Ultrasound during pregnancy is essential, but at what period of time is it actually done? Why? 1, 50 + days after menopause, the purpose is to see the size of the gestational sac, the presence or absence of fetal heart, to rule out ectopic pregnancy and embryonic stasis; 2, 11-13 weeks after menopause, the purpose is to measure the fetal NT value, screening for some congenital and hereditary diseases; 3, 20-24 weeks after menopause, the purpose is the large screening, screening for the presence of structural malformations of the fetus, such as a serious cleft lip and palate; 4, 24-30 weeks after menopause, the fetal cardiac ultrasound The purpose is to screen the fetus for congenital heart disease, most congenital heart disease occurs by chance, not genetic, so don’t take the excuse that there is no such disease in the family and don’t do it; 5, 31-32 weeks of menopause, the purpose is to see if the size of the fetus is in line with the month, and to find out if the fetus is functionally retarded in growth; 6, 38 weeks of menopause, the purpose is to look at the size of the fetus and the existence of the umbilical cord around the neck, whether the amniotic fluid is normal, and to assess the The purpose of the ultrasound is to see if the amniotic fluid is normal and to evaluate the function of the placenta. The purpose of each ultrasound is different, so if many ultrasounds are done in one period due to pathologic factors, it does not replace the next period.