Am J Obstet Gynecol MFM. 2023 Aug 18:101136. doi: 10.1016/j.ajogmf.2023.101136. Online ahead of print.
ABSTRACT
BACKGROUND: Placenta previa diagnosed on midtrimester ultrasound often resolves by the third trimester. Multiparity and prior cesarean delivery have been associated with persistence of placenta previa at delivery. Risk factors for persistent placenta previa in nulliparas are not well characterized.
OBJECTIVES: To identify risk factors for persistent placenta previa in the nulliparous population, as well as evaluate differences in outcomes between persistent and resolved placenta previa.
STUDY DESIGN: This was a secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-be (nuMoM2b), a prospective cohort study that followed 10,037 nulliparous individuals throughout pregnancy. Nulliparas diagnosed with placenta previa on midtrimester ultrasound were included in this analysis. Baseline characteristics and delivery outcomes of nulliparas with persistent placenta previa were compared to those with resolved placenta previa. Multivariate logistic regression with stepwise model selection was used for adjusted analyses.
RESULTS: A total of 171 nulliparas (1.7%) in the nuMoM2b study were diagnosed with placenta previa on midtrimester ultrasound, of whom 17% (n=29) had persistent placenta previa at delivery. When compared to those with resolved placenta previa, nulliparas with persistent placenta previa were more likely to be older (median 32 years (IQR 30-37) vs. 29 years (IQR 25-31), p<0.01), have a prior pregnancy <20 weeks (48.3% vs. 22.5%, p=0.01), have a prior dilation and curettage/evacuation procedure (27.6% vs. 10.6%, p=0.03), or have a pregnancy that resulted from assisted reproductive technology (31% vs. 4.9%, p=0.01). After adjusting for potential confounders, maternal age (aOR 1.11, 95% CI 1.02-1.21), in vitro fertilization (aOR 9.00, 95% CI 1.97-41.14), and prior pregnancy <20 weeks (aOR 2.77, 95% CI 1.10-6.95) remained statistically significant risk factors for persistent placenta previa. Persistent placenta previa also had a higher likelihood of antepartum admission (10.3% vs. 0%, p<0.01), preterm delivery (34.5% vs. 12%, p<0.01), lower neonatal birthweight (median 2847 grams, IQR 2655-3310, vs 3263 grams, IQR 2855-3560) and cesarean delivery (100% vs. 20.4%, p<0.001), but there were no differences in overall pregnancy or neonatal outcomes.
CONCLUSION: In nulliparous individuals diagnosed with placenta previa on midtrimester ultrasound, older maternal age, prior pregnancy <20 weeks, and in vitro fertilization are associated with persistent placenta previa at delivery.
PMID:37598887 | DOI:10.1016/j.ajogmf.2023.101136
