time from the 22nd week of intrauterine life of the fetus (normal body weight is 500 g) to the 7th day inclusive (168 hours) of extrauterine life. The perinatal period is important for human development, since by the end of pregnancy the intrauterine formation of the fetus ends, during the process of childbirth, the fetus is exposed to many factors, and during the first 7 days it undergoes adaptation to extrauterine life.