What causes congenital heart disease?

Congenital heart defects are heart problems that a baby is born with at birth. This is due to an abnormal formation of the heart which occurs while the baby is growing in the womb. There is usually no known reason for a baby being born with a congenital heart defect. Some of these defects are due to an abnormality in the number of a baby’s chromosomes, while others are linked to gene defects or environmental factors. There are many different reasons for a CHD occurring, which is why having CHD Support is so important.

Maternal Factors

Some types of congenital heart defects occur due to substances that the mother comes in contact with during pregnancy. Usually, this is during the first few weeks when the baby’s heart is growing, and the mother may not know she is pregnant. This might be an illness on the mother’s behalf or the medicine she takes. The following increases risk for a child being born with a CHD:

• Seizure disorder and antiseizure medicines
• Lithium to treat depression
• Having phenylketonuria (PKU) and not staying on the PKU diet during pregnancy
• Insulin-dependent diabetes
• Lupus
• Connective tissue disorder
• Pregnancy from assisted reproductive technology (ART)
• Rubella

Family History

1% of all children are born with a congenital heart defect, and there is a three times higher risk for CHD when a first-degree relative has a CHD. Parents with a defect have a 50% chance of passing it on to their children.  This means that it is important to look into counseling with a genetic doctor. Usually, you can do a test during the second trimester, at about 18 to 22 weeks of pregnancy to look for major defects.

Chromosome Abnormalities

Chromosomes are the structures in your cells. They contain your genes. Genes pass on eye colors or blood type. Most people have 46 chromosomes in each cell of the body, but having too many or too few can lead to health problems and birth defects. Another option is a structural defect of the chromosomes. Chromosome problems lead to genetic syndromes like Down syndrome, which generates a higher risk of heart problems in babies. 30% of people with a chromosome syndrome will have a heart defect. 

Chromosome problems linked with CHD include:

• Down syndrome (trisomy 21)
• Trisomy 18 and trisomy 13
• Williams syndrome
• Turner’s syndrome
• Cri-du-chat syndrome
• Wolf-Hirshhorn syndrome
• DiGeorge syndrome (22q11)

Single Gene Defects

There are 70,000 genes on the 46 chromosomes in each cell of the body and genes come in pairs. When a gene mutates, it can cause health problems. When multiple health problems occur from one single genetic cause, it’s called a syndrome. Some of the genetic syndromes that lead to heart defects include:

• Marfan syndrome
• Smith-Lemli-Opitz syndrome
• Ellis-van Creveld syndrome
• Holt-Oram syndrome
• Noonan syndrome
• Mucopolysaccharidoses
• Alagille syndrome

What to do If Your Child is Born With CHD

If your child is born with CHD and has a genetic syndrome, it is best to contact a doctor who specializes in genetics. This will be the best way to choose your course of action.