Pregnancy is sometimes described as a marathon for the body that maxes out every part, including the heart. The cardiovascular system undergoes major changes to support the growing fetus, and while most people adapt well, about 1 in 7 women experience pregnancy-related cardiovascular complications that require extra care.

“Your heart works harder during pregnancy, and knowing the signs of trouble can help prevent serious complications, such as hypertensive disorders, heart failure, arrhythmias, cardiac arrest, and stroke,” says Dr. Hannah Rosenblum, a cardiologist at NewYork-Presbyterian/Columbia University Irving Medical Center.

Health Matters spoke with Dr. Rosenblum to understand why pregnancy may be a stressor on the heart, which signs and symptoms to look out for, and steps you can take to help reduce risk of complications during and after pregnancy.

How does pregnancy affect the heart?

Both pregnancy and childbirth put stress on the heart and circulatory system. Cardiac output, or the amount of blood the heart pumps per minute, increases by up to 50% during pregnancy. Since your heart has to work harder, both blood volume and heart rate increase in order to meet the metabolic demands of the fetus and placenta. Cardiac output begins to rise in the first trimester, levels off somewhat in the second, and increases again in the third. During active labor — which is like an extremely intense workout — there is even more stress on the heart.

What symptoms are normal, and what may signal a problem?

Mild shortness of breath, a faster heart rate, and some leg swelling are expected symptoms during pregnancy. But you should seek immediate medical attention if you experience any of the following, as they may indicate you are at risk for cardiovascular complications:

• Sudden or severe shortness of breath
• Chest pain or pressure
• Swelling in legs that doesn’t improve overnight
• Fainting or feeling like you might pass out
• Rapid or irregular heartbeat
• Severe headaches or vision changes (these are possible signs of preeclampsia)

In general, I always recommend sharing any and all symptoms with your doctor, even if you don’t think they are serious, just to be on the safe side. If they’re concerned, they may refer you to a cardiologist for further evaluation.

Who is most at risk for heart complications during pregnancy?

People with preexisting conditions like high blood pressure or diabetes, those who are overweight, above the age of 40, and anyone with prior cardiovascular disease face higher risks. Women of African American, American Indian, or Alaska Native background are also at higher risk. These patients often benefit from early consultation with a maternal-fetal medicine specialist and potentially a cardiologist in order to assess their risk.

Can lifestyle changes help reduce risk of your heart health being affected by pregnancy?

Yes, they can. I advise my patients to prepare for pregnancy like they are training for an athletic event. Before you become pregnant, try to adopt these lifestyle habits:

• Aim for at least 150 minutes of moderate-intensity exercise per week
• Follow a nutritious, heart-healthy diet (whole foods, fruits and vegetables, lean proteins, whole grains, and healthy fats) and avoid excess sugar, sodium, and processed foods
• Refrain from smoking and limit alcohol consumption

Is it safe to get pregnant if you have a heart condition?

It depends on the condition — each patient has to be assessed to determine their personal risk of heart failure, arrhythmias, or even fatality. If someone has congenital heart disease, for example, they may have just a slightly increased risk, whereas for someone with severe pulmonary hypertension, pregnancy may be prohibitive. These decisions require an individualized plan with a cardio-obstetrics team.

How should heart health be monitored during and after pregnancy?

For most healthy pregnancies, you should have a routine monthly OB visit, where they will check your blood pressure and heart rate. Higher-risk patients may require at-home monitoring (keeping track of symptoms, taking blood pressure readings, etc.). Postpartum, blood pressure can spike within the first 10 days, so this is critical.

Does pregnancy affect long-term heart health?

For most people, pregnancy usually has no lasting impact on heart health. But if you develop complications like gestational hypertension, preeclampsia, or gestational diabetes, it may increase your future risk for heart failure, stroke, and coronary disease. For these patients, it’s especially crucial that they work with their doctor to create a plan for how they will return to a healthy weight postpartum, control cholesterol and blood pressure, and learn to manage their condition.