Individuals with a history of Cesarean or Induced abortion combined with allergies will significantly increase their risk of endometriosis: A prospective case-control study

Abstract

Objective: To investigate the association between delivery/abortion methods, allergy history, and endometriosis (EM) risk.

Methodology: This prospective case-control study was conducted at the First Affiliated Hospital of Naval Medical University (Shanghai Changhai Hospital), China, from 2018 to 2024. We enrolled 1498 EM patients and 452 non-EM controls. Associations between clinical variables (delivery modes, abortion, allergy history) and EM incidence were analyzed using multivariate logistic regression to adjust for confounders.

Results: Cesarean section increased EM risk approximately 2-fold (OR 2.043, 95% CI: 1.489-2.804); this risk remained significant after excluding scar EM (OR 1.944, 95% CI: 1.414-2.674). Induced abortion also correlated with a 2-fold increased risk of EM (OR 2.262, 95% CI: 1.529-3.347). Furthermore, allergic patients with a history of induced abortion had a significantly higher likelihood of developing deep infiltrating endometriosis (DIE).

Conclusion: Cesarean section and induced abortion independently increase EM risk. Moreover, induced abortion combined with an allergy history elevates the risk of developing DIE, highlighting the synergistic effect of surgical trauma and immune status on EM pathogenesis.