What Causes CHD?

If you have had a child born with Congenital Heart Disease you may be asking yourself this question. “What is my risk of having a second child with CHD?” It’s a hard question to answer since there simply isn’t enough research out there on what exactly causes CHD in the first place. Approximately 85% of CHDs have no known cause or origin. In these cases it is theorized that a form of multi-factorial inheritance is at play. This means that a possible combination of genetics from both parents and unknown environmental factors are involved in causing the defect. 

Theorized “multi-factorial inheritance” is about as vague as doctors can be on the issue! This is a huge gray area in the world of CHD. We just simply don’t have enough research to know what causes most congenital heart defects to occur.

Heart warrior Calvin with heart healthy sister, Addie.

Will I have a Second Child with CHD?

If you have done genetic testing and your child’s particular CHD has no known genetic links then your risk of having a second child with CHD is likely low. Statistically, your risk is increased by 2-3%. We know CHD occurs in approximately 1 in 100 births so your risk of having a second child with CHD is approximately 2-3 in 100. Remember, the 1 in 100 statistic also includes more minor defects like small holes that never need any intervention. 

CHDs with Known Genetic Links

If your child’s CHD does have a known genetic link (especially if one parent has a CHD) then your risk of having a second child with CHD is higher. The risk will vary widely depending on the cause. Heart defects that are part of a syndrome are often due to single gene defects. They can be more likely to run in families. Some examples of these syndromes are:

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

More research is emerging on the genetic link between certain left-sided heart defects. It is now known that there is some kind of genetic link between Hypoplastic Left Heart Syndrome and Bicuspid Aortic Valve. Researchers are still unsure what the link is.  But, HLHS and BAV both tend to occur in families together at a higher rate. 

Precautions to Take

If you, your spouse, or any family member have CHD it’s important to look for heart defects in utero to be as prepared as possible at the time of birth. Talk to your doctor about having an anatomy scan between 18-22 weeks gestation and an additional fetal echocardiogram between 18-24 weeks. The fetal echo is a higher level ultrasound that will look more in-depth at the heart’s structures and function. Not all types of CHD can be visualized in utero even during a fetal echo so your baby may also need an echo repeated after birth.