Effects of pre-pregnancy body mass index on pregnancy and perinatal outcomes in women with PCOS undergoing frozen embryo transfer

BACKGROUND: Previous studies have shown that among women with polycystic ovary syndrome who have difficulties conceiving, frozen-embryo transfer resulted in increased live birth rates and decreased ovarian hyperstimulation syndrome risk than did fresh-embryo transfer. In the present retrospective analysis, we sought to determine the effect of body mass index (BMI) on pregnancy and perinatal outcomes in women with PCOS undergoing FET. METHODS: Women with PCOS (n = 1556) undergoing FET were divided into groups based on weight, with those with normal weight having a BMI of 18.5–24.9 kg/m(2),those who were overweight having a BMI of 25–29.9 kg/m(2), and those who were obese having a BMI ≥30 kg/m(2). Both pregnancy and perinatal outcomes were compared among these groups. RESULTS: The normal-weight, overweight, or obese groups exhibited similar pregnancy outcomes, including clinical pregnancy rate, miscarriage rate, ongoing pregnancy rate and live birth rate. In singletons, birth characteristics regarding newborn gender, gestational age, birthweight and length at birth were comparable between the three groups. For adverse neonatal outcomes, the three groups showed no significant differences on the rates of low birthweight, very low birthweight, preterm birth, and very preterm birth after adjustment. In addition, the obstetric complications and the frequencies of live-birth defects were also comparable between the three groups except that overweight and obese women were more likely than women of normal weight to have delivered via cesarean section. CONCLUSION: BMI did not affect the pregnancy or perinatal outcomes in women with PCOS undergoing FET.