Pregnancy and heart disease

Pregnancy increases the workload on the heart. There is also a link between some pregnancy-related conditions and possible heart disease in later life. Learn more about pregnancy and the heart and find out how you can keep your heart healthy and reduce your risk.

How does pregnancy affect your heart?

Your heart has to work much harder than usual during pregnancy as it has a much greater volume of blood to pump around your body. In most women, it is usually close to 45% more. 

Going through labour and giving birth also places additional strain on the heart. 

During labour, especially during the pushing stage, there are sudden fluctuations in blood flow and pressure.  

It usually takes a couple of weeks for the heart to recover and return to its pre-pregnancy levels. 

High blood pressure and pregnancy

There are a number of high blood pressure disorders that can affect women in pregnancy. The clinical term for these conditions is hypertensive disorders in pregnancy (HDP). They include: 

• pre-existing hypertension  
• gestational hypertension 
• pre-eclampsia. 

HDP affects up to 10% of all pregnancies in New Zealand.  

Women diagnosed with HDP once are more likely to have it in future pregnancies. They are also at higher risk of high blood pressure and heart disease in later life. 

Pre-existing hypertension

If you’ve been diagnosed with high blood pressure, it’s a good idea to talk to your doctor before getting pregnant or as soon as you know you’re pregnant.

They will review your blood pressure medication and decide how often you need to have your blood pressure checked. They will also talk to you about any lifestyle changes that you can make.

Gestational hypertension

Gestational hypertension is when a woman with normal blood pressure develops high blood pressure during pregnancy. Blood pressure returns to the normal range within three months of the birth.

If you’re diagnosed with gestational hypertension, your doctor may recommend some blood pressure medication. You will also be monitored regularly to make sure you and the baby remain healthy and to check for pre-eclampsia.

Gestational hypertension may also increase your risk of heart disease in future, but more research is required around the long-term effects.

Pre-eclampsia

Pre-eclampsia is a serious condition that occurs when you’re 20 weeks or more pregnant. It affects 3–8% of pregnancies in New Zealand. 

It can occur in women who:  

• have existing high blood pressure before pregnancy 
• or develop high blood pressure during pregnancy (gestational hypertension). 

The risk of developing pre-eclampsia increases if you have had it previously, have a family history of pre-eclampsia, or have insulin-dependent diabetes before becoming pregnant. 

As well as high blood pressure, one or more of your organs may be affected by pre-eclampsia. This is most likely to be your: 

• kidneys  
• liver 
• and/or brain.  

Pre-eclampsia affects the arteries carrying blood to the placenta. This can lead to slow growth and as a result the baby is usually smaller than expected. Your blood clotting system can also be affected.  

If you’re diagnosed with pre-eclampsia, your doctor will give you blood pressure lowering medication and you’ll be closely monitored. On rare occasions some people will need to stay in hospital. Pre-eclampsia usually settles within the first 12 weeks after birth, but it can increase your risk of heart disease in later life.  

Read more about pre-eclampsia.

Pre-eclampsia and heart disease

If you’ve had pre-eclampsia or high blood pressure during pregnancy, you are at greater risk of heart attack and stroke in later life.

While you might not be able to prevent pre-eclampsia, you can reduce your overall risk of later heart disease by staying active and eating a heart-healthy diet.

Reduce your risk of heart disease

Gestational diabetes and heart disease

Gestational diabetes is a type of diabetes which occurs during pregnancy. Often there are no signs or symptoms, but you should be screened for it during your pregnancy. 

Having gestational diabetes means you are at higher risk of heart disease and type 2 diabetes in later life. 

Gestational diabetes affects around 6% of all pregnancies. Māori, Pasifika and South Asian women are more at risk than New Zealand Europeans. 

For some women, gestational diabetes will go within three months of birth, but you will need a test 12 weeks after birth and then annual testing after that. However, a woman who has gestational diabetes has an increased risk of developing type 2 diabetes in the future and should be tested for type 2 diabetes annually. 

Find out more about gestational diabetes.

Peripartum cardiomyopathy

Peripartum cardiomyopathy, also called postpartum cardiomyopathy, is a rare heart condition that affects women late in pregnancy or in the first few weeks or months after birth. It means the heart muscle can’t pump blood as well as it should around the body.

For the vast majority of women affected by peripartum cardiomyopathy, the heart muscle function recovers post pregnancy.

Read more about cardiomyopathy

Can I get pregnant if I have heart disease or a heart condition?

If you already have a heart condition, you may need special care during pregnancy because of the workload that pregnancy places on the heart.

It’s best to talk to you doctor before you get pregnant. If you’re already pregnant, talk to your doctor as soon as possible.

Depending on your condition and any heart medication you may need to take special precautions. Your doctor is the best person to advise what’s best for the health of you and your baby.

The large majority of women with heart conditions can still get pregnant and give birth safely without long-term negative effects on their health.

There are some conditions where women should be careful before planning a pregnancy.

Stories about pregnancy and heart conditions