Congenital heart disease (CHD) is a term used to describe a variety of heart defects that are present at birth. These defects can affect the structure of the heart, the way it pumps blood, or the way blood flows through the heart and blood vessels.
The exact cause of CHD is not always known, but there are several factors that can increase the risk of a baby developing CHD. Some of these include:
GENETIC FACTORS: Some forms of CHD are inherited and run in families. Genetic mutations or changes in certain genes can increase the risk of CHD.
- Down’s syndrome is the most widely-known genetic condition that can cause congenital heart disease. Children with Down’s syndrome are born with a range of disabilities as the result of a genetic abnormality. About half of all children with Down’s syndrome have congenital heart disease. In many cases, this is a type of septal defect.
- Turner syndrome – a genetic disorder that only affects females; many children with Turner syndrome will be born with congenital heart disease, which is usually a type of valve or artery narrowing problem.
- Noonan syndrome – a genetic disorder that can cause a wide range of potential symptoms, including pulmonary valve stenosis.
MATERNAL HEALTH: Certain maternal health conditions, such as diabetes or rubella, can increase the risk of CHD.
- Maternal diabetes: Women with diabetes have a higher risk of giving birth to a baby with congenital heart disease than women who don’t have diabetes. This increased risk only applies to type 1 diabetes and type 2 diabetes. It doesn’t apply to gestational diabetes, which can develop during pregnancy and usually disappears once the baby is born. The increased risk is thought to be caused by high levels of the hormone insulin in the blood, which may interfere with the normal development of a foetus (the early stages of the baby developing in the womb).
- Rubella: Rubella (german measles) is an infectious condition caused by a virus. It isn’t usually a serious infection for adults or children, but it can severely affect an unborn baby if a mother develops a rubella infection during the first 8 to 10 weeks of pregnancy. A rubella infection can cause multiple birth defects, including congenital heart disease. All women of childbearing age should be vaccinated against rubella.
- Flu (influenza): Women who get flu during the first trimester (3 months) of pregnancy are at greater risk of having a baby with congenital heart disease than the general population. The reasons for this are unclear. The flu vaccine is recommended for all pregnant women.
MEDICINES: There are several medicines linked to an increased risk of a baby being born with congenital heart disease. These include:
- certain anti-seizure medicines – such as benzodiazepines (for example diazepam)
- certain acne medicines – such as isotretinoin and topical retinoids (see treating acne for more information)
- ibuprofen – women who take the painkiller ibuprofen when they are 30 or more weeks pregnant have an increased risk of having a baby with a heart problem
Paracetamol is a safer alternative to ibuprofen during pregnancy, although ideally you should avoid taking any medicines while you’re pregnant, particularly during the first 3 months of pregnancy.
ALCOHOL: If a pregnant woman drinks too much alcohol during pregnancy, it can have a poisonous effect on the tissue of the foetus. This is known as foetal alcohol spectrum disorder. Children with foetal alcohol spectrum disorder can have congenital heart disease, such as atrial or ventricular septal defects. The Department of Health and Social Care recommends that pregnant women shouldn’t drink alcohol.
ENVIRONMENTAL FACTORS: Exposure to certain chemicals, drugs, viruses, or toxins during pregnancy can increase the risk of CHD. Women who are exposed to some organic solvents may be more likely to give birth to a baby with congenital heart disease than the general population. Organic solvents are chemicals found in a wide range of products and substances, such as paint, nail polish and glue.
NUTRITIONAL DEFICIENCIES: Maternal deficiency of certain nutrients, such as folic acid, can increase the risk of CHD.
PHENYLKETONURIA (PKU): Phenylketonuria (PKU) is a rare genetic condition present from birth. In PKU, the body can’t break down a chemical called phenylalanine, which builds up in the blood and brain. This can cause learning and behavioural difficulties. PKU can usually be effectively treated with a low-protein diet and dietary supplements. Pregnant mothers with PKU who don’t do this are more likely to give birth to a baby with congenital heart disease than the general population.
It’s worth noting that most congenital heart disease occurs during the first eight weeks of pregnancy, during which the heart is forming. Therefore, most of the risk factors listed above would affect the development of the heart during that time.