Q&A: Birth Defect Risks?
First, remember that an increased risk isn't an assurance that baby will actually have a genetic or chromosomal disorder... just as a totally normal risk doesn't mean baby won't. Evaluate your own risk by looking back at the family history of both you and your husband. Your future child is at heightened risk of any disorders that show up here. If either of you are carriers for a genetic disorder (carrier screenings can detect this) or you’ve already had a child with a defect, your baby’s odds also increase. Other factors that heighten risk are your age (baby’s likelihood of having a defect rises as you age, particularly once you hit 35) and whether you took specific medications at the time of conception or had diabetes prior to getting pregnant. You may also be asked to consider diagnostic testing if a routine prenatal test such as ultrasound, nuchal translucency screening or the triple/quad screen suggests a potential problem.
American College of Obstetrics and Gynecologists. Your pregnancy and birth. 4th ed. Washington, DC: ACOG; 2005.