Changes to the heart and blood vessels during pregnancy
During pregnancy, changes occur to the heart and blood vessels. These changes put extra stress on a woman’s body and require the heart to work harder. The following changes are normal during pregnancy. They help ensure that your baby will get enough oxygen and nutrients.
- Increase in blood volume. During the first trimester, the amount of blood in the body increases by 40 to 50 percent and remains high.
- Increase in cardiac output. Cardiac output refers to the amount of blood pumped by the heart each minute. During pregnancy, the output increases by 30 to 40 percent because of the increase in blood volume.
- Increase in heart rate. It is normal for the heart rate to increase by 10 to 15 beats per minute during pregnancy.
- Decrease in blood pressure. Blood pressure may decrease by 10 mmHg during pregnancy. This drop can be due to hormone changes and because there is more blood directed toward the uterus. Most of the time, the decrease does not cause symptoms and no treatment is needed. Your healthcare provider will check your blood pressure during your prenatal appointments and will tell you if blood pressure changes are cause for concern.
These changes cause fatigue (feeling overtired), shortness of breath and light-headedness. All of these symptoms are normal, but talk to your healthcare provider if you are concerned or have any questions.
If you have a heart condition you may need to take special precautions before and during pregnancy. Some heart conditions can increase a woman’s risk of complications. In addition, some women have heart or blood vessel conditions that are not identified until pregnancy. The mother’s health and well being are critical because if something bad happens to her, the baby is unlikely to survive.
- Learn about our Cardio-Obstetrics Clinic
Planning pregnancy when you have a heart condition
If you have a heart condition, such as those listed here, you should be evaluated by a cardiologist (a heart specialist) and an obstetrician who specializes in high-risk pregnancy before you start planning a pregnancy.
- Hypertension (high blood pressure) or high cholesterol.
- Prior diagnosis of any type of heart or blood vessel disease, including aorta disease, arrhythmia, heart murmur, cardiomyopathy, heart failure, Marfan syndrome or rheumatic fever.
- Prior cardiac event (transient ischemic attack or stroke).
- Poor functional status, defined as NYHA class III or IV (shortness of breath with very minimal exertion). The New York Heart Association (NYHA) functional status is a set of clinical classifications that rank patients as class I-II-III-IV according to the degree of symptomatic or functional limits or cyanosis (a blue tint to the skin, lips and finger nail beds, indicates the body is not receiving enough oxygen-rich blood). For more information about this, ask your healthcare provider.
- Abnormal heart rhythm (arrhythmia/dysrhythmia).
- Severe narrowing of the mitral or aortic valve or aortic outflow tract (diagnosed using echocardiography).
- Ejection fraction less than 40%. Ejection fraction is the amount of blood pumped out of the left ventricle during each heartbeat. Your ejection fraction indicates how well your heart is pumping. A normal ejection fraction ranges from 50% to 70%.
The cardiologist will review your health history, perform a physical exam and order diagnostic tests to check your heart function and the severity and extent of your condition. After reviewing the test results, the cardiologist will talk to you about how safe it is for you to be pregnant and the risk of complications during pregnancy, including potential short- and long-term risks to you and the baby. The cardiologist can tell you about any medications or other treatments you may be need before pregnancy.
Be sure to discuss all of your medications (including heart medications and any over-the-counter medications you take routinely) with your doctor so your medication dosages can be changed if needed. You may also need to change medications to take those that are safer to take during pregnancy.
By preparing for pregnancy and following up regularly with your cardiologist during pregnancy, most women with a heart condition can safely become pregnant and have a healthy baby.
Pre-existing cardiovascular conditions and pregnancy
Congenital heart conditions and pregnancy
Congenital heart defects are the most common heart problems that affect women of childbearing age. These include shunt lesions, obstructive lesions, complex lesions and cyanotic heart disease.
Shunt lesions are the simplest and most common congenital heart defects. Shunts include atrial septal defect (ASD), which is a hole between the upper chambers of the heart; ventricular septal defect (VSD), which is a hole between the lower chambers of the heart; and patent ductus arteriosus (PDA), which means there is abnormal blood flow between the aorta and pulmonary artery. If the hole is large, a fair amount of blood from the left side of the heart will flow back into the right side of the heart. The blood gets pumped back to the lungs again and causes strain on the heart. This can lead to an enlarged heart, abnormal heart rhythms and increased pressure in the lungs (pulmonary hypertension). Pulmonary hypertension, when severe, can cause the blood flow across the shunt to move in reverse. This can cause low levels of oxygen in the blood (cyanosis). In such cases, pregnancy is not recommended due to the high risk of the mother dying.
