Maternal Prepregnancy Body Mass Index and Risk of Neural Tube Defects: A Population-Based Case–Control Study in Shanxi Province, China

Background:
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.

Methods:
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.

Results:
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.

Conclusions:
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.


Journal Reference:
Maternal Prepregnancy Body Mass Index and Risk of Neural Tube Defects: A Population-Based Case–Control Study in Shanxi Province, China,Zhiwen Li et al., Birth Defects Research (Part A) 88:570–574, 2010.

Tea Drinking as a Risk Factor for Neural Tube Defects in Northern China

Background:
Tea catechins inhibit the activity of the enzyme dihydrofolate reductase, which catalyzes the inactive form of folate 7,8-dihydrofolate to the active form of folate 5,6,7,8-tetrahydrofolate. This inhibition leads to disturbance of the folate metabolic pathway and to lower bioavailability of folate to cells; therefore, it may increase the risk of neural tube defects (NTDs) in a developing embryo. We examined the association between tea drinking during the periconceptional period and the risk of NTDs.

Methods:
Cases were fetuses or neonates with an NTD as ascertained through a population-based surveillance system in 4 rural counties of Shanxi Province in northern China during 2002 through 2007. Controls were term infants without congenital malformations. Demographic, reproductive, and exposure data were obtained through a face-to-face interview.

Results:
A total of 631 NTD cases and 857 controls were included in the analysis. Compared with women who did not drink tea during the periconceptional period (487 cases and 688 controls), women
who drank tea daily (20 cases and 9 controls) had a 3-fold increased risk (odds ratio 3.1 95% confidence interval 1.4 –7.0 ) of having an NTD-affected pregnancy. The elevated risk associated
with daily tea drinking remained after adjusting for maternal age, educational level, occupation, and periconceptional folic acid supplementation (3.4 1.4–8.3 ). The association was present for all 3 major subtypes of NTDs (ie, anencephaly, spina bifida, and encephalocele).

Conclusions:
Daily tea drinking during the periconceptional period was associated with an elevated risk of NTDs in this Chinese population.


Journal Reference:
Tea Drinking as a Risk Factor for Neural Tube Defects in Northern China, Rongwei Ye et al., Epidemiology 2011;22: 491–496)