Down’s syndrome screening is best done at 15-20 weeks of pregnancy. Down’s syndrome screening is done mainly by taking the blood of the pregnant woman and by detailed testing of her serum. This is combined with the pregnancy cycle, due date, current age and weight during pregnancy to calculate the risk factor of the fetus having a congenital defect. However, there are actually two types of screening tests for Down’s syndrome, which can be done in early pregnancy, i.e. at 12 weeks of pregnancy, or in the middle of pregnancy. However, most pregnant women are not aware that they can have Down’s syndrome screening early in their pregnancy, so they choose to have it done at 15-20 weeks of pregnancy. If the result of Down’s syndrome screening shows high risk, it means that the fetus is more likely to have the disease and further amniocentesis is needed for non-invasive DNA testing. If the test result shows low risk, it means that the fetus is less likely to have the disease.