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, your heart pumps more blood each minute and your heart rate increases.

Labor and delivery add to your heart's workload, too. During labor — particularly when you push — you'll have abrupt changes in blood flow and pressure. It takes several weeks after delivery for the stresses on the heart to return to the levels they were before you became pregnant.

What are the risks?

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

  • Heart rhythm issues. Minor abnormalities in heart rhythm are common during pregnancy. They're not usually cause for concern. If you need treatment for an arrhythmia, you'll likely be given medication, the same as you would if you weren't pregnant.
  • Heart valve issues. Having an artificial heart valve or scarring or malformation of your heart or valves can increase your risk of complications during pregnancy. If your valves aren't working properly, you might have trouble tolerating the increased blood flow that occurs during pregnancy.

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

  • Congestive heart failure. As blood volume increases, congestive heart failure can worsen.
  • 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 for heart problems occurring during pregnancy and of premature birth.

Do some heart conditions cause more complications than others do?

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

Pregnancy isn't recommended for 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).

What about medication?

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.

How should I 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. You'll likely be referred to an obstetrician who specializes in very high-risk pregnancies (maternal fetal medicine specialist). You might also want to check in 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 treatment changes you might need before you become pregnant.

Certain medications 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 18, 2017 See more In-depth