Obesity is a risk factor for early pregnancy loss after IVF or ICSI

Background. Experience with polycystic ovary syndrome shows that insulin resistance is related to early pregnancy loss. This association was examined by comparing pregnancy outcome in obese and lean women. Methods. A cohort of 383 patients conceiving after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) was studied. Ovarian stimulation was achieved by GnRHa and FSH or hMG (n=362), by FSH or hMG alone (n=16), or by clomiphene citrate and FSH or hMG (n=5). Luteal phase was supported with progesterone. Pregnancies were defined by >10 IU/I plasma beta-hCG on day 14. Ultrasound scan on week 6 and week 12 confirmed fetal viability. Results. Lean group (body mass index [BMI]<25 kg/m(2); n=304) and obese group (BMI greater than or equal to 25 kg/m(2); n=79) were established. Obese patients had fewer oocytes collected (median: 8 vs 10 p=0.03), they had higher abortion rate during the first 6 weeks (22% vs 12%; p=0.03) and lower live-birth rate (63% vs 75%; p=0.04). The relative risk of abortion before week 6 was 1.77 (95% CI: 1.05 to 2.97). Multivariate logistic regression analysis revealed that obesity and low oocyte count were independently associated with spontaneous abortion. In the obese group, low oocyte number was associated with a more profound increase in the risk of abortion than among lean patients. The effect of age, history of past pregnancies, or infertility diagnosis on the probability of miscarriage were not significant. Conclusions. Obesity is an independent risk factor for early pregnancy loss. This risk is, in part, related to the lower number of collected oocytes in obese women.