The difference between 38+1 and 38+4 pregnancies is not significant, as there is a three-day difference in gestational weeks, but at this time, the fetus is already full-term, and its development has been perfected, and the fetus is basically viable after birth. Usually, the week of pregnancy is calculated from the date of the last menstrual period, and the whole period is 40 weeks, i.e. 280 days. However, women’s menstrual cycle fluctuates, with an average of 28 days, but 28±7 days is normal, so the week of pregnancy can be verified by ultrasound in the early stages of pregnancy. From 37 weeks to 41+6 weeks of pregnancy, the fetal blood system, digestive system, endocrine system and urinary system are all well developed, and the fetus can basically survive after birth. After reaching 42 weeks of pregnancy, it belongs to overdue pregnancy, instead, some diseases will appear, such as fetal overcooking syndrome.