Birth Defects Causes & Risk Factors

Birth defects occur before a baby is born. Most birth defects occur in the first three months of pregnancy, when the organs of the baby are forming. This is a very important stage of development. However, some birth defects occur later in pregnancy. During the last six months of pregnancy, the tissues and organs continue to grow and develop.

Most birth defects are thought to be caused by a complex mix of factors. These factors include our genes, our behaviors, and things in the environment. For some birth defects, we know the cause. But for most, we don't.

What We Know

We do know that some women have a higher chance of having a child with a birth defect:

  • Women who take certain drugs, smoke, or drink alcohol during pregnancy.
  • Women with certain medical conditions, such as uncontrolled diabetes or obesity before and during pregnancy.
  • Women who take certain medications that are known to cause birth defects, such as isotretinoin (a drug used to treat severe acne).
  • Women who have someone in their family with a birth defect. To learn more about your risk of having a baby with a birth defect, you can talk with a clinical geneticist or a genetic counselor.
  • Women over the age of 35 years.

Visit the Centers for Disease Control & Prevention website for more facts about birth defects.

Questions?

If your child was born with a birth defect, your child's doctor may have discussed with you the specific aspects of your child's medical condition. However, there may be additional services and support available to you, your child, and your family.

Visit our Resources for Families page for a list of resources that may be useful. If you have any questions, please contact your doctor or our Growing Up Healthy Hotline at 1-800-522-5006.

If you are a health care professional or researcher, visit our Resources for Health Professionals & Researchers page.