Heart conditions and pregnancy: Know the risks

Pregnancy stresses the heart and circulatory system. But many pregnant people 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 to know.

How does pregnancy affect the heart?

Pregnancy makes the heart and blood vessels work harder. During pregnancy, blood volume increases by 30% to 50% to nourish the growing baby. The heart also pumps more blood each minute, and the heart rate increases.

Labor and delivery add to the heart's workload too. During labor, there are sudden changes in blood flow and blood pressure, especially when pushing. After giving birth, stress put on the heart during pregnancy and labor slowly goes down over several weeks.

What are the risks?

The risks depend on the type of heart condition and how serious it is. Some examples are:

  • Heart rhythm issues. These also are called arrythmia. Arrythmia can make the heart feel like it beats too fast, too slow or with an unusual rhythm. Tell your health care team if you have any of these symptoms. Heart rhythm issues can lead to blood clots. And blood clots raise the risk of other heart problems and stroke.
  • Heart valve issues. The heart has four valves that keep blood flowing in the correct direction. Scarring or defects of the heart or its valves can raise the risk of complications during pregnancy. So can having an artificial heart valve. If your valves don't work right, you might have trouble tolerating the increased blood flow that happens during pregnancy.

    Valve problems or artificial valves carry another risk. They can make you more likely to get an infection of the lining of the heart and heart valves. This is called endocarditis. Without treatment, it can be life-threatening.

    Artificial heart valves that are made of strong, long-lasting materials are called mechanical valves. Mechanical valves pose serious risks during pregnancy. If you have a mechanical valve, blood-thinner medicines need to be adjusted by your health care team. And the risk of life-threatening blood clots of the heart valves goes up. Taking blood thinners can put the baby at risk too.

  • Congestive heart failure. With heart failure, the heart doesn't pump blood as well as it should. As blood volume and stress on the heart rise during pregnancy, congestive heart failure can become worse.
  • Congenital heart defect. If you were born with a heart problem, your baby has a greater risk of getting some type of heart defect too. You also might be at risk for heart problems during pregnancy and of premature birth.

Do some heart conditions cause more complications than others do?

Some heart conditions pose life-threatening risks for a pregnant person or the baby. Depending on the circumstances, certain conditions require major treatments before you try to get pregnant. For example, some people need heart surgery before they try to conceive.

Pregnancy isn't recommended for people who have conditions such as:

  • Moderate to severe heart failure, also called class III or class IV heart failure.
  • Ongoing heart muscle weakness that started late in a previous pregnancy or shortly afterward. This is called peripartum cardiomyopathy.
  • Serious narrowing of the mitral or aortic heart valves.
  • An aortic valve with two flaps instead of the usual three, along with an enlarged aorta.
  • A birth defect that causes the body's largest blood vessel to narrow. This is called coarctation of the aorta.
  • A rare heart defect present at birth that affects blood flow in the heart and lungs. This is called Eisenmenger's syndrome.
  • Some cases of a genetic disorder that affects connective tissue in the body, called Marfan syndrome.
  • High blood pressure that affects the arteries in the lungs and the right side of the heart. This is called pulmonary hypertension.

Sometimes, an abortion early in pregnancy is recommended for some people who have certain types of severe heart disease. This is because the risk of death or serious medical problems is very high for the pregnant person.

What about medicine?

Medicine that you take during pregnancy can affect your baby. But the benefits often outweigh the risks. If you need medicine to control your heart condition, your health care team will prescribe the safest medicine. And the amount that you take, called the dose, also will be tailored to your needs.

Use the medicine exactly as prescribed. Don't stop taking it or change the dose on your own.

How should I prepare for pregnancy?

Meet with your health care team before you try to get pregnant. Start by making an appointment with your heart doctor, called a cardiologist. Also make an appointment with the doctor who will handle your pregnancy. You'll likely be referred to a health care professional who takes care of people with very high-risk pregnancies. This doctor is called a maternal-fetal medicine specialist. You also might want to talk with other members of your health care team, such as your family doctor.

Your medical team will check how well you're managing your heart condition. They'll also consider treatment changes you might need before you become pregnant.

Certain medicines that treat heart conditions aren't used during pregnancy. Depending on your situation, your doctor might change your medicine or dosage before you become pregnant. Ask what risks are involved.

If you have a pregnancy that you didn't expect, see your cardiologist and a high-risk-pregnancy doctor as soon as possible.

What can I expect during prenatal visits?

