Frozen embryo transfer outcomes decline with increasing female body mass index in female but not male factor infertility: analysis of 56,564 euploid blastocyst transfers

Abstract

ObjectiveTo evaluate the association of body mass index (BMI) with cycle outcomes after euploid frozen blastocyst transfer. DesignRetrospective cohort study. SettingNot applicable. Patient(s)A total of 56,564 first single autologous euploid frozen embryo transfers (FET) from the 2016-2019 Society for Assisted Reproductive Technology database were analyzed by BMI and by World Health Organization BMI cohorts. Sub-analyses were performed on cycles among patients with a sole diagnosis of polycystic ovary syndrome (PCOS) (n = 4,626) and among patients with only male factor (n = 10,854). Intervention(s)None. Main outcome measure(s)Clinical pregnancy, pregnancy loss, and live birth. Results(s): Success rates and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for all outcomes were most favorable among those with normal BMI and progressively worsened with increasing BMI. These trends persisted among patients with PCOS for clinical pregnancy (aOR 0.99, 95% CI 0.98-0.997, p 0.003), pregnancy loss (aOR 1.02, 95% CI 1.01-1.04, p 0.01), and live birth (aOR 0.98, 95% CI 0.97-0.99, p <0.001), but not among patients with male factor only for clinical pregnancy (aOR 1.00, 95% CI 0.99-1.01, p 0.425), pregnancy loss (aOR 1.01, 95% CI 0.99-1.03, p 0.07), or live birth (aOR 0.99, 95% CI 0.98-1.00, p 0.08). Conclusion(s): In the largest cohort to date, increasing BMI was associated with decreased pregnancy and live birth and increased pregnancy loss following euploid FET among the entire cohort and among patients with a sole diagnosis of PCOS; however, these results were attenuated among patients with a sole diagnosis of male factor infertility, suggesting that associated female infertility diagnoses and not BMI alone may underly this trend.