(1) Ultrasound examination in the third trimester to determine the site and number of pregnancy levels and to check the gestational weeks. (2) From 4 to 7 months of gestation, at least 1-2 prenatal ultrasound examinations, including 14-20 weeks of gestation: Down’s syndrome screening NT value, 22-26 weeks of gestation ultrasound screening for malformations, etc.; (3) From 7 months of gestation, routine ultrasound examinations, focusing on cranial, fetal heart, liver, kidney and other organs, etc.; (4) From 8 months of gestation, at least 1-2 routine ultrasound examinations, focusing on (4) at least 1-2 routine ultrasound examinations above 8 months, focusing on fetal heart, umbilical blood flow and amniotic fluid AFI values, etc.