Congenital heart disease, a structural defect in the heart, affects 1% of newborns. Approximately 25% of these heart defects are serious, meaning some intervention will be needed soon after birth (many heart defects involve small openings between the chambers of the heart and often close on their own as your baby grows). These more serious defects cause of 4.2% of deaths in the first 28 days of life (neonatal deaths).
The heart starts as a tube very early in pregnancy. The heart is remodeled several times during pregnancy to become the complex structure that we have at birth. Because there are so many complex structural changes, there is more room for construction error, and so the heart is the organ most likely to have a congenital defect (a structural problem).
Premature babies are three times more likely to have a congenital heart defect than babies born at term. For babies who weigh less than 1,000 g at birth the incidence of congenital heart disease is as high as 6.5% (six times higher than a term baby).
Why are preemies more likely to have congenital heart disease? No one knows for sure, but there are several possible reasons:
- Many babies with CHD as smaller than expected, which may lead to being induced early because of concerns over growth.
- Some babies with CHD have other birth defects or chromosomal problems. For reasons unknown, this can lead to premature labor. Babies with multiple birth defects or chromosomal problems may also be smaller, leading to an induction because of concerns over growth
- Prematurity and congenital heart diseases share some similar risk factors, such as nutritional deficiencies and smoking. There are probably many shared risk factors that we still don’t know about.
- There may be some unknown factor with congenital heart diseases that triggers early labor.
- Identical twins are at higher risk for heart defects, especially those twins who develop twin-to-twin transfusion (TTTS) syndrome. In one study, the risk of congenital heart disease was 9 times higher among twins with TTTS. Twins with TTTS are more likely to be delivered prematurely due to complications of this condition.
Check out tomorrow’s post for information on CHD screening in preemies.