A national study of the effect of increasing obesity on the response to and outcome of assisted reproductive technology (ART)

OBJECTIVE: To evaluate the effect of increasing female obesity on the response to and outcome of ART treatment.DESIGN: Retrospective cohort study.MATERIALS AND METHODS: The study population included 158,385 ART cycles from the Society for Assisted Reproductive Technology Clinical Online Reporting System for 2007-08 and was limited to women with both height and weight recorded. Women were categorized by their body mass index (BMI, weight/height2) as underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), and obese (30.0-34.9, 35.0-39.9, 40.0-44.9, 45.0-49.9, and ≥50.0). Logistic regression was used to model the odds of cycle cancellation overall, cycle cancellation due to low response, not pregnant as the treatment outcome, and fetal loss or stillbirth as the pregnancy outcome, as adjusted odds ratios and 95% confidence intervals, with normal weight women as the reference group. Models were adjusted for maternal age, race and ethnicity, height, infertility diagnoses; treatment and pregnancy models were additionally adjusted for oocyte source and state, and number of embryos transferred.RESULTS: Compared to normal weight women, the odds of both cycle cancellation overall and cancellation due to low response significantly paralleled increasing obesity, despite higher dosages of follicle stimulating hormone. These odds rose from 1.05 and 1.11 for overweight women to 1.92 and 2.18 for women with BMIs ≥50.0, respectively. The odds of treatment failure (not pregnant) and pregnancy failure (fetal loss or stillbirth) also increased significantly with rising BMI, from 1.04 and 1.12 for overweight women to 1.50 and 2.23 for women with BMIs ≥50.0, respectively.CONCLUSION: These results indicate significantly higher odds of cycle cancellation, and treatment and pregnancy failures with increasing obesity. These effects are greatest among the heaviest women, but are also significantly higher even among overweight women. OBJECTIVE: To evaluate the effect of increasing female obesity on the response to and outcome of ART treatment. DESIGN: Retrospective cohort study. MATERIALS AND METHODS: The study population included 158,385 ART cycles from the Society for Assisted Reproductive Technology Clinical Online Reporting System for 2007-08 and was limited to women with both height and weight recorded. Women were categorized by their body mass index (BMI, weight/height2) as underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), and obese (30.0-34.9, 35.0-39.9, 40.0-44.9, 45.0-49.9, and ≥50.0). Logistic regression was used to model the odds of cycle cancellation overall, cycle cancellation due to low response, not pregnant as the treatment outcome, and fetal loss or stillbirth as the pregnancy outcome, as adjusted odds ratios and 95% confidence intervals, with normal weight women as the reference group. Models were adjusted for maternal age, race and ethnicity, height, infertility diagnoses; treatment and pregnancy models were additionally adjusted for oocyte source and state, and number of embryos transferred. RESULTS: Compared to normal weight women, the odds of both cycle cancellation overall and cancellation due to low response significantly paralleled increasing obesity, despite higher dosages of follicle stimulating hormone. These odds rose from 1.05 and 1.11 for overweight women to 1.92 and 2.18 for women with BMIs ≥50.0, respectively. The odds of treatment failure (not pregnant) and pregnancy failure (fetal loss or stillbirth) also increased significantly with rising BMI, from 1.04 and 1.12 for overweight women to 1.50 and 2.23 for women with BMIs ≥50.0, respectively. CONCLUSION: These results indicate significantly higher odds of cycle cancellation, and treatment and pregnancy failures with increasing obesity. These effects are greatest among the heaviest women, but are also significantly higher even among overweight women.