Effects of body mass index on the outcomes of in vitro fertilization in Chinese patients with polycystic ovary syndrome: a retrospective cohort study*

Objective: To investigate the effects of body mass index (BMI) on the outcomes of in vitro fertilization (IVF) in Chinese patients with polycystic ovary syndrome (PCOS). Methods: In the retrospective cohort study, a total of 1074 patients with PCOS undergoing IVF between April 2010 and May 2017 in two reproductive medicine centers, respectively in eastern China (Women’s Hospital, School of Medicine, Zhejiang University, Zhejiang Province) and in southern China (Maternal and Child Health Care Hospital of Liuzhou, Guangxi Province), were included. The patients were divided into four groups according to the recommended Chinese BMI cut-off points: underweight (BMI<18.5 kg/m2), normal weight (18.5 kg/m2≤BMI<24.0 kg/m2), overweight (24.0 kg/m2≤BMI<28.0 kg/m2), and obese (BMI≥28.0 kg/m2). The basic characteristics of the PCOS patients, the details of IVF treatment, and the pregnancy outcomes were collected. Main results: There were no significant differences among the normal weight, overweight, and obese PCOS patients undergoing IVF on the biochemical pregnancy rate, clinical pregnancy rate, miscarriage rate, live birth rate, or term delivery rate (P>0.05), although the overweight and obese PCOS patients required more gonadotropin (Gn) (P<0.001) as well as longer stimulation period (P<0.001), and got less retrieved oocytes (P<0.05) and fertilized oocytes (P<0.05). The underweight PCOS patients required less Gn (P<0.05) and achieved higher live birth rate and term delivery rate (P<0.05), compared with the normal weight PCOS patients. Conclusions: High BMI had no negative effects on the outcomes of IVF in Chinese patients with PCOS; however, the conclusion may seem a little limited due to the retrospective design and the potential bias.