Early Down, or early Down’s syndrome screening, has important indicators such as fetal NT test and maternal serologic indicators. Early Down’s syndrome screening is a test performed around 12 weeks of gestation, with the main purpose of screening the fetus for chromosomal abnormalities. The main testing indicators of early Down’s screening include fetal NT value via ultrasound and biochemical tests. The biochemical tests screen for maternal serologic levels of molecules such as pregnancy-associated plasma protein A and beta human chorionic gonadotropin. In clinical practice, Down’s syndrome screening is divided into early Down’s syndrome screening and mid-pregnancy Down’s syndrome screening. If the results of early Down’s syndrome screening are low-risk, mid-pregnancy Down’s syndrome screening is recommended, and the results of the two screenings will be combined to determine whether the next step should be taken. If Down’s syndrome is found to be abnormal in early pregnancy, it is recommended that other genetic tests be performed for further judgment.