(1) Background: A cesarean scar defect may cause localized inflammation of the endometrial tissue, and various researchers believe that the presence of a cesarean scar defect is associated with chronic endometritis. However, there is no report on the possible association between cesarean scar defects and chronic endometritis thus far. This study aimed to assess the role of having a cesarean scar defect in a person’s susceptibility to chronic endometritis. (2) Methods: This retrospective propensity-score-matched study comprised 1411 patients with chronic endometritis that were admitted to Henan Provincial People’s Hospital in China from 2020 to 2022. Based on whether a cesarean scar defect was present or not, all cases were assigned to the cesarean scar defect group or the control group. (3) Results: Of the 1411 patients, 331 patients with a cesarean scar defect were matched to 170 controls. All unbalanced covariates between groups were balanced after matching. Before matching, the prevalence of chronic endometritis in the cesarean scar defect group and in the control group was 28.8% and 19.6%, respectively. After correcting for all confounding factors, a logistic regression analysis showed that cesarean scar defect occurrence may increase the risk of chronic endometritis (odds ratio (OR), 1.766; 95% confidence interval (CI), 1.217–2.563; p = 0.003). After matching, the prevalence of chronic endometritis was 28.8% in the cesarean scar defect group and 20.5% in the control group. Thus, even after correcting for all confounding factors, the logistic regression analysis still showed that a cesarean scar defect remained an independent risk factor for chronic endometritis prevalence (OR, 1.571; 95% CI, 1.021–2.418; p = 0.040). The findings were consistent throughout the sensitivity analyses. (4) Conclusions: The present results suggest that the onset of a cesarean scar defect may increase the risk of chronic endometritis.

Background The effect of premature P elevation on assisted reproductive technology outcomes has historically been a matter of some debate. In previous studies, there were conflicting results regarding the impact of elevated progesterone on pregnancy outcomes in different ovarian stimulation protocols, different ovarian response and embryos transferred. In addition, most studies have focused on significantly elevated progesterone levels, such as above 1.5ng/ml, 1.75ng/ml, or even 2ng/ml. However, few studies have focused on slightly elevated progesterone level, and many scholars have previously concluded that it has no adversely effect on pregnancy outcomes. Methods Clinical data of patients were collected who underwent early follicular phase prolonged protocol cycle IVF/ICSI-ET treatment. The women were divided into two groups according to the progesterone level on HCG trigger day : Group 1:<1.0ng/ml; Group 2: 1.0ng/ml-1.5ng/ml. Differences in baseline characteristics, ovulation promotion situation and embryo culture were compared between the two cohorts. After adjusting for confounding factors using multivariate logistic regression analysis, the clinical pregnancy outcomes were compared between the two groups. Results A total of 743 subjects were included in this study, of which 587 were included in Group 1 and 156 were included in Group 2. In terms of pregnancy outcome, Group 2 had a significantly lower clinical pregnancy rate and live birth rate per cycle than Group 1 (64.1% vs 75.7%, P < 0.05; 63.5% vs 72.7%, P < 0.05). After correcting for female BMI, total dose of Gn, days of stimulation, et al using multivariate logistic regression analysis, slightly elevated progesterone levels (P > 1.0ng/ml) remained a risk factor for pregnancy failure in fresh single D5 blastocyst transfer under an early follicular phase prolonged protocol cycle. Conclusion The slightly elevation progesterone level on the HCG trigger day may have a negative effect on the clinical pregnancy in early follicular phase prolonged protocol cycles, even in ETs with a good prognosis.