A Resolved Placenta Previa is Still Associated with Postpartum Hemorrhage

Objective: Our objective was to determine whether resolution of a low-lying placenta or placenta previa is associated with postpartum hemorrhage (PPH). Study Design: This is a retrospective, matched-control cohort study of women who underwent transvaginal sonography during fetal anatomic survey between 18 and 24 weeks of gestation at the University of Pennsylvania from 1/2017-5/2019. Exposure was defined as low-lying placenta (≤1cm from the internal cervical os) or placenta previa (covering the os) at anatomic survey that was found to be resolved by transvaginal ultrasound in the third trimester. For each exposure, we identified a control patient whose placenta was >1cm from internal os at anatomic survey performed on the same day. The primary outcome was PPH at delivery, defined as estimated blood loss >1000 mL. Results: 450 women were included (225/group). The exposed group of resolved placental previa included 85.0% with resolved low-lying placenta and 15.0% with resolved previa. The rate of PPH was significantly higher in the exposed group versus controls (9.8% vs. 4.4%, p=0.03). Women with resolved previa were 2.5 times more likely to experience PPH than controls (aOR 2.58, 95%CI: 1.17-5.69), even when controlling for parity, prior cesarean, and delivery mode. Women with resolved previa were also more likely to present to triage with bleeding (16.4% vs. 8.0%, p=0.006), receive antenatal corticosteroids, (9.3% vs. 3.1%, p=0.006) and receive intravenous iron postpartum (7.6% vs. 3.1%, p=0.04). Conclusion: Our data demonstrate that women with a resolved low-lying placenta or placenta previa remain at significantly increased risk of bleeding-related complications in pregnancy and during delivery when compared to those who never had a previa. Clinicians should consider this association when counseling patients and performing hemorrhage risk stratification.