Woman on a couch holding her pregnant belly


Pregnancy and heart health

Pregnancy can increase the amount of stress put on the body, including the heart and cardiovascular system. This is why pregnancy is often referred to as ‘nature’s stress test.’

During pregnancy, the body experiences an increase in blood volume, heart rate, and cardiac output – that is the amount of blood pumped per minute.

These changes mean the heart must work harder to move blood around the body, which can increase the risk of heart conditions in both healthy people and those with preexisting cardiovascular diseases.

In fact, even though maternal death rates in Australia are very low, the most frequent cause of maternal deaths between 2011 and 2020 was cardiovascular disease.

Heart health risks and conditions that can occur during pregnancy

Heart risks to be aware of throughout pregnancy

Heart valve disorders

A heart valve disorder is when one or more of the valves of the heart doesn’t work properly, affecting the flow of blood through the heart. Issues with heart valves may include valves not closing or opening properly, being too stiff or thick, or not being formed properly. Heart valve disorders can range from mild to severe. During pregnancy, people with heart valve disorders may face a greater risk of complications due to the increased blood flow across already diseased valves. Heart valve disorders that carry an increased risk during pregnancy can affect any of the four heart valves, but in particular the mitral and aortic valves.

People with mechanical (‘metal’) heart valves face special challenges in pregnancy, including an increased risk of blood clots. People with mechanical heart valves are typically required to take anticoagulants (‘blood thinners’) throughout their life. However, some of these medications can put the developing baby at risk, which means treatment may need to be modified during pregnancy.

Heart health concerns during the first trimester (conception to 12 weeks)

Congenital heart defects in the baby

Congenital heart defects, also known as congenital heart disease (CHD), are structural abnormalities of the heart, aorta, or other large blood vessels which are present at birth.

These defects range from simple to complex and may include holes in the heart, obstructed blood flow, abnormal blood vessels or heart valves, an underdeveloped heart, or a combination of these defects.

A baby’s heart starts developing from conception and all the major parts of the heart are present at eight weeks. During this period, defects can develop. In the majority of cases, the cause of the defect is unknown.

People with existing congenital heart defects may also be at risk of passing the genes that cause these defects onto their baby.

Congenital heart defects may be identified during pregnancy via a fetal echocardiogram, which can evaluate the baby’s heart before birth and is able to provide a more comprehensive image of the heart than a regular pregnancy ultrasound.

However, some heart defects may only be identified after birth or later in life.


During pregnancy, the body goes into a state of hypercoagulability. This refers to the increased risk of developing blood clots (thrombosis).

Hypercoagulability can begin from conception and can continue until the fourth trimester (postpartum).

It is believed that hypercoagulability occurs during pregnancy as a way for the body to protect itself from excessive postpartum bleeding or bleeding during miscarriage.

Pregnancy and hypercoagulability can increase the risk of venous thromboembolism (VTE), which includes pulmonary embolism (PE) and deep venous thrombosis (DVT). Women are up to five times more likely to develop VTE when pregnant or post birth.

Heart health concerns during the second trimester (13 to 26 weeks)

Gestational hypertension, preeclampsia, and eclampsia

Gestational hypertension, also known as pregnancy-induced hypertension, is high blood pressure (greater than or equal to 140/90mmHg) in the latter half of the pregnancy (after 20 weeks) in a person who previously had normal blood pressure.

Gestational hypertension can lead to preeclampsia, a condition where high blood pressure is coupled with protein in the urine and excessive swelling in areas such as the face, hands, and feet.

Preeclampsia is the most common serious condition associated with pregnancy, though individuals with preeclampsia may feel fine, which is why regular check-ups during pregnancy are vital.

Those with severe preeclampsia are also at risk of developing eclampsia - which causes seizures in a person with preeclampsia.

Preeclampsia generally resolves after giving birth.

Heart health concerns during the third trimester (27 to 40 weeks)


Arrhythmias (abnormal heart rhythms) are common in pregnant people and may occur for the first time in pregnancy or may be a reoccurrence of a previous arrythmia.

Arrhythmias, such as atrial fibrillation (AFib), are most often diagnosed in the third trimester.

Treatment will depend on the type of arrhythmia and is often similar to treatment for non-pregnant patients e.g. medication, treatment of underlying conditions etc.

Heart health concerns during the fourth trimester (birth to 12 weeks postpartum)

Even after birth, the body is still undergoing increased stress that can place a woman’s heart health at risk.

In Australia, nearly half of all maternal deaths occur after a woman has given birth.


Spontaneous coronary artery dissection (SCAD) is a rare but serious condition that results when an inner layer of one of the blood vessels in the heart tears. Blood seeps between the artery layers, forms a blockage and can slow or block blood flow to the heart, causing angina, heart attack, abnormalities in heart rhythm or sudden death.

SCAD mostly occurs in women under the age of 50 who have no known risk factors for heart disease.

P-SCAD, refers to SCAD that occurs during pregnancy or up to 12 weeks postpartum, particularly in the first month post-partum. Pregnancy has been found to increase SCAD risk as well as its severity.

P-SCAD represents approximately 5–17% of all SCAD cases with an incidence of 1.81 per 100,000 pregnancies. In addition, pregnant women with P-SCAD tend to be older when having their first child.

Limited research has been done into SCAD, with the Institute leading Australia's first research program to uncover its causes and potential treatments.

Peripartum cardiomyopathy

Peripartum cardiomyopathy (PPCM – occurring around the time of birth), and also postpartum cardiomyopathy (occurring soon after birth), are similar to dilated cardiomyopathy (DCM) in that they cause weakening and enlargement of the heart muscle, which affects the ability of the heart to pump blood around the body.

PPCM most commonly occurs in the last month of pregnancy and in the five months post-birth. It can cause fatigue, low blood pressure, and swelling in the legs and abdomen.

PPCM is treated in specialist centres, and treatment may include differing combinations of medications; reduced fluid and salt intake; and other special interventions.

PPCM is a serious condition, but the majority of people will return to normal heart function within six months of treatment.

People who experience PPCM are also at higher risk of PPCM during future pregnancies.

How to keep your heart healthy during pregnancy

Ways to reduce the risk of heart issues during pregnancy may include:

Read these incredible stories of female patients

True stories of of women who suffered heart disease shortly after giving birth.

Acknowledgement of Country

The Victor Chang Cardiac Research Institute acknowledges Traditional Owners of Country throughout Australia and recognises the continuing connection to lands, waters and communities. We pay our respect to Aboriginal and Torres Strait Islander cultures; and to Elders past and present.

Victor Chang Cardiac Research Institute - The Home of Heart Research for 30 Years