Correlation Between Chronic Endometritis and Early Pregnancy Loss: a prospective cohort study

Background Early Pregnancy Loss (EPL) refers to embryonic loss occurring before 10 weeks of gestation, including biochemical pregnancy. Chronic Endometritis is a chronic inflammation of the endometrial lining. The association between chronic endometritis and early pregnancy loss remains controversial, with inconsistent findings and insufficient evidence from existing studies. Therefore, this study was conducted to address this research gap. Methods This prospective cohort study enrolled 1,059 patients with definitive pregnancy outcomes completed the study from December 2020 to December 2024. Using independent samples t-test, analysis of variance (ANOVA), and chi-square test were used to compare differences between groups, while logistic regression analysis was applied to explore the association between CE and EPL. Results The prevalence of CE among patients with pregnancy loss was 39.8% (431/1,059). The incidence of early pregnancy loss was 10.05% in the non-CE group and 28.07% in the CE group. With the increase in CE severity, the incidence of EPL gradually increased: 15.82% in the mild CE group, 22.58% in the moderate CE group, and 33.94% in the severe CE group, with a statistically significant difference between groups (P < 0.001). Multivariate logistic regression analysis showed that CE was an independent risk factor for EPL. After adjustment, patients with CE had a 37% increased risk of EPL (odds ratio OR = 1.37, 95% CI: 1.14–1.67, P = 0.003). Subgroup analysis revealed that the association between CE and EPL was more pronounced in patients aged ≥ 30 years and those with ≥ 3 previous pregnancy losses. Conclusion Chronic endometritis has a high prevalence among patients with pregnancy loss, and its severity is an independent risk factor for subsequent early pregnancy loss. The impact of CE on EPL is more significant in subgroups of older patients and those with multiple previous pregnancy losses. Clinically, screening for CE and assessment of its severity should be performed in patients with pregnancy loss, especially in high-risk subgroups, to optimize pregnancy outcomes. Trial registration This study was registered in the Chinese Clinical Trial Registry with the registration number of ChiCTR2000039414 (27/10/2020)