Maternal obesity associated with neural tube defects

Clinical Question

Is maternal obesity associated with an increased risk for neural tube defects in offspring?

Bottom Line

There is an association between maternal obesity and neural tube defects in their children with a dose-response gradient (increasing risk with increasing body mass index) that persists after adjustment for known confounders. Intervention studies are needed. (LOE = 1a-)


Rasmussen SA, Chu SY, Kim SY, Schmid CH, Lau J. Maternal obesity and risk of neural tube defects: a metaanalysis. Am J Obstet Gynecol 2008;198:611-619.  [PMID:18538144]

Study Design

Meta-analysis (other)




Various (meta-analysis)


Observational studies regarding the association between neural tube defects and maternal obesity have had inconsistent results. These authors conducted a meta-analysis of the published literature to synthesize the evidence. They identified 12 cohort and case-control studies that met their inclusion criteria of reporting obesity measures before pregnancy weight gain, had comparison group of normal weight women, and reported the outcome of neural tube defects. All but 2 studies were conducted in the United States. Neural tube defects were defined as spina bifida, anencephaly, encephalocele, craniorachischis, or iniencephaly. The authors calculated unadjusted odds ratios of 1.22 (95% CI, 0.99-1.49), 1.70 (1.34-2.15), and 3.11 (1.75-5.46), among overweight, obese, and severely obese women. Adjustments to account for other variables did not meaningfully change the results.