ARE OBESE WOMEN AT HIGHER RISK FOR PRODUCING MALFORMED OFFSPRING

OBJECTIVE: Our purpose was to determine whether obese women and underw eight women have an increased risk of birth defects in their offspring . STUDY DESIGN: A geographically based case-control study of women liv ing in California and Illinois was performed. There were 499 mothers o f offspring with neural tube defects, 337 mothers of offspring with ot her major birth defects, and 534 mothers of offspring without birth de fects who participated. RESULTS: Compared with women of normal weight, women who were extremely obese before pregnancy (body mass index grea ter than or equal to 31 kg/m(2)) showed a significantly increased risk of having an infant with a neural tube defect (odds ratio 1.8, 95% co nfidence interval 1.1 to 3.0), especially spina bifida (odds ratio 2.6 , 95% confidence interval 1.5 to 4.5), after adjustments for age, race , education, and family income. Obese women also had significantly inc reased risks (p < 0.05) of having an infant with other defects of the central nervous system, great vessel defects, ventral wall defects, or other intestinal defects. CONCLUSION: Our data suggest that offspring of obese women (but not underweight women) are at an increased risk o f neural tube defects and several other malformations. If these findin gs are confirmed, further research will be necessary before it can be concluded that weight reduction before pregnancy will lower the risk o f birth defects among obese women. Until then, obese women can address their risk of birth defects with the same measures that are recommend ed for all women, such as adequate daily intake of folic acid and alph a-fetoprotein screening to identify malformed fetuses.