Pregnancy puts quite a strain on the heart, and your heart needs to do a significant amount of extra work. For your heart, it’s as if you are doing exercise, but doing it for 9 months! Your heart beat will be faster than normal and your heart will need to pump more blood around – for the last 3 months of the pregnancy this means pumping 40% more blood than usual.

Pregnancy also has other effects on the heart, meaning that you are more prone to abnormal fast heart rhythms, blood clots are more likely, and fluid retention can become a problem for women with heart conditions.

The effect of pregnancy can be very different in women with different types of congenital heart conditions. For some women we would expect your heart to cope well with pregnancy, but for others we know that complications are more likely to occur. In some cases the risk from pregnancy may be so high that we recommend avoiding pregnancy altogether.

Your cardiologist is an expert in heart disease, and they will know the details of your condition. They can explain to you the effect that pregnancy might be expected to have on your health and what complications may occur. They will sometimes recommend that you also talk to an obstetric physician before you try to become pregnant: obstetric physicians are experts in looking after women with other health conditions during a pregnancy. If the team thinks that pregnancy will be dangerous for you, they may advise you not to become pregnant. The cardiology and obstetric medicine teams will make sure that you are well informed so that you have all the facts available, but ultimately this is a decision only you can make, in conjunction with your partner.

It is very important that full testing is carried out before you try for a pregnancy, to determine how well your heart is working. This will enable us to give you the most accurate advice, and the information obtained will help us to plan your care during a pregnancy.

The tests we recommend will include the regular ones, like echo scans and ECGs, but may also include an MRI scan and an exercise test. Sometime we may want to do a heart catheter too.

You should be seen very early in your pregnancy, ideally at about eight weeks from the beginning of your last period. In most cases your pregnancy will be jointly supervised by a cardiologist and either an obstetrician or an obstetric physician.

Depending on the type of heart condition you have, you are likely to need to be seen more frequently than most women during pregnancy. Sometimes this may mean you see your cardiologist two or three times during the pregnancy, but in some cases we will see you every month, or even more. This way, we will be more likely to pick up early signs of any problem developing.

At each visit, we will ask you similar questions to a normal clinic – shortness of breath, exercise tolerance, palpitations etc. We will examine you and will often do tests like an ECG and echo scan at some stages during the pregnancy. Again, the exact tests that we do will depend on your particular heart condition.

Regular scans to check on the growth of the baby will probably be necessary. If there is any anxiety about your condition, or that of your baby, you are likely to be admitted to hospital for rest and tests. Some women with more major heart conditions will find that they become very tired as the pregnancy progresses and may need to be admitted to hospital for extra rest. In rare cases this can mean being in hospital for a few weeks towards the end of the pregnancy.

The heart pumps blood around the body, and the blood carries oxygen and nourishment to the placenta in order to supply the baby’s needs. If your heart is not working as well as normal, the developing baby may not get all the oxygen and nutrition it needs. The result of this is that the baby may not grow as well as normal (fetal growth restriction) or it may be born premature.

With good neonatal care, many small babies can do well after they are born, but some may have a permanent handicap. For a few, this will be severe. You need to consider how you would cope with this if it happens.

In addition, the tendency to have a heart defect is hereditary; if you have one your baby will probably have a 3–5% risk (one in 20) of having one too (the risk varies somewhat, depending on your heart condition – we can advise you about your own risk). This is about five times the average risk. If your partner has a heart problem, the risk is even higher. Nowadays, up to 80% of heart abnormalities can be detected using ultrasound scanning. This will be offered to you between 11 and 24 weeks of the pregnancy (the later the scan, the bigger the baby, and the more detail can be seen). If an abnormality is detected, you may be able to consider terminating the pregnancy. You will need to decide how you feel about this.

For most women with congenital heart disease, natural vaginal delivery, if it goes well, is the safest way to give birth. Giving birth does put extra strain on the heart, but there are things that we can do to try to limit the extra demands on your heart, and for this reason good pain relief is very important and we will often recommend an epidural. Also, pushing the baby out at the end of labour can be very exhausting, so we sometimes recommended that this part is assisted by the doctors using either a suction cup or forceps on the baby’s head.

In some cases we will recommend a caesarean section if the particular type of heart condition that you have would make vaginal delivery more risky. Some women will also be recommended to have a caesarean section for the same reasons as in other pregnant women, but not for heart reasons.

The first couple of weeks after a baby is born is a time when lots of changes take place with your body. This means that women with congenital heart conditions can run into problems during this period and we may recommend that you stay in hospital for longer than usual for monitoring.

Fluid retention is common during this period and we may give medications to help you shift extra fluid if this occurs. Blood clots in the veins of the leg are more common after birth and you will probably be given injections to thin the blood slightly (heparin) until you are up and about normally.

We will also discuss contraception before you go home. It is important to consider starting contraception before your fertility returns and this may be as early as four weeks after delivery if you are not fully breastfeeding.