What Makes Congenital Heart Defects More Likely?

What caused your baby’s congenital heart defect? You’ll naturally want to know. But the answer isn’t a simple one because in most cases we just don’t know.

These heart problems form before your baby is born. Genes play a role in some cases. But heart defects can happen for other reasons, too.

Here are some of the things that make these conditions more likely:


If you have diabetes, be sure to keep it well controlled before and during your pregnancy. The condition can affect the formation and growth of your baby’s heart.

Gestational diabetes, which develops during pregnancy, shouldn’t raise your baby’s chance of having a heart defect.

Rubella (German Measles)

You probably were vaccinated against this as a child. (Remember the “MMR” -- measles, mumps, rubella -- vaccine?).

But if you weren’t, or you’re not sure, tell your doctor. If you get rubella during pregnancy, it can create problems with your baby’s heart. If you need to get vaccinated for rubella, you should wait at least a month after getting vaccinated before you get pregnant.

Drinking and Smoking

Both can lead to congenital heart defects and other problems with your baby’s development. Avoid them while you’re pregnant.


If you take any prescription drugs, talk to your doctor if you get pregnant. Some medicines can make heart and other birth defects more likely. Among them are the acne medication isotretinoin and anti-seizure drugs that contain valproate.

Your doctor may be able to switch you to another medicine until your baby is born.


Your baby’s chance of having congenital heart defects rises if either of their parents or any relatives have problems. Talk to your doctor about genetic testing and counseling if it runs in your family.

Genetic testing involves a simple blood test before or during your pregnancy. And it’s important because if you have certain genetic mutations, your child’s chances of having it can go up by as much as 50%.

Your doctor will help you understand what your test results mean. That information may give you peace of mind as you think about your future family. Keep in mind that doctors can treat many of these conditions, and these babies grow up to live long, healthy lives.

WebMD Medical Reference Reviewed by James Beckerman, MD, FACC on August 07, 2020



American Heart Association: “Understand Your Risk for Congenital Heart Defects.”

Mayo Clinic: “Congenital Heart Defects in Children: Risk factors.”

American Heart Association: “Genetic Counseling for Adults with Congenital Heart Defects.”

CDC: “Maternal Vaccines: Part of a Healthy Pregnancy.”

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