Pregnancy stresses your heart and circulatory system. During pregnancy, your blood volume increases by 30% to 50% to nourish your growing baby. This makes your heart pump 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 will take several weeks after delivery for the stresses on the heart to return to the levels they were before you became pregnant.
Understanding the risks
The risks of pregnancy 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 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 of heart valves. Taking blood thinners also can 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 also may be at risk for heart problems occurring during pregnancy and of premature birth.
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, called pulmonary hypertension.
Preparing for pregnancy
Before you try to conceive, schedule an appointment with your cardiologist and the health care professional who'll be handling your pregnancy. You'll likely be referred to an obstetrician who specializes in very high-risk pregnancies. You also might want to check in with other members of your health care team, such as your family clinician.
Your medical team will evaluate how well you're managing your heart condition and consider treatment changes you may need before you become pregnant.
Certain medications used to treat heart conditions aren't used during pregnancy. Depending on the circumstances, your health care professional may adjust the dosage or make a substitution and explain the risks involved.
Taking good care of yourself is the best way to take care of your baby. For example:
Keep your prenatal appointments. Visit your health care professional regularly throughout your pregnancy.
Take your medication as prescribed. Your health care professional will prescribe the safest medication at the most appropriate dose.
Get plenty of rest. Take a daily nap, if you can, and avoid strenuous physical activities.
Monitor your weight gain. Gaining the right amount of weight supports your baby's growth and development. Gaining too much weight places additional stress on your heart.
Manage anxiety. 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.
Know what's off-limits. Avoid smoking, alcohol, caffeine and illegal drugs.