Down screening refers to Down’s syndrome screening, and pregnant women can drink water when they undergo Down’s syndrome screening. Pregnant women undergo Down’s syndrome screening, which is mainly done by drawing blood from the pregnant woman and checking for alpha-fetoprotein, free estriol, human chorionic gonadotropin, pregnancy-related plasma protein A and other items. Drinking water usually has no effect on the test results, so pregnant women can drink water during Down’s screening. Through the Down’s syndrome screening, it can make auxiliary judgment on the fetal 18-trisomy syndrome, 21-trisomy syndrome and neural tube malformations and other diseases, and provide a strong supporting basis for clinical diagnosis and treatment. It is necessary for pregnant women to choose the right time for Down’s syndrome screening under the guidance of professional doctors.