Probability of a Baby Being Born with a Birth Defect

Birth defects affect approximately 1 in every 33 babies born in the United States each year, or about 120,000 babies. Birth defects are the leading cause of infant death, accounting for about 20% of all infant deaths. They are also a leading cause of childhood disability.

The most common birth defects include heart defects (the most common, affecting about 1% of births), cleft lip/palate, Down syndrome, spina bifida, and limb defects. Most birth defects occur during the first three months of pregnancy when organs are forming. About 50% of birth defects have no known cause; the rest are attributed to genetic factors, environmental exposures, or a combination.

Known risk factors include certain medications (e.g., thalidomide, isotretinoin, some anti-seizure drugs), alcohol use during pregnancy (causing fetal alcohol spectrum disorders), infections (e.g., Zika, rubella), uncontrolled diabetes, obesity, and smoking. Folic acid supplementation before and during early pregnancy reduces the risk of neural tube defects by 50-70%. Prenatal screening and diagnostic tests can identify many birth defects before birth.