Obesity and the risk of spontaneous abortion after oocyte donation

Objective: To determine whether obesity increases the risk of spontaneous abortion. Design: Retrospective study. Setting: Oocyte donation program at the Instituto Valenciano de Infertilidad in Spain. Patient(s): Seven hundred twelve cycles of recipients of ovum donation with known body mass index (BMI), good-quality embryo transfer, and absence of uterine pathology or clinical history of antiphospholipid antibodies or recurrent abortion. Intervention(s): Recipients were divided in four BMI (kg/m(2)) groups: lean, with BMI <20 (n = 92; 12.9%); normal, with BMI = 20-24.9 (n = 398; 55.9%); overweight, with BMI = 25-29.9 (n = 172; 24.2%); and obese, with BMI greater than or equal to30 (n = 50; 7%). Clinical parameters were compared among the groups. Main Outcome Measure(s): Spontaneous abortion rates according to BMI. Result(s): No difference was found among the four BMI groups in any of the parameters of the cycle analyzed. The overall abortion rate was 15.8% (57 of 360). There were significant differences in abortion rates between the obese (38.1%), and the normal (13.3%) and overweight (15.5%) groups. When several cutoff BMI values were established (20, 25, and 30), only the obese women demonstrated a greater risk of abortion. Compared with the normal population, the obese group showed a significant fourfold increase in the risk of spontaneous abortion. Conclusion(s): Our findings confirm that obesity (BMI 30) is an independent risk factor for spontaneous abortion. Therefore, it would be advisable for obese patients to reduce weight before becoming pregnant. (C) 2003 by American Society for Reproductive Medicine.