What is pre-existing heart disease in pregnancy?

Pre-existing heart disease is a heart problem that you had before you got pregnant. This often means a heart condition that you were born with (congenital). But it may also include things that you developed later in life. These can include heart problems that may have been fixed.

Common congenital heart conditions that may be affected by pregnancy include:

• Mitral stenosis

• Atrial septal defect

• Ventricular septal defect

• Patent ductus arteriosus

• Aortic stenosis

• Mitral valve prolapse

• Tetralogy of Fallot

• Coarctation of the aorta

• Transposition of the great arteries

Other pre-existing conditions that may affect your pregnancy include:

• Heart rhythm disorders

• High blood pressure

• Heart failure

• Aortic aneurysm

• Marfan syndrome

What causes pre-existing heart disease in pregnancy?

Most heart problems you’re born with happen by chance. No one knows what causes them. A heart valve problem may come on after an infection or other health condition. Rheumatic fever caused by strep throat is a common source of infection that affects heart valves.

Even if your heart disease doesn’t cause symptoms or hasn’t affected your life, it can cause issues during pregnancy. This is because of changes in your body that happen when you’re pregnant. Some people don't know they have pre-existing heart disease until the stresses of pregnancy reveal the problem.

Starting in your first trimester, your blood volume rises by about half. The extra fluid makes your heart work harder. Your heart responds by increasing its cardiac output. This is the amount of blood that your body pumps through your circulatory system. Your blood pressure decreases to allow the extra blood volume to flow. But some people develop high blood pressure instead. This can put more stress on your heart, especially if you have a pre-existing heart condition.

Changes in your heart and vascular system can also happen during labor and delivery. Large amounts of blood move from your uterus into your circulation, as your uterus contracts. This causes changes in your blood pressure, heart rate, and cardiac output. If you get an epidural or spinal anesthesia, this can also cause your blood pressure to decrease.  

After childbirth, your cardiac output increases and your heart rate slows down. You can have heavy blood loss with delivery. This can change your heart rate, blood pressure, and cardiac output.

What are the symptoms of pre-existing heart disease in pregnancy?

Most people with a pre-existing heart issue have been diagnosed and treated before pregnancy. Some people with minor heart problems may not know that they have a heart issue. These people, and those with repaired heart conditions, may develop symptoms during pregnancy.

The following are common symptoms of heart disease. Symptoms can occur a bit differently in each pregnancy. They may include:

• Trouble breathing, especially at night or when you’re not active

• Shortness of breath with exertion

• Not being able to do normal activities, because of weakness or severe tiredness (fatigue)

• Lightheadedness or fainting

• Irregular heart rate (palpitations)

• Blue skin coloring because of low levels of oxygen in your blood (cyanosis)

The symptoms of heart disease may look like symptoms of other health problems. Always see your healthcare provider for a diagnosis.

How is pre-existing heart disease diagnosed in pregnancy?

Diagnosing a heart issue in pregnancy can be tricky. This is because some of the normal symptoms of pregnancy look like symptoms of heart disease.

Your healthcare provider will ask about your health history. They will also give you an exam. You may also need the following tests:

• Electrocardiogram (ECG). This test notes the electrical activity of your heart. It also shows abnormal heart rhythms and helps find heart muscle damage.

• Echocardiography. This test looks at the structure and function of your heart. It uses sound waves recorded on an electronic sensor. These show a moving picture of your heart and heart valves.

• Right heart catheterization. For this test, a pressure monitor is put into the chambers of the heart. The monitor is put into a large vein in your neck or the groin and moved to your heart. Understanding how high or low the pressures in the heart are can help your healthcare team diagnose a problem. This can also help them come up with treatment choices that are best for you. This is rarely done in pregnancy as it typically needs a sedative as well as contrast dye.

• Cardiac MRI. This test uses electromagnetic waves to create images of the heart and its surrounding structures. No ionizing radiation is used in this test. Contrast is generally not given to pregnant people. But it may be used if the heart condition is serious enough.

How is pre-existing heart disease treated in pregnancy?

Treatment will depend on your symptoms, pregnancy, and general health. It will also depend on how severe the condition is.

Your healthcare provider will look at the risk that your heart disease may have on your pregnancy. You may need to see a high-risk obstetrician. You may also need to see a heart doctor (cardiologist) who specializes in congenital heart disease or high-risk prenatal care.

You may need to see your healthcare provider more often. This is so they can watch you and your baby. You may also need medicine to help your heart work better.

Your healthcare team will decide the safest way for you to have your baby. You may give birth vaginally. Or you may need to have a cesarean section. During labor, you may need to have your heart checked continuously.

What are possible complications of pregnancy and pre-existing heart disease?

Normal changes in pregnancy may cause problems if you have heart disease. Your healthcare provider will watch you closely to make sure you and your baby stay healthy.

If you have a congenital heart defect, there’s a chance your baby will also have a heart issue. It may not be the same heart problem you have. You’ll likely need high-risk prenatal monitoring.

Living with pre-existing heart disease in pregnancy

A congenital heart condition is a lifelong condition. Most of the time, your heart defect is fixed in childhood. Other times, you may not have symptoms for many years.

But pregnancy causes changes that can cause problems for women with heart disease. Before you get pregnant, you should think about preconception counseling. A specialist with experience in pregnancy and heart disease can help you make choices about pregnancy. They can also help you learn how to maintain or improve your health for the best possible pregnancy outcomes.

Ask your healthcare team which heart medicines you take are safe to use during pregnancy. Some medicines can cause birth defects and should not be used. Don't stop taking your medicines without talking with your provider first. 

When should I call my healthcare provider?

Call your healthcare provider if your heart symptoms get worse. You should also call them if you have any new symptoms.

Key points about pregnancy and pre-existing heart disease

• Pre-existing heart disease is a heart problem that you had before you got pregnant.

• Even if your heart disease doesn’t cause symptoms or hasn’t affected your life before pregnancy, it can cause issues during pregnancy. This is because of changes in your body that happen when you’re pregnant.

• Before you get pregnant, you should think about preconception counseling. A specialist with experience in pregnancy and heart disease can help you.

• You may need to see a high-risk obstetrician. You may also need to see a heart doctor (cardiologist) who specializes in congenital heart disease.

• Your healthcare provider will watch you closely to make sure you and your baby stay healthy.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions, especially after office hours or on weekends.