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Taking into account worrisome blood pressure (BP) patterns by the 20th week of gestation, some women may have a higher risk for hypertensive disorders of pregnancy (HDP) than risk factors alone would suggest, a retrospective study found.

Electronic health records from prenatal outpatient visits at Kaiser Permanente Northern California suggested six early pregnancy systolic BP trajectories from 0 to 20 weeks' gestation: ultra-low declining (100 to 94 mm Hg), low declining (107 to 102 mm Hg), moderate-fast decline (121 to 108 mm Hg), low increasing (110 to 112 mm Hg), moderate stable (120 to 118 mmHg), and elevated stable (129 to 126 mm Hg).

These BP trajectories stratified risk for HDP when modelled atop traditional clinical risk factors, researchers led by Erica Gunderson, PhD, MS, MPH, of Kaiser Permanente Northern California in Oakland, reported in the .

Below, for example, is each BP trajectory's associations with later-onset preeclampsia (≥34 weeks):

• Ultra-low declining: reference
• Low declining: adjusted OR 1.78 (95% CI 1.48-2.15)
• Moderate-fast decline: adjusted OR 2.81 (95% CI 2.32-3.42)
• Low increasing: adjusted OR 3.07 (95% CI 2.55-3.70)
• Moderate stable: adjusted OR 5.14 (95% CI 4.28-6.16)
• Elevated stable: adjusted OR 8.88 (95% CI 7.35-10.73)

Models incorporating these BP trajectories to predict early- and later-onset preeclampsia and gestational hypertension boasted C-statistics ranging from 0.731 to 0.770, which is better than models using only an initial BP measurement plus standard risk factors (0.713-0.744) or the standard risk factors only (0.688-0.695).

"Early and accurate risk stratification is critically important to mitigate serious perinatal morbidity. Thus, a new approach, based on routine clinical BP measurements during the first and early second trimesters (<16–20weeks), holds promise to improve early prediction of HDP by effectively discriminating risk, especially in ostensibly low-to-moderate risk people," Gunderson's group concluded.

HDP are major contributors to maternal and fetal morbidity and mortality. Preeclampsia in particular affects approximately and can lead to seizures and preterm delivery of the baby.

Early-pregnancy screening for preeclampsia (and perhaps soon, all HDP) is currently recommended for risk stratification and potential treatment. High-risk groups include people with chronic hypertension, cardiovascular disease, liver or kidney dysfunction, and diabetes, who may consider taking low-dose aspirin to prevent preeclampsia.

Existing methods to predict HDP have suffered from limited performance and poor real-world implementation, however.

"Predicting [preeclampsia] and [gestational hypertension] in the general population remains highly challenging in clinical practice. Multimarker methods for HDP risk stratification have yet to be widely adopted, partly due to low positive predictive values in low-risk populations, associated costs, lack of standardization, and limited evidence for generalizability," commented William Ackerman IV, MD, and colleagues of University of Illinois College of Medicine-Chicago.

In contrast, "inexpensive and nearly universally available" serial BP measurements would be attractive way to boost HDP screening, they wrote in an .

"Although models such as those developed by Gunderson and colleagues likely require refinement before full implementation, it is reasonable to expect that clinical assessment tools incorporating longitudinal BP measurements will one day be available to help guide personalized decision-making during pregnancy," Ackerman's group suggested.

For their study, Gunderson and colleagues probed records of deliveries from 2009 to 2019 in which the mother started prenatal care at <14 weeks gestation and had BP <140/90 mm Hg or a single BP elevation at ≤20 weeks gestation. Cases of preexisting hypertension, heart, kidney, or liver disease, or prior preeclampsia were excluded.

The resulting cohort of 249,892 individuals was randomly split 70:30 to development and validation groups for the prediction models.

The three highest-risk BP trajectories -- low-increasing, moderate-stable, and elevated-stable -- identified 77% of HDP cases in the internal validation cohort with a specificity of 51%.

Having three or four BP measurements was apparently enough to draw a trajectory for most people.

Gunderson's group acknowledged the study's inability to account for social determinants of health or artificial reproductive technology in relating the six BP trajectories to subsequent HDP. History of preeclampsia may have also been missed in some individuals.

"The current findings by Gunderson and colleagues are provocative. As with any promising area of inquiry, more research is required to determine how robust the presented models might prove to be in practice. External validation cohorts, particularly those comprising racial and ethnic compositions different from those available in this study, are needed to determine the applicability of the models beyond the internal validation group," Ackerman and colleagues said.

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