Many mothers-to-be worry that ultrasound is bad for the fetus, especially during early pregnancy, but there is no need to do so. Studies have shown that there is no direct correlation between multiple ultrasounds during pregnancy and the health of the fetus. If you want to monitor your baby’s growth and development throughout your pregnancy, you need to have at least five ultrasounds throughout your pregnancy. First time: 6 to 9 weeks of pregnancy. This is to determine whether the embryo is inside or outside the uterus, whether it is a single fetus or a twin fetus, and whether it is a gravid fetus. For those who have irregular menstruation, the time of pregnancy will be accurately determined and the expected date of delivery will be determined. The second time: 11-14 weeks of pregnancy. To find out the growth and development of the fetus and whether there are any serious malformations. Measurement of the nuchal translucency (NT), combined with Down’s syndrome screening, can make a preliminary diagnosis of fetal chromosomal disorders. The third time: 20-24 weeks of pregnancy. To understand the fetal growth and development and the position of the placenta. During this period, all organs of the fetus are fully developed, and the ultrasound examination can exclude 85% of the fetal structural abnormalities. The fourth time: 28 to 32 weeks of pregnancy. It mainly plays a role of observation and monitoring. Further exclude problems with important internal organs of the fetus. Fifth: 37th week of pregnancy. To find out the amount of amniotic fluid, fetal activity, and the presence of abnormalities such as umbilical cord encirclement. The doctor also decides whether to deliver the baby by cesarean section or naturally, in conjunction with measurements of the pregnant woman’s pelvis. If there is any abnormality during pregnancy, the doctor will increase the number of ultrasound examinations according to the situation, but of course, it is not better to do more ultrasound, it is better to do as little as possible for unnecessary examinations.