Down’s syndrome screening between 14-20+6 weeks of pregnancy, preferably at 16-18 weeks, is a very important test to screen for the risk of Down’s syndrome babies by checking the concentration of alpha-fetoprotein, chorionic gonadotropin, and free estriol in the mother’s blood, and at the same time combining with the gestational week, age, and body weight to determine whether there is any problem of an aberrant non-neutral chromosome, which is a very important test that can screen for the risk of Down’s syndrome babies. If the test reveals a high risk, it is recommended to go to the hospital for amniocentesis in time to clarify whether you have a Down’s syndrome fetus. Ultrasound NT test is done between 11-13+6 weeks of pregnancy, and if the NT exceeds 2.5mm indicating a high risk of Down’s syndrome in early screening, it is recommended that it is best to go directly to amniocentesis at 16-18 weeks. It is important to follow your doctor’s instructions to go to the hospital for regular checkups during pregnancy to detect abnormalities in a timely manner.