(838) Is placenta accreta spectrum inversely associated with hypertensive disorders of pregnancy?

Friday, February 10, 2023

10:30 AM – 12:00 PM

Objective: Placenta accreta spectrum (PAS) is characterized by abnormal trophoblast activity and vascular remodeling that is theorized to be the pathophysiological opposite of hypertensive disorders of pregnancy (HDP). The resulting clinical manifestations are states of relative placental hyper-perfusion with PAS (neovascularity, hemorrhage) and hypo-perfusion with HDP (growth restriction, SGA). Small studies suggest that PAS may be protective for HDP, but they did not account for known differences in the gestational age (GA) at which PAS is typically delivered (i.e. censoring). We aimed to evaluate the association between PAS and HDP in a large, population-based cohort, accounting for GA differences.

Study Design: We performed a retrospective cohort study using the U.S. National Inpatient Sample (NIS) from 2017-2019 including pregnancies ≥20 weeks’ gestation. ICD-10 codes were used to determine exposure, outcomes, and gestational age (GA). Incidence rate ratios (IRR) were calculated to account for time at risk since the risk of HDP accumulates throughout pregnancy. Strata homogeneity was tested with A Mantel–Haenszel (M-H) statistic. Separately, a Poisson regression model controlling for confounding variables (Figure legend) was constructed. Data were weighted according to NIS reported weights to provide national estimates.

Results: Of 10,754,244 (2,150,850 unweighted) individuals included, 0.12% had PAS and 11.9% had HDP. Baseline characteristics were similar in the PAS and non-PAS groups (Table). The association of PAS with HDP significantly differed by gestational age (M-H p < 0.001), with PAS associated with a lower risk of HDP in the < 34 and 34-37 weeks’ strata, and a higher risk of HDP at term. (Figure). When controlling for confounders, HDP occurred at a lower rate in individuals with PAS than without PAS (IRR 0.65; 95% CI 0.59-0.72).

Conclusion: In this large, nationally representative cohort, individuals with PAS had 35% reduced incidence of HDP. Differing associations by GA may represent misclassification of PAS at term and require further investigation.

Primary & Presenting Author(s)

Matthew B. Givens, MD (he/him/his)
Fellow Physician
University of Utah
Salt Lake City, Utah, United States

Coauthor(s)

Michelle P. Debbink, MD, PhD
Assistant Professor
University of Utah Health
Salt Lake City, Utah, United States
Lauren H. Theilen, MD, MSCI
Assistant Professor
University of Utah Health
Salt Lake City, Utah, United States
AA
Amanda A. Allshouse, MS
Perinatal Biostatistician
University of Utah
Salt Lake City, Utah, United States
Nathan R. Blue, MD
Assistant Professor
Department of OBGyn, University of Utah Health
Salt Lake City, Utah, United States
BS
Bob M. Silver, MD
Chair OB/GYN
Univ. of Utah School of Medicine
Salt Lake City, Utah, United States
Brett D. Einerson, MD, MPH (he/him/his)
Assistant Professor, Director of The Utah Placenta Accreta Program
University of Utah Health
Salt Lake City, Utah, United States