Aim: To study the influence of maternal body mass index (BMI) on the association between folic acid supplementation and neural tube defects (NTDs) risk in offspring.
Methods: A hospital-based, case-control study was conducted between 2006 and 2008 on 459 mothers with NTDs-affected births and 459 mothers without NTDs-affected births. Logistic regression models examined the associations between folic acid supplementation and the NTDs risk in offspring for all mothers, underweight/normal weight mothers (BMI<24.0) and overweight/obese mothers (BMI ≥24.0). The effects were evaluated by adjusted odds ratio (AOR) and 95% confidence intervals (CIs) with SAS 9.1.3 software.
Results: The overall AOR for periconceptional folic acid supplementation was 0.315 (95% CI = 0.172-0.577) when compared with no supplements. Stratified by maternal BMI, the AOR for periconceptional folic acid supplementation in overweight/obese mothers was greater than in underweight/normal weight mothers (0.646 vs. 0.208). The AOR for folic acid supplementation within 3 months before conception was 0.711 (95% CI = 0.323-1.563) in all mothers. Stratified by maternal BMI, the AOR for folic acid supplementation within 3 months before conception in overweight/obese mothers was greater than in underweight/normal weight mothers (0.658 vs. 0.527).
Conclusion: The association between folic acid supplementation and the reduced NTDs risk was weaker in overweight/obese mothers (BMI ≥24.0) than in underweight/normal weight mothers (BMI <24.0).
Keywords: Body mass index; Folic acid; Neural tube defects.
©2013 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.