In the mother's belly, the child develops from the ovum, the size of which is not visible to the naked eye, to the newborn. In each trimester of pregnancy, the fetus looks different.
First trimester of pregnancy
After conception, the ovum moves along the fallopian tubes and is introduced into the endometrium of the uterus, at this time cell division and the development of layers of the embryo constantly occur, from which organs, tissues and the amniotic membrane will develop in the future. At 2-3 weeks of development, the future baby has an oval shape measuring 0.2-0.4 mm.
By the 5th week of pregnancy, an ultrasound of the uterus detects an amniotic egg with a size of approximately 18 mm. The size of the embryo in it does not exceed 1.5 mm, the rest of the space is filled by the icteric sac.
In the first trimester of pregnancy, the size of the unborn child increases rather quickly. The embryo almost doubles in size every week. From the 6th week, the rudiments of the fundamental organs are drawn in the embryo, the notochord is clearly visible, the brain is indicated. At the 7th week, the handles are already visible, the eyes are clearly marked, but the tail remains. From the 8th week of intrauterine development, legs stand out.
By the end of the first trimester at a period of 12 weeks, the embryo has the shape of a small child, its coccygeal-parietal size is about 5 cm. During this period, the fetus has clearly visible eyes, mouth, nose, and nails on the toes and hands. The distinctive sexual characteristics of the child are already noticeable, the makings of the sucking reflex appear, i.e. the embryo begins to swallow amniotic fluid.
The free space in the amniotic fluid allows the baby to "swim" freely, he makes infrequent movements with his arms and legs.
Second trimester of pregnancy
During the second trimester, the fetus improves all the inherent organs and systems. The nervous system begins to function more actively, so the fetus responds to external stimuli - it reacts to all sounds, calms down to classical melodies, distinguishes the voices of the parents, squints when bright light hits the mother's belly.
By 18-20 weeks, the pregnant woman begins to feel the baby's movements, so she can distinguish what he does not like. If the expectant mother lies on her side and the fetus is uncomfortable in this position, he will persistently "kick". When mom is nervous, baby is also restless.
At 5-6 months of pregnancy, the baby's skin becomes pink, the face and body are covered with a thin layer of lubricant. During this period, all facial features are clearly visible, eyebrows appear.
By the end of the second trimester, the baby begins to suck on his fingers, actively swallows amniotic fluid. When the diaphragm spasms, the fetus may hiccup. At this stage of intrauterine development, the kidneys and intestines begin to function.
Third trimester of pregnancy
In the last trimester, the baby quickly gains weight and grows. At 24 weeks, the weight of the fetus is about 700 g, the coccygeal-parietal size is 30 cm. By the end of pregnancy, the weight may exceed 3 kg. The growth of the newborn is approximately 50 cm. At this time, the fetus develops subcutaneous tissue, the first folds can already be seen. Many babies actively grow hair on their heads, and they are born with fine curls.
In the third trimester, the baby sleeps and is awake according to his schedule, he already knows how to open and close his eyes.
In the amniotic fluid at this time, the fetus becomes cramped. The child does not move so actively, but more often sticks out the hip or elbow, sometimes you can feel a small heel through the mother's stomach. At 8-9 months, the fetus, as a rule, lowers its head down and prepares for birth.
