Chronic salpingitis, Vitrified-warmed embryo transfer, Intramuscular progesterone, Inverse probability of treatment weighting, Luteal support, Pregnancy outcomes, Medicine

Abstract Background Chronic salpingitis is one of the most common causes of female infertility. Luteal support is a critical step for embryo transfer. Here, we evaluated the effects of two luteal support regimens, intramuscular progesterone (IMP) and progesterone vaginal gel (VAG), on the pregnancy outcomes in patients with chronic salpingitis undergoing vitrified-warmed embryo transfer. Methods This study retrospectively analyzed 2240 patients with chronic salpingitis undergoing vitrified-warmed embryo transfer from 2015 to 2022 at our center. Patients were categorized into IMP group (n = 1039) and VAG group (n = 1201). Inverse probability of treatment weighting (IPTW) was used to balance baseline characteristics. Univariate and multivariate logistic regression models were conducted to analyze pregnancy outcomes. Results After IPTW, baseline demographic characteristics were balanced and outcome indicators were comparable. Crude analysis showed a higher live birth rate (OR 1.25, 95% CI 1.017–1.537, p = 0.034) and ongoing pregnancy rate (OR 1.231, 95% CI 1.002–1.512, p = 0.047) as well as lower miscarriage rate (OR 0.612, 95% CI 0.461–0.812, p