# Epidemiology and Associated Factors of Superimposed Preeclampsia in Pregnant Women With Chronic Hypertension: A Retrospective Multicenter Cohort Study

## TL;DR

This study finds that nearly half of pregnant women with chronic hypertension develop superimposed preeclampsia, with high blood pressure and medication use as key risk factors.

## Contribution

The study identifies specific risk factors for superimposed preeclampsia in women with chronic hypertension using a large multicenter cohort.

## Key findings

- Approximately 49% of women with chronic hypertension developed superimposed preeclampsia.
- High mean arterial pressure and use of multiple antihypertensive drugs were strongly associated with increased risk.
- A history of previous preeclampsia also significantly raised the risk of superimposed preeclampsia.

## Abstract

The objective of the study is To to determine the incidence of superimposed preeclampsia among pregnant women with chronic hypertension and associated factors of superimposed preeclampsia:preeclampsia.

A retrospective multicenter cohort study was conducted at Srinagarind Hospital, Khon Kaen University, and Khon Kaen hospitalHospital, Thailand, involving women who were admitted between November 1, 2017, to and October 31, 2022. The pregnant women who had been diagnosed with chronic hypertension were identified and their medical records were reviewed for incidence of superimposed preeclampsia. Various characteristics were examined to compare maternal complications, perinatal outcomes, and associated factors. Logisticfactors.Logistic regression analysis was performed to identify factors associated with superimposed preeclampsia.

There was a total of 33,018 deliveries during the study period, out of which 406 (1.2%) women with chronic hypertension were identified. Superimposed preeclampsia occurred in 199 women, accounting for a rate of 49.0% (95% confidence interval; [CI] 44.1–53.9). One hundred and nineteen women (59.8%) were diagnosed with superimposed preeclampsia with severe features, and 80 (40.2%) without severe features. A mean arterial pressure (MAP) ≥100≥ 100 mmHg during pregnancy, the requirement of two or more antihypertensive agents, and a history of previous preeclampsia were significantly associated with an increased risk of superimposed preeclampsia (adjusted odds ratio; [OR] 9.97, 95% CI95%CI 5.95 – 16.71, adjusted OR 2.31, 95% CI95%CI 1.30 – 4.12, and adjusted OR 4.52, 95% CI95%CI 1.86 – 10.98, respectively).

Approximately half of the women with chronic hypertension developed superimposed preeclampsia. MAP ≥ 100 mmHg, the requirement of two or more antihypertensive agents, and a history of previous preeclampsia might be useful tools for predicting superimposed preeclampsia.