Pregnancy in women with cardiomyopathy

by Dr Maite Tome, consultant cardiologist, the Heart Hospital, London

Pregnancy is a life changing experience for most women. It requires important life, health, emotional and financial adjustments.

The hearts of women affected by cardiomyopathy also face an important challenge.  But most cardiomyopathy patients who become pregnant face no more complications nor major difficulties than others without heart problems. However, when possible, it is advised that a woman with cardiomyopathy who wants to be a mother plans and is ready for the individual challenges that her case might bring.


Physical and blood flow changes

By week eight (after conception) the body’s blood vessels will have widened, allowing a greater volume of blood through them. 

Resistance to blood flow through the body falls by between 30 per cent and 70 per cent. This is followed by fluid retention and an increase in blood volume. This volume expansion alters the ratio of haemoglobin (the protein in red blood cells that carries oxygen) to fluid causing anaemia associated with pregnancy. 

The growing baby must be supplied with nutrients and oxygen, and to meet these demands the heart rate and the stroke volume (the volume of blood pumped from the heart with each beat) will increase.

During labour both the heart rate and stroke volume will increase. Some blood from the uterus will pump into the mother’s blood vessels with every contraction.

A mother will lose blood during delivery and additional blood loss is expected if you have an assisted delivery with suction or forceps and extended episiotomy. After delivery there is an important reabsorption of body fluids back into the blood vessels. This can be a vulnerable time for cardiomyopathy mothers and they need to be monitored.

Nowadays heart disease is a leading cause of maternal death, but in most cases the heart condition was unknown prior to the pregnancy.  In our highly technological and advanced medical world, important lessons need to be learned from this.

Pre-pregnancy counselling

Cardiomyopathy patients are as likely to become pregnant as the general population if they enjoy regular sex. It is therefore advisable for woman of childbearing age to discuss with their heart specialist everything from contraception to the risk of pregnancy.

As cardiomyopathies are inherited conditions, hereditary transmission patterns as well as the likely age for the disease to appear in children and the need for screening them should be clarified.
Your heart specialist will determine if your pregnancy is low risk and you can have similar care to a non-cardiomyopathy mother or if you should be seen at a specialist centre with a cardiologist, obstetrician, neonatologist, anaesthetist and midwife working alongside (a multi-disciplinary team).

Your cardiologist will determine

  • The type of cardiomyopathy
  • The current clinical situation
  • Prognosis and risk of sudden death
  • Risk of blood clots                       

And he or she will review

  • Symptoms and need of medication
  • Signs of fluid overload or heart failure


If the patient is on medication, it is important to discuss side effects and contra-indicated drugs while pregnant. Some medications can harm the baby. Some heart failure medication (such as ACE inhibitors) cannot be taken throughout pregnancy. Other drugs are better avoided in the first three months, but with monitoring can be used in later stages if required (such as warfarin). 

Some patients find it impossible to stay symptom-free without medication. Sometimes surgery or other treatment might need to be explored before a pregnancy is planned.


The natural history of cardiomyopathy also has to be explored when planning a pregnancy. Patients with mild restrictive features but normal lung pressures can go through pregnancy without any major problems but might have heart failure symptoms if the pregnancy is attempted later on when the lung arteries have started to harden.

Your doctor will explain the risk of pregnancy from the heart point of view as well as the likelihood of the pregnancy reaching full term. If there is a serious worsening of heart failure symptoms, jeopardising blood supply to the baby, an early delivery will be discussed.

Your doctor will be looking into evaluating risk for the mother and baby according to the following guides.

Predictors of risk to the mother

  • Previous cardiac event (cardiac arrest, heart failure, stroke or mini-stroke) or arrhythmia
  • More severe heart failure, with shortness of breath on mild exertion
  • Obstruction to the flow of blood from the left side of the heart, such as mitral or aortic valve problems, or left ventricular outflow tract obstruction
  • Reduced pumping function (ejection fraction of less than 40 per cent)

Predictors of risk to the baby

  • More severe heart failure in the mother, with shortness of breath on mild exertion
  • Obstruction to the flow of blood from the left side of the heart
  • Mother’s smoking
  • Multiple birth
  • Mother being treated with blood thinners during pregnancy

Care in pregnancy

Your obstetric team will monitor your pregnancy and it is important to let them know about your heart condition from the start.  They will liaise with your GP, cardiologist or the multidisciplinary team. Your cardiologist will be able to provide timely clinical evaluations of the heart as well as the required tests of pregnancy.

Women who develop heart failure during pregnancy need close monitoring as well as medication like diuretics to balance the fluid overload on their lungs. Their heart rate might increase more than desired and so require betablockers. Sudden unexpected arrhythmias might require emergency hospital admission and external cardioversion (an electric shock to return heart rhythm to normal).


Vaginal delivery with or without a low dose epidural is the preferred form of delivery in most cases. Caesarean section under general anaesthetic might be needed in emergency cases and when the stress of the vaginal delivery is not recommended. It might also be needed if the baby has to be delivered early because of problems in the baby or mother.


The first 24 hours and up two weeks after birth are crucial periods for heart adjustments. Patients can develop acute heart failure symptoms during this time due to the important shift of body fluids back into the blood vessel circulation. Other factors like prolonged deliveries, increased bleeding, and multiple births play an important role in the mother’s health in the first few days. Some women will be advised to stay longer in hospital to help their hearts recover as much as possible.

Amid the joy of a new baby, there will be tiredness and the need for recovery and looking after the baby round the clock as well as yourself. It is advisable to plan to get help in during these early stages. Breastfeeding is advisable, although medication may need to be reviewed to protect the baby. If the baby is premature, bottle-feeding may be the best option.

Difficult decisions

Although the decision to go ahead with a pregnancy is down to the mother, a doctor might feel the risks are too high and the likelihood of a healthy baby being delivered safely are small. Then the mother may be advised against continuing the pregnancy. It is important to be aware that there are specialist centres to support high risk pregnancy and a referral to this type of unit is appropriate either for pre-counselling and follow-up care or support for the very difficult decision of having a termination.

Read our article on pregnancy care for women with cardiomyopathy by Dr Fiona Walker.