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.

Objective:To analyze the risk factors of bronchopulmonary dysplasia(BPD)in very preterm infants(VPI), and to provide scientific basis for the prevention and treatment of BPD in VPI.Methods:A prospective multicenter study was designed to collect the clinical data of VPI in department of neonatology of 28 hospitals in 7 regions from September 2019 to December 2020.According to the continuous oxygen dependence at 28 days after birth, VPI were divided into non BPD group and BPD group, and the risk factors of BPD in VPI were analyzed.Results:A total of 2 514 cases of VPI including 1 364 cases without BPD and 1 150 cases with BPD were enrolled.The incidence of BPD was 45.7%.The smaller the gestational age and weight, the higher the incidence of BPD( P<0.001). Compared with non BPD group, the average birth age, weight and cesarean section rate in BPD group were lower, and the incidence of male infants, small for gestational age and 5-minute apgar score≤7 were higher( P<0.01). In BPD group, the incidences of neonatal respiratory distress syndrome(NRDS), hemodynamically significant patent ductus arteriosus, retinopathy of prematurity, feeding intolerance, extrauterine growth restriction, grade Ⅲ~Ⅳ intracranial hemorrhage, anemia, early-onset and late-onset sepsis, nosocomial infection, parenteral nutrition-associated cholestasis were higher( P<0.05), the use of pulmonary surfactant(PS), postnatal hormone exposure, anemia and blood transfusion were also higher, and the time of invasive and non-invasive mechanical ventilation, oxygen use and total hospital stay were longer( P<0.001). The time of starting enteral nutrition, cumulative fasting days, days of reaching total enteral nutrition, days of continuous parenteral nutrition, days of reaching 110 kcal/(kg·d) total calorie, days of reaching 110 kcal/(kg·d) oral calorie were longer and the breastfeeding rate was lower in BPD group than those in non BPD group( P<0.001). The cumulative doses of amino acid and fat emulsion during the first week of hospitalization were higher in BPD group( P<0.001). Multivariate Logistic regression analysis showed that NRDS, invasive mechanical ventilation, age of reaching total enteral nutrition, anemia and blood transfusion were the independent risk factors for BPD in VPI, and older gestational age was the protective factor for BPD. Conclusion:Strengthening perinatal management, avoiding premature delivery and severe NRDS, shortening the time of invasive mechanical ventilation, paying attention to enteral nutrition management, reaching whole intestinal feeding as soon as possible, and strictly mastering the indications of blood transfusion are very important to reduce the incidence of BPD in VPI.