Fasting is not generally required for Down’s syndrome screening, although some hospitals may recommend fasting in order to exclude special dietary interferences or to have blood drawn and biochemical tests performed at the same time. Down’s syndrome screening is a mandatory test during pregnancy and is performed between 15 and 20 weeks after pregnancy. It is performed by drawing the peripheral blood of the pregnant woman and testing the blood levels of chorionic gonadotropin, alpha-fetoprotein and free estriol to screen out those whose fetus is at high risk of Down syndrome. Prior to the Down’s syndrome screening, pregnant women need to provide detailed personal information, such as menstrual cycle, height, weight, family history, whether they smoke, and whether they have a history of ectopic pregnancy, etc. The doctor will need to make a comprehensive assessment based on this information. If the Down syndrome screening suggests high risk, further amniocentesis is needed to confirm the diagnosis. If the amniocentesis test confirms a fetal chromosomal abnormality, it is recommended to induce labor and abandon the fetus as soon as possible.