Obesity during pregnancy raises the risk of birth defects

Obesity has become a common complication of pregnancy. About one-third of U.S. women of reproductive age are obese, according to recent data. Obesity during pregnancy raises the risk of numerous problems for the mother, such as hypertension and diabetes, and for the baby, such as preterm birth. It also increases the chances that the baby will have a birth defect.

A report in the Journal of the American Medical Association reviewed 39 studies exploring the association between obesity during pregnancy and birth defects. The researchers, from Newcastle University in the United Kingdom, found babies of obese women had twice the risk of having a neural tube defect and an elevated risk of a heart defect, cleft palate or cleft lip, anorectal atresia (an abnormality of the anus or rectum), hydrocephaly (an enlargement of the ventricles of the brain due to fluid) and limb reduction defects.

A study published in 2007 in the Archives of Pediatric and Adolescent Medicine also found a link between obesity in pregnancy and birth defects. It concluded that 4 percent of infants of obese women have birth defects compared with 3 percent of all infants.

Birth defects are responsible for about 20 percent of all infant deaths in the United States. Researchers aren't sure what it is about obesity that may lead to birth defects. One possibility is that undiagnosed diabetes is contributing to the problem or that the mother may have some type of nutritional deficiency.