Risk of neural tube defect-affected pregnancies among obese women.
OBJECTIVE
To investigate the risk for neural tube defect (NTD)-affected pregnancies among obese women (ie, women with a body mass index [BMI] > 29kg/m2) compared with women of average prepregnancy weight.


METHODS
Population-based case-control study.


METHODS
All hospitals in 55 of 58 counties in California.


METHODS
In-person interviews were conducted with mothers of 538 (88% of eligible) NTD cases (including fetuses and infants electively terminated, stillborn, or born alive) and with mothers of 539 nonmalformed controls (88%) within an average of 5 months from the term delivery date.


METHODS
The risk of an NTD-affected pregnancy among obese women.


RESULTS
Compared with women whose BMI was less than or equal to 29 kg/m2, an increased risk for NTD-affected pregnancy was observed among obese women (odds ratio, 1.9; 95% confidence interval, 1.3 to 2.9). The increased risk was not attributable to maternal nonuse of a vitamin containing folic acid, diabetes, use of diet pills, lower dietary folate intake, or an NTD-pregnancy history. Adjustment for maternal age, education, gravidity, use of vitamins, and use of alcohol did not change the odds ratio. The risk associated with maternal obesity was greater for spina bifida and for other less prevalent NTDs than for anencephaly.


CONCLUSIONS
Because as many as 10% of women may be obese periconceptionally, the observed twofold increased risk is relevant to the population burden of NTDs.
Shaw
G M
GM
March of Dimes Birth Defects Foundation, California Birth Defects Monitoring Program, Emeryville, CA 94608, USA.
Velie
E M
EM
Schaffer
D
D
D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D005315:Fetal Diseases; D006801:Humans; D007231:Infant, Newborn; D009436:Neural Tube Defects / Q000453:epidemiology; D009765:Obesity; D016017:Odds Ratio; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D012307:Risk Factors