Effects of letrozole alone or in combination with gonadotropins on ovulation induction and clinical pregnancy in women with polycystic ovarian syndrome: a systematic review and meta-analysis of randomized controlled trials

Objective To compare letrozole in combination with gonadotropins versus letrozole monotherapy in ovulation induction and clinical pregnancy among infertile women with polycystic ovarian syndrome (PCOS). Methods Several databases were searched for available clinical trials from inception until March 2023. We selected randomized controlled trials (RCTs) that compared sequential letrozole/gonadotropin versus letrozole alone among infertile women who met the Rotterdam criteria for PCOS. RevMan software was used to perform our meta-analysis. Our primary outcomes were ovulation and clinical pregnancy rates. Our secondary outcomes were endometrial thickness, number of mature follicles (diameter >= 18 mm), and incidence of miscarriage and ovarian hyperstimulation syndrome (OHSS). Results Six RCTs were retrieved with a total number of 723 patients. The ovulation and clinical pregnancy rates were significantly higher among the letrozole/gonadotropin group versus the letrozole monotherapy group (p < 0.001). In addition, there were significant improvements in endometrial thickness and number of mature follicles in the letrozole/gonadotropin group. There were no significant differences between the two groups regarding incidence of miscarriage and ovarian hyperstimulation syndrome. Conclusion Letrozole in combination with gonadotropin is superior to letrozole alone in improving ovulation induction and clinical pregnancy among PCOS patients. More trials are required to confirm our findings.