Independent effect of body mass index on clinical pregnancy rate in single blastocyst frozen embryo transfer cycle in Asian women

Introduction: There are limited studies in literature regarding the effect of body mass index (BMI) on clinical pregnancy rate following frozen-thawed embryo transfers. Objective: We aim to study the independent effect of BMI on clinical pregnancy rate in single blastocyst frozen-embryo transfer cycle in Asian women. Material and methods: It is a prospective observational study involving 167 women who underwent single, good quality frozen-blastocyst transfer following a uniform protocol. Stimulation was done by hormone replacement therapy in all cycles. The study population was divided into various cohorts as per the BMI classification for Asian adult population (normal: 18.5–22.9, pre-obese: 23–24.9, obese I: 25–29.9, obese II: ≥30). Results: The positive β-HCG rate was 48.93% in normal BMI women, 55.31% in pre-obese, 50% in obese I, and 38.4% in obese II BMI groups. The clinical pregnancy rate was 36.17% in normal BMI women, 48.93% in pre-obese, 45% in obese I, and 30.07% in obese II BMI groups. The difference between various BMI subgroups as regards to positive β-HCG as well as clinical pregnancy is not statistically significant. Women with BMI ≥ 30 had numerically low clinical pregnancy rate, in comparison to those with lower BMI sub-groups. However, this difference was not statistically significant. Conclusion: This study concludes that BMI did not affect clinical pregnancy rate among women following a uniform protocol, single good quality frozen blastocyst transfer in Asian women. The increased difficulty during transfer for women with higher BMI suggests that body habitus may be responsible for difficult transfers, although this may not translate into a worse clinical pregnancy rate. A study with larger sample size may be needed to confirm these findings.