Potential resolution of placenta previa from the 28th-to the 36th-week of pregnancy: A retrospective longitudinal cohort study

Placenta previa greatly contributes to severe antenatal and post-partum hemorrhage. Previous studies have mainly focused on the risk factors of placenta previa, with very few studies reporting which factors may affect the potential resolution of 28th-week previa. This study aimed to investigate the impact of maternal characteristics on potential resolution of placenta previa from the 28th-to the 36th-week of pregnancy.A retrospective longitudinal sub-cohort investigation was carried out among 368 pregnant women with 28th-week previa from the Longitudinal Placenta Previa Study (LoPPS). Logistic regression analysis was used to discover the connections between maternal covariates and the placental potential resolution. Multivariable linear regression analysis was used to detect the associations between perioperative characteristics and volume of intraoperative bleeding.Among pregnant women whose placenta completely or partially covered the internal os at the 28th-week of pregnancy, 37.5% were without placenta previa at the 36th-week and 25.8% converted into marginal placenta previa. There were significant correlation between placenta previa type and GHD (Beta: 2.808, 95% CI: 1.642, 7.138; p = 0.041), type of 28th-week previa (Beta: 6.767, 95% CI: 1.592, 18.767; p 0.001), and number of prior cesarean sections (Beta: 3.326, 95% CI: 1.580, 9.081; p 0.001).62.5% of the pregnant women with 28th-week placenta previa were still with previa at the 36 weeks of gestation (25.8% with marginal and 36.7% with partial/complete placenta previa). This proportion is even higher for 28th-week complete placenta previa.Chinese Clinical Trial Registry ChiCTR2100054068, December 8, 2021.