Down screening is also known as Down’s syndrome screening. A low value in one of the Down’s syndrome screening tests does not mean anything, and the risk value has to be determined in the context of the overall test. Down’s syndrome screening involves taking the mother’s and baby’s serum to measure the concentrations of alpha-fetoprotein, human chorionic gonadotropin, free estriol, and inhibin A. Based on the increase or decrease in these indicators, and taking into account the date of delivery, age, weight, and week of gestation at which the blood is collected, the birth risk coefficient for Down’s syndrome is calculated. One of these values in the serum drawn from the mother and baby may be low, and a low value alone does not tell us anything; it has to be evaluated in the context of the overall situation. Down’s syndrome screening gives low, critical and high risk results according to the stage values, with low risk requiring normal labor and delivery testing, and critical or high risk requiring amniocentesis and systematic ultrasound to further confirm the diagnosis. Clinical for Down’s syndrome screening results judgment doctor will inform, want to accurately understand the results, it is recommended to consult a doctor.