Patients with resolution of low‐lying placenta and placenta previa remain at increased risk of postpartum hemorrhage

ABSTRACT Objective To determine whether women who experience resolution of low placentation (low‐lying placenta or placenta previa) are at increased risk of postpartum hemorrhage compared to those with normal placentation throughout pregnancy. Methods This was a retrospective cohort study of women who delivered at Mount Sinai Hospital between 2015 and 2019, and who were diagnosed with low‐lying placenta or placenta previa on transvaginal ultrasound at the time of the second‐trimester anatomical survey, with resolution of low placentation on subsequent ultrasound examination. Women undergoing second‐trimester anatomical survey who had normal placentation on transvaginal ultrasound 3 days before or after the cases were randomly identified for comparison. The primary outcome was the rate of postpartum hemorrhage. Secondary outcomes included the need for a blood transfusion, use of additional uterotonic medication, the need for additional procedures to control bleeding, and maternal admission to the intensive care unit. Outcomes were assessed using a multivariable logistic regression model. Results A total of 1256 women were identified for analysis, of whom 628 had resolved low placentation and 628 had normal placentation. Women with resolved low placentation, compared to those with normal placentation throughout pregnancy, had significantly higher mean age (33.0 ± 5.4 years vs 31.9 ± 5.5 years; P