You'll see your health care team often during pregnancy. Your weight and blood pressure will likely be checked at every visit. You might need frequent blood and urine tests too.

How often you see your cardiologist during your pregnancy will depend on how severe your heart condition is. You might need tests to check your heart health, including:

  • Echocardiogram. This is a type of ultrasound that uses sound waves to make images of the heart and the structures inside it.
  • Electrocardiogram. This test records the heart's electrical activity.

How can I make sure my baby is OK?

Your health care team will monitor your baby's health throughout the pregnancy. Routine ultrasound exams can help track your baby's growth. Other types of ultrasounds can be used to find heart conditions. Your baby might need to be closely watched after birth. The baby may need treatment as well.

How can I prevent complications?

Take good care of yourself while you're pregnant. For example:

  • Keep your prenatal appointments. Visit your health care team regularly throughout your pregnancy.
  • Take your medicines as prescribed. Your doctors will prescribe the safest medicine at the dose that's right for you.
  • Get plenty of rest. Take a daily nap if you can. And stay away from strenuous physical activities.
  • Watch your weight gain. Gaining the right amount of weight supports your baby's growth and development. Gaining too much weight places more stress on your heart. Ask your health care team how much weight you should aim to gain.
  • Manage anxiety and stress. Ask questions about your progress. Find out what to expect during labor and delivery. Knowing what's happening can help you feel more at ease. Also, make time for things that relax you. For example, you could try meditation or spend time in nature.
  • Know what's off-limits. Don't smoke, drink alcohol or take illegal drugs. These can harm your baby's health.

    If you tolerated 1 to 2 servings of caffeine a day before you got pregnant, talk to your cardiologist or pregnancy doctor. Ask if it's safe for you to keep drinking this limited amount of caffeine during your pregnancy. You may be told to drink less than 200 milligrams of caffeine a day. That's about the amount in an 8-ounce cup of brewed coffee. Exact amounts of caffeine in coffee or tea vary by brand though. If you notice a fast or unusual heartbeat with caffeine, you may wish to stop drinking it — especially if you have an arrhythmia.

What symptoms should I report to my health care team?

Call your health care team right away if you have any symptoms that concern you. Symptoms of a heart problem can include:

  • Trouble breathing or any shortness of breath.
  • Pounding, fast or unusual heartbeat.
  • Chest or belly pain.
  • A bloody cough or coughing at night.
  • Swelling in the lower body, such as in the legs or feet.
  • Extreme tiredness.
  • A faint, woozy, weak or unsteady feeling.
  • A headache that keeps getting worse.

What about labor and delivery?

Your health care team might advise that you deliver your baby at a medical center that specializes in high-risk pregnancies. In general, pregnant people whose heart conditions are under control can give birth when they go into natural labor. But sometimes, a procedure is done to help a pregnant person go into labor on a set date under controlled conditions. This is called induced labor. You might need this if your care team has certain concerns about your heart or blood flow.

Special equipment might be used to track your health during labor. Your heart rate and rhythm might need to be monitored throughout labor and delivery.

Your contractions and the baby's heart rate are watched closely as well. Instead of lying flat on your back, you might be asked to lie on your side. You might be asked to bring one of your knees toward your chest.

Your health care team might recommend that you receive medicine to keep you from feeling labor pain, called anesthesia. The anesthesia may be given through a thin tube into your spinal column, called an epidural. Or you might receive it as a shot into your spinal column, called a spinal block. If you give birth through your vagina, your health care team might limit your pushing. To do this, they may use tools that gently guide the baby out of the birth canal.

If you're at risk of endocarditis, you might receive antibiotic treatment just before and after delivery.

It's unusual to need a C-section because of a heart condition. If you develop a problem that leads to a C-section, special care is taken to track your heart health during the delivery. Your heart also is monitored for the next day or two afterward. If you have certain forms of severe heart disease, your health care team might suggest setting a date to induce labor.

Will I be able to breastfeed my baby?

Breastfeeding is encouraged for most women who have heart conditions, even many of those who take medicine. Ask your health care team if any treatment changes need to be made before you start breastfeeding.

Some pregnant people were born with a heart problem that greatly raises the risk of endocarditis. If that's the case for you, your doctor will likely talk with you about the risk of an infection while breastfeeding. The infection is called mastitis, and it could pose a special risk for you. That's why pumping and feeding breast milk from a bottle might sometimes be recommended instead of putting the baby to your breast.

Aug. 10, 2023 See more In-depth