Heart babies Dr Helena Gardiner One baby in 100 is born with heart or circulation problems. With improvements in ultrasound scan techniques, most of these can now be detected while the baby is still developing in the womb.

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Causes and risk factors Diagnosis

Specialist care Further information

It's medical belief that most heart problems in babies are due to faulty genes. From conception, when sperm and egg combine, a complex construction process occurs to create a human embryo. We all carry a small number of faulty genes and if there's a fault in the gene signalling, a structural heart problem may appear.

In small communities, where relatives are more likely to marry, there is less variation in the genes and it is more likely that both parents will carry the same rare genetic faults This situation is known as a small gene pool, and it is dangerous because genetic conditions such as heart abnormalities are more likely to occur. In larger communities where there is more mixing of different genes, genetic problems are less common.

A proportion of babies with heart malformations have problems with the chromosomes which can be detected by tests during pregnancy, providing an early clue that the child may be at particular risk. For example, many pregnant women are screened for Down's syndrome (where there are 3 rather than 2 copies of chromosome number 21) in which up to 40% of babies are born with a heart problem.

There are other causes of congenital heart disease too: for example, mothers with diabetes have a two per cent chance of having a baby with heart problems.

Most of the babies born with heart problems don't come from high-risk groups. The reason is simply that this is a comparatively rare, almost unpredictable condition - and there are only small numbers of high-risk people in the population.

The majority of heart problems in babies are detected at a routine ultrasound scan, usually at 18 to 20 weeks, although some aren’t discovered until after the birth. If you have worries, talk to your GP or obstetrician. If they suspect problems they may refer you to a specialist unit for further tests.

At about 19 weeks gestation, a baby's heart is less than a centimetre across and weighs only 1g or so (compared with 500g for an average adult heart). It also beats more than twice as fast as an adult's.

The circulation of a foetus is different from that of a newborn baby, being connected to a placenta and having three extra channels that must close or reverse at birth.

Good quality ultrasound equipment is essential to look at the tiny, fast-moving cardiac structures. Even so, ultrasound images appear grainy - it requires practice and an experienced eye to identify problems.

Advances such as the colour flow doppler detect the movement of red blood cells, highlighting areas of abnormal blood flow that may indicate circulation problems. These may have been missed by a conventional scan.

There are a small number of specialist foetal medicine units where experts can help mothers and their unborn babies. In these units, the heart and circulation of the foetus can be examined by ultrasound, in a procedure known as foetal echocardiography.

The advantage of these units is that when a cardiac malformation is associated with additional structural or chromosomal problems (as they often are) there are several different specialists available on the team to work together to provide the best care.

If surgery is necessary, an appointment with the cardiac surgeon in the cardiology centre is helpful to prepare parents for the perinatal period (the time just before and after the birth) and to discuss surgical issues. Specialist liaison nurses provide additional support for parents at this time, and good communication with the local obstetric unit and local paediatricians is essential.

Greater recognition and understanding of cardiac disease in the early stages of life should mean safer management before and at the time of birth leading to better results for heart babies. For example, treatments to open valves safely before birth are in development and fast heart rates can be treated using drugs.

As our knowledge of the development of babies during pregnancy improves, doctors will be able to offer better care.

Tiny Tickers is a charity aimed at improving our understanding of foetal heart problems. Its objectives are to raise awareness, promote research and support those affected by these problems. For more information, go to www.tinytickers.org.

Other organisations that can provide help and support include:

British Heart Foundation

Tel: 0845 070 8070
Website: www.bhf.org.uk

Little Hearts Matter

Tel: 0121 455 8982
Website: www.lhm.org.uk

Grown Up Congenital Heart Patients Association

Tel: 0800 854759
Website: www.guch.org.uk

This article was last medically reviewed by Dr Trisha Macnair in February 2009.