Obstructive lesions reduce the amount of blood flow to the heart and the body’s major blood vessels. One such lesion, aortic coarctation is a narrowing in the descending aorta, which is the largest artery in the body. Aortic coarctation can cause a pregnant woman to have high blood pressure. The condition can also keep the placenta (the collection of blood vessels that supplies the baby with blood) from getting enough blood. Depending on how severe the narrowing is, you may need a procedure before or during pregnancy to keep you and the baby safe during pregnancy.
Complex lesions include transposition of the great arteries. This means the aorta and pulmonary arteries are attached to the wrong ventricles (bottom chambers of the heart). Surgery to repair the problem can cause problems with the heart chambers, especially if the right ventricle pumps blood out to the body (this is usually the job of the left ventricle). In this case, the problem can cause heart failure and leaky heart valves, and the conditions can become worse during pregnancy. If you have this condition, you will need to be closely followed during pregnancy.
Cyanotic heart disease includes tetralogy of Fallot. This is a condition that includes a VSD, narrowing of the pulmonary valve and abnormal configuration of the aorta. Treatment usually keeps cyanosis from recurring. However, the repair can cause a leaky pulmonary valve, and that problem can lead to heart failure and heart rhythm disturbances. If you have a leaky pulmonary valve, you may need to have it corrected before you become pregnant.
In general, most women with congenital heart defects, especially those who have had corrective surgeries, can safely become pregnant. However, the outcome of the pregnancy and risk of complications depends on the type of heart defect you have, how severe your symptoms are, and whether you have heart muscle dysfunction, heart rhythm disturbances or pulmonary hypertension with related lung disease. Your pregnancy can also be affected if you have had particular types of heart surgery.
Valve disease and pregnancy
Aortic valve stenosis means the aortic valve (the valve between the left ventricle and the aorta) is narrowed or stiff. If the narrowing is severe, the heart has to work harder to pump the increased blood volume out of the narrowed valve. This, in turn, can cause the left ventricle (the major pumping chamber of the heart to enlarge – a condition called hypertrophy). Over time, symptoms of heart failure can occur or become worse and increase the risk of long-term complications for the mother.
One common cause of aortic valve stenosis is bicuspid aortic valve disease. This is a congenital heart condition in which there are only two leaflets (also called cusps), instead of the normal three leaflets inside the valve. The leaflets open and close to keep blood flowing in the right direction and prevent backflow. Without the third leaflet, the valve can become narrowed or stiff.
Women with bicuspid aortic valve disease or any type of aortic valve stenosis need to be evaluated by a cardiologist before planning a pregnancy. In some cases, surgery is recommended to correct the valve before pregnancy.
Mitral valve stenosis means the mitral valve (the valve between the left atrium and left ventricle) is narrowed. This condition is often caused by rheumatic fever.
The increased blood volume and increased heart rate that occur during pregnancy can make symptoms of mitral stenosis get worse. The left atrium can become bigger and cause a rapid, irregular heart rhythm called atrial fibrillation. In addition, the problem can cause heart failure symptoms (shortness of breath, irregular heart beat, fatigue and swelling/edema). This can increase the risk to the mother. If you have mitral valve stenosis, you may need to take medications while you are pregnant. Your doctor may also recommend an catheter-based procedure, called percutaneous valvuloplasty, to correct the narrowed valve while you are pregnant. It is important to have mitral stenosis evaluated before you become pregnant. In some cases, surgery or valvuloplasty to correct the valve will be recommended before pregnancy.
Mitral valve prolapse is a common condition that usually doesn’t cause symptoms or require treatment. Most patients with mitral valve prolapse tolerate pregnancy well. If the prolapse causes a severe leak, you may need treatment before you become pregnant. Be sure to talk to your doctor if you plan to become pregnant and follow any recommendations.
Pregnancy in women with prosthetic (artificial) valves
Women who have artificial heart valves may experience complications during pregnancy because:
- Women who have an artificial heart valve need to take lifelong anticoagulant medication, and certain anticoagulant medications can be harmful to the baby. There is controversy about which anticoagulant medication regimen is best during pregnancy.*
- During pregnancy, there is an increased risk of blood clots.
*Use of warfarin, heparin, aspirin, and combinations of these anticoagulant medications have been suggested and compared. The most recent recommendations from the European Heart Association are to use heparin during the first trimester, followed by warfarin up to the 36th week of pregnancy, and subsequent replacement with heparin until delivery OR to use oral anticoagulation medication throughout pregnancy, until the 36th week, followed by heparin until delivery.
