Preeclampsia Drives Maternal Risk in Hypertensive Pregnancy

TOPLINE:

Severe maternal morbidity (SMM) rates are five times higher when preeclampsia develops in pregnancy, regardless of chronic hypertension status. Patients with uncomplicated chronic hypertension who avoid preeclampsia show only marginally higher risk for SMM than those without hypertensive disorders.

METHODOLOGY:

• A retrospective cohort analysis included 263,518 pregnant patients without pregestational heart, kidney, or liver disease entering prenatal care at 14 weeks’ gestation or earlier within a community-based, integrated healthcare system in northern California from 2009 to 2019.
• Researchers categorized participants into five groups: Chronic hypertension with superimposed preeclampsia, chronic hypertension without preeclampsia, no chronic hypertension with preeclampsia, gestational hypertension, and no chronic hypertension without preeclampsia or gestational hypertension.
• Analysis utilized Centers for Disease Control and Prevention criteria to define SMM rates at delivery hospitalization using ≥ 1 of 21 indicators from electronic health records.
• Modified Poisson regression models estimated crude and adjusted relative risks (aRRs) for SMM, controlling for clinical, sociodemographic, social, and behavioral covariates.

TAKEAWAY:

• Among 263,518 pregnant patients, 13,626 had chronic hypertension (5.2%), of whom 31.5% developed superimposed preeclampsia, while 4.7% of 249,892 patients without chronic hypertension developed preeclampsia.
• The highest SMM rates occurred in the no chronic hypertension with preeclampsia (934.3 cases per 10,000 births; 95% CI, 882.3-988.3) and chronic hypertension with superimposed preeclampsia (898.3 cases per 10,000 births; 95% CI, 814.5-987.8) groups.
• Compared with patients without chronic hypertension or preeclampsia, aRRs of SMM were significantly higher for chronic hypertension with superimposed preeclampsia (aRR, 4.97; 95% CI, 4.46-5.54) and no chronic hypertension with preeclampsia (aRR, 5.12; 95% CI, 4.79-5.48) groups.
• Patients with chronic hypertension who did not develop preeclampsia showed only slightly elevated risk (aRR, 1.17; 95% CI, 1.003-1.36; P = .046) compared with those without any hypertensive disorders.

IN PRACTICE:

“This cohort study’s main finding is that preeclampsia accounted for nearly all of the excess risk of severe maternal morbidity associated with chronic hypertension in patients without concurrent preexisting heart, kidney, or liver disease predating pregnancy. For 70% of the patients with chronic hypertension who avoided superimposed preeclampsia, their relative risk of SMM was nearly the same (only 17% higher) as that found in patients without chronic hypertension and no hypertensive disorders developing during pregnancy,” wrote the authors of the study.

SOURCE:

The study was led by Erica P. Gunderson, PhD, MPH, Division of Research, Kaiser Permanente Northern California in Pleasanton, California. It was published online on January 28 in JAMA Network Open.

LIMITATIONS:

Researchers did not evaluate blood pressure levels or control under treatment during pregnancy in patients with or without chronic hypertension that may affect the risk for SMM. Economic deprivation was derived from neighborhood-level data instead of individual-level resources, which may have led to residual or unmeasured confounding differentially affecting the risks for patients with and without chronic hypertension. Additionally, while Kaiser Permanente Northern California members have less representation in the low and high economic strata, membership is representative of the regional diversity.

DISCLOSURES:

The study was funded by grants from the National Heart, Lung, and Blood Institute (grant No. RO1 HL145808 and ROI HL145808-02S1). The sponsor had no role in the design, conduct, analysis, interpretation, manuscript preparation, or publication decision.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.