RÉSUMÉ
OBJECTIVE To explore the effects of letrozole combined with methylprednisolone on clinical outcomes， ovarian reserve function， serum sex hormones， and safety in infertile patients with polycystic ovary syndrome resistant to clomiphene. METHODS The clinical data of 78 infertile patients with polycystic ovary syndrome resistant to clomiphene in the Department of Gynecology of Qingdao Central Hospital from February 2021 to January 2022 was analyzed retrospectively， and all patients were divided into control group （42 cases） and observation group （36 cases） based on the treatment methods. The control group took letrozole 5 mg/d orally on the 5th to 9th day of the menstrual cycle. Vaginal ultrasound was used to monitor the development of the endometrium and follicles； estradiol valerate was used to correct endometrial thickness， and measures such as inducing ovulation with follicle-stimulating hormone were taken to promote pregnancy. On the basis of treatment in the control group， the observation group began taking methylprednisolone orally at a dose of 4 mg/d starting from the third day of natural menstruation or withdrawal bleeding. Both groups were treated for 6 menstrual cycles. The ovulation and pregnancy within one year， serum levels of sex hormones [estradiol （E2）， luteinizing hormone （LH）， follicle-stimulating hormone （FSH）， testosterone] and anti-Müllerian hormone （AMH）， ovulation indicators （follicle growth time， the number of ovulations， and the number of dominant follicles）， and the occurrence of adverse drug reactions were compared between the two groups. RESULTS After treatment， the biochemical pregnancy rate （72.22%） and clinical pregnancy rate （47.22%） of the observation group were significantly higher than those of control group （47.62%， 19.05%）； the serum levels of E2， LH， FSH， testosterone and AMH were significantly lower than the control group； the follicle growth time was significantly shorter than the control group； the number of ovulation and dominant follicles were significantly higher than the control group （P＜0.05）. There was no statistically significant difference in ovulation rate （94.44% vs. 83.33%） and total incidence of adverse drug reactions （8.33% vs. 9.52%） between the observation group and the control group （P＞0.05）. CONCLUSIONS Compared with letrozole alone， the combination of letrozole and methylprednisolone can significantly improve the pregnancy rate， the sex hormone levels and ovarian reserve function in infertile patients with polycystic ovary syndrome resistant to clomiphene， with high safety profiles.