Strengths and limitations
To our knowledge, this is the first large-scale study to comprehensively assess the impact of elevated BMI on the short- and long-term outcomes of IVF/ICSI treatment and subsequent FET cycles in a Chinese population. Unlike other studies which have focused exclusively on pregnancy outcomes of fresh cycles as primary outcomes, the most meaningful finding in our study was CLBR. CLBR is a more accurate indicator of the state of oocytes following IVF/ICSI stimulation, which lend credibility and persuasiveness to the results. In addition, to reduce the heterogeneity of the study, only the routine long protocol was included, and PCOS patients were excluded. Nevertheless, there are a few limitations to this study. Our study was race- and region-restricted; a larger and diverse dataset may provide additional insights into the impact of elevated BMI on IVF/ICSI outcomes. In addition, as our birth defects data were gathered through telephone follow-up, many minor defects may have been overlooked, although the overall conclusion is less likely to be affected. Moreover, due to the retrospective nature of the current study, further randomized controlled trials are needed to validate the results.