40 weeks.
Starting from the thirty-seventh week, the baby’s body begins to prepare for its birth. The baby is actively starting to gain weight, or rather, he gains about 35 grams per day. The child's nails grow long enough to provide protection for the fingers. At 38 weeks, the baby’s stomach is already functioning, passing amniotic fluid through itself and preparing to process breast milk. Also during this period, the baby drops down in the abdomen.
39 weeks - the baby develops a sense of taste. The baby may wince if he swallows amniotic fluid that contains food that the mother consumed and did not like. At the fortieth week, the baby is completely ready for independent existence, and therefore his own birth.
How does maternal nutrition affect
The fetal brain is growing rapidly and assistance in its proper development will never hurt. The benefits of folic acid and iodine were mentioned above; nutritional supplements such as omega-3, B vitamins and iron will also not be superfluous. Iron determines blood volume, helps deliver nutrition to the placenta and improves the maturation of the fetal brain. Before taking iron supplements, you should make sure you are deficient.
The norm of vitamin B6 for expectant mothers is 1.9 mg per day; it is responsible for the proper development of mental abilities and the nervous system. Foods high in B6 - buckwheat, red bell pepper, potatoes, leafy vegetables, meat. Omega-3 also plays an important role, and in particular DHA, which is part of healthy omega fatty acids. Studies have shown that DHA is the main building material for the brain; its norm during pregnancy is 400-600 mg per day. Foods high in omega-3 include fish, nuts, flaxseed and canola oil.
A great way to indirectly influence developmental milestones is through exercise. Regular exercise strengthens the body, improves blood circulation and helps to calm down.
Embryo growth in the second obstetric month
During the fifth week, the following are formed:
- eyes, inner ear;
- nervous system;
- the circulatory system develops;
- pancreas;
- digestive system;
- nasal cavity;
- upper lip;
- limb buds
During this same period, the formation of sex in the fetus occurs. Although it will be possible to determine whether a boy or a girl will be born much later.
During the sixth week, the development of the cerebral cortex continues, and facial muscles begin to appear. The base of the fingers and nails is formed. The heart is divided into two chambers, next in line are the ventricles and the atrium. The liver and pancreas are almost formed. The weight of the fetus changes slightly during the weeks of pregnancy at first; active growth of the embryo begins in the fourth month.
The seventh week is significant because the umbilical cord has completed its formation completely, and now nutrients are supplied to the fetus with its help. The embryo can already open its mouth, eyes and fingers have appeared.
This month the following changes occur in the fetus:
- a nasal fold appears;
- ears and nose begin to develop;
- the membrane between the fingers disappears
Fetal period of intrauterine development of the fetus
At weeks 9 and 10, development continues. Now the embryo is able to open and close its mouth and even grimace. From the 11th week, the unborn baby enters a new stage, from which it is usually called a fetus. From this point on, ultrasound examinations are carried out, thanks to which biometric data and activity are assessed. At the same stage, the brain structures become noticeable, and the facial bones and eye sockets are partially visible.
At week 12, the fetus grows to 60 mm. Moreover, its body weight reaches 20 g.
The size of the fertilized egg during this period almost completely corresponds to the size of the uterus. The genital organs of the fetus develop in accordance with the feminine and masculine principles. The digestive and nervous systems are improved. Leukocytes begin to be produced in the blood. Also at week 12, imitation breathing appears.
Click on the picture to enlarge.
By the 13th week, the limbs acquire a clear shape, and the first ossifications appear in the bones.
At the 16th week of pregnancy, the length of the unborn baby reaches 12 cm with an average body weight of about 100 grams. At this time, a routine ultrasound is performed, since almost all organs can now be clearly differentiated. The purpose of the study is also to exclude any fetal pathologies. In addition, all impatient mothers can already find out the gender of their unborn baby.
By the end of the 20th week, the fetus gains up to 300 grams and grows up to 26 cm. Its skin has a red tint and is abundantly covered with hair. Also at this time, the unborn baby produces meconium - the original feces.
If a woman is expecting a baby for the first time, then she feels the long-awaited movements and tremors exactly at the 5th month of pregnancy. Those who already have children feel the baby’s activity 2 weeks earlier.
At the 6th month of pregnancy, the baby reaches 30 cm in length, and its weight ranges from 600 to 700 grams. He is already capable of performing respiratory manipulations, and in case of prematurity, his life can be maintained in the extrauterine environment, subject to special therapeutic conditions.
Sixth month of pregnancy
The formation of the fetus in the weeks of the sixth month is marked by an increase in the time when the child is awake. He begins to show interest in his body. This involves touching the face, tilting the head.
The fetal brain continues to develop, neurons work at full capacity. The heart muscle increases in size, the blood vessels improve. During this period, the baby learns to breathe, the number of inhalations and exhalations increases. The lungs have not yet completed their development, but alveoli are already forming on them.
The sixth month is significant because at this time an emotional connection between the child and mother is established. All feelings experienced by a woman are transmitted to the baby. If a pregnant woman experiences fear, the fetus will also begin to behave anxiously. Therefore, it is recommended that the expectant mother avoid negative emotions.
At the twenty-fourth week, the baby’s eyes and hearing are fully formed. He can already respond to various sounds.
Fetus at 33–36 weeks of pregnancy
The formation of the fetus during this period approaches the final stage before childbirth. His brain is actively functioning, his internal organs work almost like those of an adult, his nails are formed.
During the 34th week, the baby's hair grows; it is now that his body so needs calcium for the proper development and strengthening of bones. In addition, the child’s heart enlarges and vascular tone improves.
At week 36, the little person takes a position in which his head, arms, and legs are pressed against his body. By the end of this period, the child is fully matured to exist outside the womb.
