Beyond Conception: Does Preconception Treatment of Endometriosis Improve Obstetric and Perinatal Outcomes? A Systematic Review and Meta-analysis

Abstract Background: Endometriosis is associated with adverse obstetric outcomes, most consistently placenta previa, but whether treating it before conception changes these risks is unknown. We assessed whether preconception surgical or medical treatment of endometriosis alters obstetric, perinatal and early-pregnancy outcomes in women who subsequently conceive. Methods: PubMed/MEDLINE, Scopus, the Cochrane Central Register of Controlled Trials and two trial registers were searched to 31 August 2026 without language restriction. Randomized trials and comparative observational studies comparing pregnancy outcomes by preconception treatment status were eligible. Risk of bias was assessed with RoB 2 and ROBINS-I. Unadjusted odds ratios (ORs) were pooled by random-effects meta-analysis within distinct treatment contrasts and endometriosis phenotypes, and certainty was graded with GRADE. Results: Of 125 full-text reports sought, 30 could not be retrieved. Twenty studies (nine randomized trials) were included, and 14 contributed to meta-analyses. All late-pregnancy evidence was non-randomized. Placenta previa odds were lower after endometrioma surgery (one study; OR 0.30, 95% confidence interval 0.12–0.76) and higher in mixed-phenotype cohorts (two studies; OR 1.87, 1.37–2.54) and after deep-endometriosis surgery (two studies; OR 3.57, 0.51–25.09), but the phenotype difference was not robust (meta-regression p = 0.13). Surgery was not associated with preterm birth (four studies; OR 0.91, 0.46–1.80) or pre-eclampsia (OR 1.00, 0.77–1.32) but was associated with postpartum hemorrhage (three studies; OR 1.87, 1.60–2.19) and cesarean delivery (six studies; OR 1.52, 1.36–1.69). Among women who conceived, miscarriage was less frequent after surgery (five studies; OR 0.63, 0.41–0.97) but not in randomized trials of surgery (OR 0.85, 0.34–2.15) or of medical pretreatment before in vitro fertilization (two trials; OR 1.65, 0.60–4.57). Non-randomized studies were at serious risk of bias from confounding by indication, and certainty was very low for all outcomes. Conclusions: Preconception treatment of endometriosis has not been shown to reduce adverse obstetric or perinatal outcomes. Postpartum hemorrhage, cesarean delivery and possibly placenta previa are more frequent after surgery, plausibly reflecting more severe disease in operated women. Treatment should be offered for pain and fertility, and women with treated endometriosis, especially deep disease, should be managed as having higher-risk pregnancies.