Heart conditions and pregnancy: Know the risks

Pregnancy stresses your heart and circulatory system, but many women who have heart conditions deliver healthy babies. Know the risks — and how to help prevent complications.

By Mayo Clinic Staff

If you have a heart condition, you'll need special care during pregnancy. Here's what you need to know about heart conditions and pregnancy.

How does pregnancy affect the heart?

Pregnancy stresses your heart and circulatory system. During pregnancy, your blood volume increases by 30 to 50 percent to nourish your growing baby. The amount of blood your heart pumps each minute also increases by 30 to 50 percent. Your heart rate increases as well. These changes cause your heart to work harder.

Labor and delivery add to your heart's workload, too. During labor — particularly when you push — you'll experience abrupt changes in blood flow and pressure. When your baby is born, decreased blood flow through the uterus also stresses your heart.

What are the risks?

The risks depend on the nature and severity of the underlying heart condition. For example:

  • Heart rhythm issues. Minor abnormalities in heart rhythm are common during pregnancy. They're not usually cause for concern.
  • Heart valve issues. If you have an artificial heart valve or your heart or valves are scarred or malformed, you might face an increased risk of complications during pregnancy. If your valves aren't working properly, you might have trouble tolerating the increased blood flow.

    In addition, artificial or abnormal valves carry an increased risk of endocarditis — a potentially life-threatening infection of the lining of the heart and heart valves. Mechanical artificial heart valves also pose serious risks during pregnancy due to the need to adjust use of blood thinners and the potential for life-threatening clotting (thrombosis) of heart valves.

  • Congestive heart failure. As blood volume increases, congestive heart failure can get worse.
  • Congenital heart defect. If you were born with a heart problem, your baby has a greater risk of developing some type of heart defect, too. You might also be at risk of premature birth.

Do some heart conditions cause more complications than others do?

Certain heart conditions, including problems with the mitral valve or aortic valve, can pose life-threatening risks for mother or baby. Depending on the circumstances, some heart conditions might require major treatments — such as heart surgery — before you try to conceive.

The risk of pregnancy in women who have the rare congenital condition Eisenmenger's syndrome or high blood pressure that affects the arteries in the lungs and the right side of the heart (pulmonary hypertension) is so high that pregnancy isn't recommended.

What about medication?

Any medication you take during pregnancy can affect your baby. Often the benefits outweigh the risks, however. If you need medication to control your heart condition, your health care provider will prescribe the safest medication at the most appropriate dose.

Take the medication exactly as prescribed. Don't stop taking the medication or adjust the dose on your own.

What should I do to prepare for pregnancy?

Before you try to conceive, schedule an appointment with your cardiologist and the health care provider who'll be handling your pregnancy. Also meet with other members of your health care team, such as your family doctor. Your medical team will evaluate how well you're managing your heart condition and consider any treatment changes you might need to make before pregnancy begins.

Certain medications commonly used to treat heart conditions aren't used during pregnancy. Depending on the circumstances, your health care provider might adjust the dosage or make a substitution and explain the risks involved.

July 11, 2014 See more In-depth