Objective To evaluate the effect of polycystic ovary syndrome (PCOS) without hyperandrogenism on pregnancy-related outcomes. Design A retrospective cohort study. Setting Reproductive Medicine Centre of Tongji Hospital. Population Women without hyperandrogenism undergoing their first single blastocyst transfers in frozen-thawed cycles were divided into a PCOS group and a non-PCOS group according to the Rotterdam criteria. Methods The pregnancy-related outcomes of women with and without PCOS were compared. Propensity score matching and multiple logistic regression models were used to eliminate essential impacts on pregnancy-related outcomes. Main outcome measures Pregnancy-related outcomes included pregnancy loss and abnormal perinatal outcomes. Results A total of 4083 women without hyperandrogenism met the study criteria, among whom 557 met the diagnostic criteria for PCOS. Women with PCOS had higher rates of clinical pregnancy (P = 0.035) and cumulative live births (P = 0.023). However, there were no significant differences in the rates of biochemical pregnancy, twins and pregnancy loss between the two groups. Among women with singleton pregnancies, the incidences of preterm birth, hypertensive disorders of pregnancy, gestational diabetes, placenta praevia, fetal malformation, macrosomia and low birthweight did not differ significantly between the two groups. The results remained unchanged even after adjustments were made for propensity score matching and multiple logistic regression analyses. Conclusion Women with PCOS without hyperandrogenism may achieve higher rates of clinical pregnancy and cumulative live birth than those without PCOS, without increases in their rates of biochemical pregnancy, pregnancy loss or other abnormal perinatal outcomes. Tweetable abstract PCOS without hyperandrogenism was not associated with abnormal pregnancy-related outcomes.