In the twenty-first week of pregnancy, the active development of the fetus continues. This period of development of the future child is considered the most favorable period of pregnancy in a woman. Significant changes occur in the skin of the future child.
The skin thickens considerably and gradually acquires the usual color of human skin. The fetus begins to form and deposit subcutaneous fat, which is the main energy reserve for the unborn child.
Since the fetus is still quite small in size and there is enough room in the uterus for it to move around, the fetus makes various movements inside the uterus and often changes its position. Sometimes it turns its head downward and hangs in this position. It may also take a transverse position inside the uterus. Sometimes the fetus takes a head-up position. All these positions are not permanent and the fetus does not stay in each of them for long.
Despite the fact that the fetus in the twenty-first week of pregnancy is still very small, the subcutaneous fatty tissue in this period continues to accumulate very actively in the future child. The arms and legs of the fetus are gradually becoming chubbier and more developed, they appear noticeable folds.
The development of the nervous system of the future child becomes so active and effective that the fetus begins to swallow amniotic fluid.
Modern research by neurophysiological scientists shows that during the twenty-first week of a woman’s pregnancy, her unborn child begins to recognize the phases of sleep and wakefulness. These periods begin to alternate more or less regularly. The sleep of the fetus is sometimes more, sometimes less deep. In total, the fetus sleeps about sixteen to twenty hours every day.
This alternation of sleep and wakefulness phases in the fetus has the most favorable effect on the current and subsequent development of the nervous system of the future child.