The Association of Endometriosis and Placenta Previa During Pregnancy [A137]

INTRODUCTION: Endometriosis is a common gynecological disease characterized by chronic inflammation, with an estimated prevalence of approximately 5% to 15%. The prevalence of endometriosis has been increasing in reproductive-aged women, but recent developments in assisted reproductive technologies have improved pregnancy rates among women with endometriosis. METHODS: This study aimed to assess the relationship between placenta previa and endometriosis. In compliance with the Preferred Reporting Items for Systematic Reviews guidelines, a systematic review of the literature was conducted through June 30, 2021, using PubMed, Scopus, and the Cochrane Library. RESULTS: Twenty-three studies in which 99,773 pregnancies with endometriosis and 7,184,426 pregnancies without endometriosis were systematically reviewed. Using an adjusted-pooled random effects analysis, we found that endometriosis was associated with an increased incidence of placenta previa (adjusted odds ratio [aOR], 3.17; 95% CI, 2.58–3.89) compared to those without endometriosis. We also performed an unadjusted analysis using a fixed effects model and found that severe endometriosis was associated with an increased prevalence of placenta previa (OR, 11.86; 95% CI, 4.32–32.57), whereas non-severe endometriosis was not (OR, 2.16; 95% CI, 0.95–4.89). Notably, one study showed that placenta previa with endometriosis was associated with increased intraoperative bleeding (1,515 mL versus 870 mL, P<.01) compared to those without endometriosis. CONCLUSION: There is a strong association between endometriosis and an increased rate of placenta previa, and endometriosis may be associated with adverse surgical outcomes during cesarean delivery. Therefore, the development of novel therapeutic agents or methods are warranted to prevent placenta previa in women with endometriosis.