Letrozole yields superior pregnancy outcomes and safety profile compared with clomiphene citrate in intrauterine insemination cycles: a propensity score matching analysis.

OBJECTIVE

By using the propensity score matching (PSM) method, this study compared the pregnancy outcomes of two ovulation induction regimens, clomiphene citrate (CC) and letrozole (LE), in intrauterine insemination (IUI) cycles. It aimed to evaluate the impact of these regimens on the clinical pregnancy rate, live birth rate, safety, and cost-effectiveness.

METHODS

Patients who underwent IUI with CC or LE monotherapy for ovulation induction from May 2024 to August 2025 were included. Baseline data and ovulation induction-associated parameters were retrieved from the electronic medical record system, and confounders were balanced by PSM. The clinical pregnancy rate and live birth rate served as the primary outcome measures of this study, while the biochemical pregnancy rate, implantation rate, OHSS incidence, multifetal gestation rate, and treatment cost constituted the secondary measures.

RESULTS

216 patients (108 each in the CC and LE groups) were included. Higher clinical pregnancy and live birth rates were confirmed in the LE group compared to the CC group (P<0.05). In the LE group, the first-trimester pregnancy rate and the second-trimester pregnancy continuation rate were superior (P<0.05). Concerning the implantation rate, the singleton pregnancy rate was higher and the multifetal gestation rate was lower in the LE group (P<0.05). The LE group also performed better in terms of Estradiol (E2) levels on the day of human chorionic gonadotropin (HCG) administration, with an elevated percentage of type A endometrium (P<0.05).

CONCLUSIONS

LE shows higher pregnancy efficiency, better endometrial receptivity, and lower risk of multifetal gestation in IUI cycles.