Insogna IG, et al. - The purpose of this study was to investigate the impacts of body mass index (BMI) on implantation rate after uniform protocol frozen-thawed blastocyst transfer in women with a homogenous uterine environment. Under highly controlled circumstances across 7 years of information from a single institution, utilizing a uniform uterine preparation, following a precise transfer technique with high-quality day 5-6 slow frozen-thawed blastocysts, a BMI in the overweight range of 25-29.9 kg/m² is not related to a poorer implantation rate or live-birth rate, nor it is related to an increased risk of miscarriage when compared with a normal BMI range. The increased length of time required amid transfer for women with higher BMI proposes that body habitus may contribute to difficult transfers, although this may not translate into poorer implantation rates. By utilizing a standardized protocol for slow freezing and thawing of embryos, utilizing identical hormonal preparation and a uniform ET protocol, a homogenous uterine environment was created in this carefully selected cohort of women, thereby minimizing confounders and uniquely featuring the neutral impact of overweight BMI on implantation rate.