[Effect of baseline LH/FSH ratio in PCOS on IVF-ET outcomes: a retrospective cohort study].

Objective: To exlplore the association between the baseline luteinizing hormone/follicle stimulating hormone (LH/FSH) ratio of polycystic ovary syndrome (PCOS) and in vitro fertilisation-embryo transfer outcomes. Methods: This was a retrospective cohort study. A total of 2 868 PCOS patients were enrolled, all of the participants were patients in The First Affiliated Hospital of Anhui Medical University Hospital from October 2015 to October 2021. Propensity score matching (1∶2.5) was conducted to regulate the non-random allocation of patients. Data were extracted from the hospital's medical records. Patients with baseline LH/FSH ratio>2 were deemed as study group, patients with baseline LH/FSH ratio≤2 were deemed as control group. Single factor analysis was applied to compare the differences of pregnancy outcomes between two groups. Results: After propensity score matching (1∶2.5), there were no statistically significant differences in baseline data between the two groups (all P>0.05), indicating that the data were comparable. In the study group, the total dose of gonadotropin (Gn) and duration of Gn were lower than those of the control group (t=4.989, P<0.001; t=3.267, P=0.001), the rate of in vitro maturation was higher than that of the control group (χ²=4.938, P=0.026), the number of retrieved oocytes and cleavage were higher than those of the control group (t=-2.305, P=0.021; t=-2.816, P=0.005), but there were no differences in the number and rate of high-quality embryos between the two groups (t=-1.636, P=0.102; t=-0.123, P=0.902). The incidence of moderate to severe ovarian hyperstimulation syndrome in the study group was significantly higher than that in the control group (χ²=17.277, P<0.001). Regardless of fresh embryo transfer or frozen-thawed embryo transfer cycles, the incidences of gestational diabetes mellitus in the study group were higher than those in the control group (χ²=9.174, P=0.002; χ²=4.204, P=0.040) of singleton pregnancy. In the fresh embryo transfer cycle, the clinical pregnancy rate [30.30% (20/66) vs 47.75% (53/111)] and delivery rate [30.30% (20/66) vs 46.85% (52/111)] in the study group were lower than those in the control group (χ²=5.198, P=0.023; χ²=4.695, P=0.030). In the frozen-thawed embryo transfer cycle, the delivery rate in the study group was higer than that in the control group [59.41% (423/712) vs 55.04% (1 053/1 913); χ²=7.526, P=0.023]. The clinical pregnancy rate and delivery rate of fresh embryo transfer cycle in the study group were significantly lower than those of frozen-thawed embryo transfer cycle (χ²=21.308, P<0.001; χ²=20.871, P<0.001), but there were no significant differences in the control group (all P>0.05). Conclusions: PCOS patients with a higher basal LH/FSH ratio are more likely to develop moderate to severe ovarian hyperstimulation syndrome after controlled ovarian stimulation and have a higher incidence of gestational diabetes mellitus. Better pregnancy outcome could be obtained by frozen-thawed embryo transfer.