{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,30]],"date-time":"2026-01-30T07:57:09Z","timestamp":1769759829782,"version":"3.49.0"},"reference-count":30,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2025,3,3]],"date-time":"2025-03-03T00:00:00Z","timestamp":1740960000000},"content-version":"vor","delay-in-days":2,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["American J Rep Immunol"],"published-print":{"date-parts":[[2025,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Problem<\/jats:title><jats:p>The relationship between abortion and endometriosis (EMS) has been inconsistent in previous observational studies and remains controversial. We intended to examine the causal relationship between abortion and EMS.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods of Study<\/jats:title><jats:p>We conducted a Mendelian randomization (MR) analysis using genome\u2010wide association study (GWAS) summary statistics, drawing data from the FinnGen database and the UK Biobank. The primary analysis utilized the random\u2010effects inverse variance weighted (IVW) approach, complemented by weighted median, weighted mode, and MR\u2013Egger methods. Comprehensive sensitivity analyses were conducted, encompassing the Cochran's <jats:italic>Q<\/jats:italic> statistic for assessing heterogeneity and MR\u2010PRESSO to detect pleiotropy. Additionally, Leave\u2010One\u2010Out (LOO) analysis was conducted to confirm the stability of our results.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The IVW method revealed no statistically significant causal association between various types of abortion and EMS. Specifically, the odds ratios (ORs) were as follows: medical abortion (OR 0.96, 95% CI: 0.78\u20131.18, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.72), spontaneous abortion (OR 0.99, 95% CI: 0.81\u20131.21, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.92), and other types of abortions (OR 1.01, 95% CI: 0.99\u20131.03, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.36), indicating no significant effects on the risk of EMS. Similarly, analysis in the reverse direction showed no significant causal effects of EMS on the likelihood of experiencing any type of abortion, with ORs for medical abortion (0.97, 95% CI: 0.91\u20131.03, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.33), spontaneous abortion (0.98, 95% CI: 0.92\u20131.04, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.50), and other abortions (1.30, 95% CI: 0.76\u20132.23, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.34). Sensitivity analyses supported these findings, demonstrating no evidence of horizontal pleiotropy or significant heterogeneity.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Our MR results do not support a causal relationship between abortion and EMS.<\/jats:p><\/jats:sec>","DOI":"10.1111\/aji.70064","type":"journal-article","created":{"date-parts":[[2025,3,11]],"date-time":"2025-03-11T13:42:43Z","timestamp":1741700563000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Causal Relationship Between Abortion and Endometriosis: A Bidirectional Two\u2010Sample Mendelian Randomization Study"],"prefix":"10.1111","volume":"93","author":[{"given":"Yan","family":"Huang","sequence":"first","affiliation":[{"name":"Department of Gynecology and Obstetrics Peking University First Hospital  Beijing 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