Clinical outcomes of natural cycle IVF/M with the different sizes of dominant follicle at the time of hCG triggering

There is infertility treatment named natural cycle in vitro fertilization (IVF) combined with in vitro maturation (IVM) of immature oocytes (natural IVF/M). The objective of this study is to investigate the clinical outcomes of hCG triggering at the different sizes of dominant follicle during the treatment. A total of 705 patients with 1,011 natural IVF/M treatment cycles were included in this study. Among these 64 patients had repeated cycles, while 641 patients had only a single cycle. The cycles were divided into 4 groups according to the size of dominant follicle on the day of hCG injection (Group1:≤11.9 mm; Group2:12.0–13.9 mm༛Group3:14.0–15.9 mm༛Group4:≥16.0 mm).Through multivariate logistic regression analysis, candidate factors of number of mature oocytes, available and good quality embryos as well as clinical pregnancy rates were explored. Oocytes maturation, fertilization, cleavage, available and good quality embryo rates (p > 0.05) were no difference among 4 groups. The rates for implantation, clinical pregnancy, miscarriage, premature delivery, and live birth were similar among the groups. The presence and different sizes of the dominant follicle in the ovaries during natural cycle IVF/M does not affect clinical outcomes.