Pregnancy care for women with cardiomyopathy

By Dr Fiona Walker - Head of the maternal cardiology programme at University College London Hospitals (UCLH)

Pregnancy is an issue for women with heart problems. In the past many women with conditions such as cardiomyopathy might have been told it is not safe for them to have babies. But we now know that many such women can have their babies safely if they receive high-quality specialist care.

This article covers:

  • pregnancy risk and how I assess it
  • the circulatory changes that occur in pregnancy and how they impact on the heart
  • the impact of underlying heart disease and how its impacts on pregnancy, immediately and long term
    outcomes for mother and baby


There is a risk associated with pregnancy even for mothers with a normal heart and around 1 in 10,000 will die in pregnancy.

The American College of Obstetricians have quantified risk with regards to an adverse event in pregnancy (death and disability). They say minimal risk is less than one per cent, moderate risk is five to 15 per cent, and high risk is 25 to 50 per cent.

Personally I think a high risk is five per cent (1 in 20) when you consider the chance of a woman with a normal heart having a risk of 1 in 10,000.

It is important to consider what we mean by risk. A hazard is an event that can lead to harm and risk is the chance of that harm occurring and its magnitude.

Many cardiac societies have produced guidelines for doctors. They attempt to make everything as simple as possible so that there is a classification of conditions and their risk, from no risk (WHO grade one), to very high risk (three), and conditions where pregnancy is inadvisable (four).

So where do cardiomyopathies fit into this grading? Dilated and hypertrophic cardiomyopathy are considered WHO class grade two to three. In other words, a small increased risk or significantly at risk. So there is quite a wide spectrum of risk with these conditions. So again these tables are not particularly helpful.

If you have significant impairment of ventricular function, pregnancy is significantly high risk. This would be pump function estimated at less than 30 per cent compared to a normal of 60 to 70 per cent.

Risk means different things to different people. And it’s constructed from our own experiences and perceptions. There are three types of risk:

  • scientific – you look at data and outcomes in the medical literature
  • perceived – perceptions from your own experiences in life
  • virtual – own convictions and beliefs no matter what happens, based on personality

The medical literature for pregnancy is not scientifically robust. It tends to be retrospective, so doctors are looking backwards at what happened to women. It also tends to use many centres to have sufficient numbers. However, if you research in this way you can have many doctors providing information and they may all look after patients differently. So what we are left with in pregnancy medicine is often our own judgement based on experience and our own convictions and beliefs.

So when considering risk, there’s not just you as a patient, there’s my input as a doctor. I’m the sole consultant responsible for the pregnancy service at University College London Hospitals where 80 to 90 pregnant women with complex heart diseases are being looked after at any one time. I’ve been a consultant for ten years and looked after over 750 pregnancies to date with excellent outcomes.

When I discuss risk during a pre-pregnancy consultation, I try to be non-directive. I’m not particularly paternalistic but I will try to inform people of what is known and the best available data. I’ll also try to include what I think isn’t known and the limitations of the data and then I try to give my best judgement about risk and outcome. We then agree a care plan. From my perspective it’s all about you, the patient, being empowered to make an informed choice about whether you go ahead with pregnancy as you do for making any other major life choices.

The cardiac changes in pregnancy

During pregnancy the heart has to work a lot harder. The output from the heart doubles and heart rate goes up by 15 per cent. The physiological changes have been likened to running a marathon; the difference, of course, is that you are doing it for nine months.

For anyone with a heart problem, this extra work is superimposed on a structural heart abnormality.
The blood pressure falls during pregnancy and there is an increased tendency to push fluid into the lungs, called pulmonary oedema. (That’s even in women with a normal heart).

All of these changes don’t just disappear the minute the baby is born. It can take up to 12 weeks for the changes to resolve completely. Often in high-risk conditions, monitoring will have to continue many weeks afterwards.

Pre-pregnancy planning

Minimising pregnancy risk is all about pre-pregnancy planning. Complications can be reduced and prevented by a pre-pregnancy assessment. We aim to see patients before they become pregnant to try to assess risk and make a judgement about outcome and then provide safe, multi-disciplinary team care.

I have to understand the underlying heart problem and how pregnancy will impact on it. How will the increased volume affect the heart? Are arrhythmias going to get worse and does it matter? What will the impact of pregnancy be on heart valve function? Will there be any late and long-term consequences of pregnancy?

Most women are examined and I look at all the available information including echo, MRI and exercise data. I review all medications to see which ones are safe or unsafe in pregnancy.
I now see more women with devices like pacemakers and defibrillators. I have to think about the other risks involved in pregnancy – the usual risks for any woman having a baby. You have a bigger chance of getting clots, usually in the lungs and in the legs. It’s ten times more common in the pregnant state.

Anyone who has had a previous clot has a further increased clotting risk. If you have obesity, you’re older, have a family history of clotting or an inherited clotting disorder, your risk of clotting in pregnancy is also increased.

I try to make a judgement about risk and try to predict outcomes for mother and baby.
It’s not always easy because I can’t predict if a woman will have twins or develop pre-eclampsia (a pregnancy blood pressure condition). I can’t predict if she will bleed or not bleed at delivery or if there are any other obstetric conditions that may increase risk. That’s why this area of medicine is a speciality that needs a multi-disciplinary team of doctors involving many specialists.
Sometimes if there is a locally engaged cardiologist, you may be able to have shared care – local and at a specialist centre. Often I will see someone once but, if I can find a suitable local cardiologist, I will try to co-ordinate shared care. At the moment there is not enough experience in peripheral centres but it will get better as more people understand the specialty.

Mothers take priority

Maternal health is the priority in all types of heart disease. If you have a sick mother you will have a sick baby. If you have a sick mother, you may have a motherless child.

So in our service, it’s the mother’s health that is the priority. So one of the major discussions we have at the outset is that the potential mother must accept that pregnancy will be terminated or interrupted, and that is irrespective of the gestational age of the infant, if she becomes severely unwell.

We would intervene if the well-being of the mother is declining and she is failing to respond to treatment. We would also want to deliver the baby if we see any downward change in the mother’s ventricular function and if we have arrhythmias that we cannot control with medical therapy.

Types of cardiomyopathy

Pregnancy in women with hypertrophic cardiomyopathy (HCM)

Pregnancy in women with dilated cardiomyopathy (DCM)

Pregnancy in women with arrhythmogenic right ventricular cardiomyopathy (ARVC)


Pregnancy is not without some risk but outcome in the main is good.  You will get varying information depending where you go. As a general rule cardiologists are not normally that comfortable with pregnant women so you have to find one that is!  Do seek a pre-pregnancy review by an expert. You should only go to someone who understands pregnancy and your heart condition. There are now specialist centres around the UK and that’s where you need to go to get sensible advice.  If you want to know who and where the expert doctors are Cardiomyopathy UK can let you know.

For women, just as in normal life, there’s an awful lot to think about and this is just another life decision.

Working in the pregnancy part of our cardiology service I realise that acceptable risk is in the eye of the beholder and my role is to minimise that risk and ensure that patients are well informed so that they are making an informed choice.

Our experience is now with over 750 pregnancies and 95 per cent of them had no complications at all.  The complications that we did have – heart failure and arrhythmias – were mostly predicted.  Of the two deaths, one was a cardiac death which was a patient with congenital heart disease and a connective tissue disorder. She was well aware of the risk but her death was unexpected.  The other death was due to the pregnancy not the heart.

How to access our service

I get referrals from all over the place.  Nowadays doctors are more reluctant to refer you for second or third opinions. But if you feel strongly ask your GP to refer you direct. Any hospital doctor can also refer you to our service.