Obesity during pregnancy linked with risk of birth defects

An analysis of previously reported studies has found that women who are obese during pregnancy have an increased risk of delivering a child with such birth defects as spina bifida and neural tube defects, although the absolute increase in risk is likely to be small.
Doctors conducted a review and meta-analysis of studies to assess the relationship between maternal overweight and obesity and the risk of congenital anomaly in newborns. The researchers identified 39 articles that were included in a systematic review and 18 articles in the meta-analysis.

“In women who were obese at the start of pregnancy, the meta-analysis demonstrated a significantly increased risk of a pregnancy affected by a neural tube defect [nearly twice the odds], including spina bifida [more than twice the odds]; cardiovascular anomaly, including a septal anomaly [heart defect]; cleft palate and cleft lip and palate; anorectal atresia [abnormality of the anus/rectum]; hydrocephaly [abnormal enlargement of the ventricles of the brain due to accumulation of cerebrospinal fluid]; and a limb reduction anomaly,” the doctors reported.
The risk of gastroschisis among obese mothers was significantly reduced. “Given the findings of this review, and the BMI profile of the female population during the period when these estimates were generated, we calculate that the absolute risk of a pregnancy affected by a neural tube defect or a serious heart anomaly is respectively 0.47 per 1,000 births and 0.61 per 1,000 births greater in an obese woman than a woman of recommended BMI in pre-pregnancy or early pregnancy. This has health implications, particularly given the continued rise in the prevalence of obesity in many countries,” the doctors noted.
JAMA
2009;301:636-650