Appendectomy During Pregnancy and the Risk of Preterm Birth: A Systematic Review of Contemporary Clinical Studies

Background and Objectives: Appendectomy is the most frequent non-obstetric emergency operation in pregnancy, yet its relationship with preterm birth (PTB) remains uncertain. We systematically reviewed studies assessing PTB after appendectomy during pregnancy, focusing on surgical approach and histopathology. Methods: Following a PRISMA-guided protocol, we searched PubMed, Scopus, and Web of Science to 1 October 2025 for studies reporting gestational-age outcomes after appendectomy in pregnancy. Eligible designs were cohort or case-control studies and case series ≥ 5 pregnancies. Data on technique, timing, pathology, and PTB were extracted and synthesized narratively; meta-analysis was not performed because of heterogeneity. Results: Six studies including over one thousand pregnancies with appendectomy and over one million comparators were identified. In the largest registry study, appendectomy was associated with increased PTB risk (adjusted hazard ratio [aHR] 1.73, 95% CI 1.42-2.09), with a stronger association for planned than spontaneous PTB. A matched cohort reported PTB in 11.9% of operated women versus 5.4% of controls and a higher PTB rate after negative appendectomy (20.5% vs. 9.2% with inflamed appendices). In a single-center series, PTB occurred in 24.4% after open but 0% after laparoscopic appendectomy. Across studies, crude PTB rates after appendectomy ranged from 4.5% to 24.4%. Three of five studies reporting effect estimates found significantly elevated PTB risk, whereas two smaller cohorts showed null or imprecise associations. Conclusions: Current evidence suggests that appendectomy in pregnancy is associated with increased PTB risk, particularly after negative or late-gestation open procedures, supporting careful diagnostic work-up, preference for laparoscopy when feasible, and close obstetric follow-up.