(392) Prior Delivery History and Risk of Placenta Accreta Spectrum

Thursday, January 30, 2025

4:00 PM – 6:00 PM

Submitting Author and Presenting Author(s)

Alesha M. White, MD (she/her/hers)

Fellow
University of Texas Southwestern Medical Center
Dallas, Texas, United States

Coauthor(s)

AW

Ariana Weiss

University of Texas Southwestern Medical Center
Dallas, Texas, United States
JP

Jessica E. Pruszynski, PhD

University of Texas Southwestern
Dallas, Texas, United States
Christina L. Herrera, MD

Assistant Professor
University of Texas Southwestern Medical Center
Dallas, Texas, United States

Objective: Previous cesarean delivery, prior uterine procedures, in vitro fertilization and placenta previa are known risk factors for placenta accreta spectrum (PAS). Further studies investigating prior delivery characteristics and risk of PAS are limited. The objective of this study was to describe additional risk factors in prior deliveries associated with the development of PAS.

Study Design: This was a case-control study at a single institution from June 2009 through June 2022 that included patients with prenatal suspicion of PAS based on imaging and confirmed at the time of delivery. Cases were matched to controls based on age, race, number of cesarean deliveries and prior vaginal birth. Prior delivery characteristics included preterm prelabor rupture of membranes, preterm birth, chorioamnionitis, delivery stage, uterine incision, bladder flap closure, peritoneal closure and manual placental extraction. Location of placenta in relation to the internal os on second trimester sonogram in the prior pregnancy was also analyzed. A conditional logistic regression model was used, that accounted for 3:1 matching, to compare cases to controls. A p-value less than 0.05 was significant.

Results: 55 cases were matched to 165 controls. There were no differences in maternal characteristics or comorbidities. Cases were more likely to have experienced preterm birth (OR 3.00 95% CI 1.37-6.57) and have had a manual placenta extraction (OR 5.25 95% CI 1.54-17.93) in a prior delivery. Placental location in a prior pregnancy was not significantly different between cases and controls (Table).

Conclusion: Preterm birth and manual extraction of the placenta in a prior pregnancy appear to be additional risk factors for development of PAS in future pregnancies. Further multicentered studies with a larger population are needed to further understand other risk factors for PAS.