If you have any risk factors for having a fetus with a birth defect, talk with your health professional or a genetic counselor to help you decide which screening or diagnostic tests will be useful for you. The following are risk factors for having a fetus with Down syndrome or certain birth defects:

• You or your partner has a family history of or has a child with Down syndrome, a neural tube defect, or any genetic disorder or birth defect. But most infants with neural tube defects or Down syndrome are born to families without any risk factors for the disorders.
• You or your partner has an abnormal chromosome arrangement (a particular type of genetic disorder).
• You have diabetes.
• You have used a medicine that is known to cause birth defects. Talk to your doctor about any medicine you have taken in the months before or during your pregnancy.
• You will be age 35 or older on your due date. The risk of having a baby with Down syndrome increases with the mother's age.

Women with known risk factors are usually offered a chorionic villus sampling in the late first trimester or an amniocentesis in the second trimester. If you have an amniocentesis, a triple screen test for Down syndrome and birth defects is not necessary.