How many ultrasounds are needed during the October pregnancy and is it necessary to have an ultrasound during early pregnancy? This is often a question that pregnant mothers want to know. It is necessary to perform an ultrasound around 6 weeks of pregnancy, because at this time it is possible to observe the position of the gestational sac (intrauterine or extrauterine), assess the gestational age and the survival status of the embryo. From 11 to 14 weeks of gestation, ultrasound examination of fetal head and hip length, fetal heart rate, and measurement of the thickness of the posterior nuchal translucency (a soft ultrasound indicator of trisomy 21) is performed to rule out anencephaly, umbilical bulge, and other malformations as early as possible; from 20 to 24 weeks of gestation, systematic screening for fetal malformations is performed; around 30 weeks of gestation, fetal development is evaluated again; from 36 to 40 weeks of gestation, final evaluation of fetal position, fetal size, and amniotic fluid index is performed to guide the choice of delivery method. The final assessment of fetal position, fetal size and amniotic fluid index will be performed at 36-40 weeks of pregnancy to guide the choice of delivery method. These four ultrasound examinations are routinely performed during pregnancy and should be performed at any time if there are any abnormalities during pregnancy.