The use of warfarin is less harmful if the dose is kept to less than 5 mg. In addition, other specialists have recommended the addition of low-dose aspirin to treat women who are at high risk.
If you have a prosthetic valve and are taking an anticoagulant medication, it is very important to be evaluated by a cardiologist before planning a pregnancy. The cardiologist will talk to you about your potential risks and determine the best anticoagulant therapy routine for you.
In addition, ask your doctor what precautions you should continue to follow to prevent endocarditis.
Aorta Disease and pregnancy
Pressure in the aorta increases during pregnancy and when bearing down during labor and delivery. This extra pressure increases the risk of an aortic dissection or rupture, which can be life-threatening.
It is very important for women who have aorta disease to be evaluated by a cardiologist before planning a pregnancy. A thorough evaluation of your condition will provide the physician with information about the potential risks of pregnancy. It is also important to note that some conditions, such as Marfan syndrome, are genetic and can be passed down to children, so genetic counseling may be recommended.
After you become pregnant
Congratulations on your pregnancy! During pregnancy, it’s important to:
- Continue following a heart-healthy diet.
- Exercise regularly, as recommended by your cardiologist.
- Quit smoking!
In addition to keeping your follow-up appointments with your obstetric provider throughout pregnancy, schedule regular follow-up visits with your cardiologist and follow the recommendations carefully. Your cardiologist can evaluate your heart condition throughout your pregnancy so symptoms and/or potential complications can be detected and treated early. This will help ensure a safe outcome for you and your baby.
Some conditions may require a team approach that involves you and your obstetrician, cardiologist, anesthesiologist and pediatrician. Depending on your heart condition, special arrangements may be needed for labor and delivery.
Cardiovascular disorders that may develop during pregnancy
Peripartum cardiomyopathy is a rare condition. It is when heart failure develops in the last month of pregnancy or within five months after delivery. The cause of peripartum cardiomyopathy remains unknown. Certain patients, including those with multiple pregnancies and those of African descent, are at greatest risk. Women with peripartum cardiomyopathy have symptoms of heart failure. After pregnancy, the heart usually returns to its normal size and function. But, some women continue to have poor left ventricular function and symptoms. Women with peripartum cardiomyopathy have an increased risk of complications during future pregnancies, especially if the heart dysfunction continues.
Hypertension (high blood pressure)
About 6% to 8% of women develop high blood pressure, also called hypertension, during pregnancy. This is called pregnancy-induced hypertension (PIH) and is related to preeclampsia, toxemia, or toxemia of pregnancy. Symptoms of PIH include high blood pressure, swelling due to fluid retention, and protein in the urine. Pregnancy-induced hypertension can be harmful to the mother and the baby. To learn more about who is at risk for PIH, symptoms of PIH, and how PIH is diagnosed and treated, click on the following links:
- Cleveland Clinic - Pregnancy-Induced Hypertension
- Cleveland Clinic - Preeclampsia and Eclampsia
- American Heart Association - Pregnancy and High Blood Pressure
Heart attack (myocardial infarction) is fortunately a very rare but potentially deadly complication that can occur during pregnancy or during the first few weeks afterwards. A heart attack can be caused by many things. Patients with coronary artery disease (“hardening of the arteries”) can have a myocardial infarction if the plaque inside their arteries ruptures. This problem is becoming more common, since many women wait until later in life to become pregnant. Other causes of a heart attack include a spontaneous blood clot inside a coronary vessel (because pregnancy increases the risk of blood clots) and coronary dissection (a weakening of the vessel wall that leads to a spontaneous tear and clotting). If you have a heart attack, it is critical to get emergency help. Treatment will be focused on ensuring your survival.
Sometimes, the increase in blood volume during pregnancy can cause a heart murmur (an abnormal “swishing” sound). In most cases, the murmur is harmless. But in rare cases, it could mean there’s a problem with a heart valve. Your doctor can evaluate your condition and determine the cause of the murmur.
Arrhythmias and pregnancy
Abnormal heartbeats (arrhythmias) during pregnancy are common. Women who have never had an arrhythmia or heart problem may first develop an arrhythmia during pregnancy. When an arrhythmia develops during pregnancy, it can be a sign of a heart condition you didn’t know you had. Most of the time, the arrhythmia causes little in the way of symptoms and does not require treatment. If you have symptoms, your doctor may order tests to determine the type arrhythmia you have and attempt to determine its cause.