• birth defects;
  • neural tube defects;
  • body mass index;
  • obesity;
  • case–control study



Many studies from the Western world have indicated that maternal obesity is associated with an increased risk of neural tube defects (NTDs). However, few reports have been available on this association from Asian populations. Our aim was to examine the relationship between maternal prepregnancy body mass index (BMI) and the risk of NTDs in a population of northern China.


Data were derived from an ongoing population-based case–control study of birth defects in Shanxi province, China. Subjects were 511 NTD cases and 687 controls selected from the same population between January 2003 and June 2007. BMI was based on maternal height and prepregnancy weight as reported within 1 week of delivery.


We found no significantly increased risk of NTDs for obese women (adjusted odds ratio [OR], 0.65; 95% confidence interval [CI], 0.29–1.49) or for underweight women (adjusted OR, 1.00; 95% CI, 0.62–1.62) relative to normal-weight women. We found a significantly reduced risk of overall NTDs (adjusted OR, 0.56; 95% CI, 0.41–0.76) and anencephaly (adjusted OR, 0.40; 95% CI, 0.26–0.62) for overweight women compared to normal-weight women.


Our results do not support the association between maternal prepregnancy obesity and increased risk of overall NTDs or of any subtype of NTDs in the Chinese population. Birth Defects Research (Part A) 2010. © 2010 Wiley-Liss, Inc.