Obesity and the risk of spontaneous abortion after oocyte donation

Abstract

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 >/=30 (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.