Descriptive analysis of participants’ characteristics
A total of 1072 LM women and 4219 general IVF women were included in this study. The baseline characteristics of women in each group are shown in Table Ⅰ. Most of the baseline data in subgroups were comparable with the general IVF population (gIVF group). Compared with the gIVF group, women in ceLM group were younger (30.13±3.84 vs. 29.31±3.85, P=0.000). Notably, women in the unLM and ceLM groups had a higher BMI index (23.35±3.63 vs. 24.11±3.85, P=0.001; 23.35±3.63 vs. 25.00±3.97, P=0.000 respectively), and more of them were diagnosed with PCOS (18.82% vs. 25.33%, P=0.001;18.82% vs. 37.86%, P=0.000 respectively), according to basal hormone levels, the number of bilateral antral follicles and previous menstrual history(20).