The effect of body mass index on the outcomes of first assisted reproductive technology cycles.

OBJECTIVE: To provide assisted reproductive technology (ART) outcome rates per body mass index (BMI) category after controlling for potential confounders.
DESIGN: Retrospective cohort study.
SETTING: Large university-affiliated infertility practice. PATIENT(S): Women undergoing ART. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The primary outcome was live birth. Analyses were stratified according to BMI category and adjusted for potential confounders, including maternal and paternal age, baseline serum FSH, duration of gonadotropin stimulation, mean daily gonadotropin dose, peak serum E(2), number of oocytes retrieved, use of intracytoplasmic sperm injection, embryo quality and number, transfer day, and number of embryos transferred. RESULT(S): We analyzed the first autologous fresh IVF or IVF-ICSI cycle of 4,609 patients. There were no differences in the rates of cycle cancellation, spontaneous abortion, biochemical and ectopic pregnancies, or multiple births. After adjusting for potential confounders, patients with BMI ≥ 30.0 kg/m(2) had significantly decreased odds of implantation, clinical pregnancy, and live birth. The adjusted odds ratio (95% confidence interval [CI]) of live birth were 0.63 (0.47-0.85) for BMI 30.00-34.99, 0.39 (0.25-0.61) for BMI 35.00-39.99, and 0.32 (0.16-0.64) for BMI ≥ 40.0 compared with normal-weight cohorts. CONCLUSION(S): Obesity has a significant negative effect on ART outcomes. Patients with BMI > 30 kg/m(2) have up to 68% lower odds of having a live birth following their first ART cycle compared with women with BMI < 30.