Cumulative Live Birth Rates According to Maternal Body Mass Index After First Ovarian Stimulation for Fertilization: A Single Center Analysis of 14,782 Patients.

To investigate the cumulative live birth rates (CLBR) according to body mass index (BMI) in women undergoing their first fertilization (IVF). Retrospective cohort analysis. An IVF clinic in a public hospital. This is a retrospective study of 14,782 patients undergoing their first fresh IVF cycles and subsequent frozen embryo transfers in our clinic from January 2014 to January 2017. The follow-up for CLBR continued until January 2019. Patients with a BMI <18.5 kg/m were considered to be underweight and those with a BMI > 24 kg/m were considered to be overweight. Patients with a BMI ≥ 28 kg/m were considered to be obese. None. The primary outcome was cumulative live birth rate (CLBR). This study illustrated the "inverted U shape" associations between body weight and IVF outcome (CLBR). The turning points in threshold analysis, as found by an automatic search, were BMIs of 18.5 and 30.4 kg/m. The main finding of this retrospective data analysis is that the CLBR increased in underweight women, plateaued for normal weight and overweight women with a BMI between 18.5 and 30.4 kg/m, and decreased in obese women. The data suggested an "inverted U shape" association between BMI and CLBR. The CLBR increases in underweight women, plateaus in normal weight and overweight women, and then decreases in obese women.