Six routine blood pressure (BP) patterns recorded in the first half of pregnancy—when used in conjunction with other risk factors—may be able to determine risk of preeclampsia and gestational hypertension in low- to moderate-risk patients, suggests a new study just released in the Journal of the American Heart Association.

The 6 distinct BP patterns seen within the first 20 weeks of pregnancy —both initial levels and changes in patterns over time—can be used along with clinical, social, and behavioral risk factors to accurately predict and stratify patients by their risk of developing preeclampsia and gestational hypertension later in pregnancy.

Pregnant women at higher risk for preeclampsia are typically followed more closely by their doctors and may also be administered low-dose aspirin to treat the condition.  These new findings suggests that BP trajectory groups may improve risk stratification and help health care providers identify patients who don’t appear to be at high risk in the first half of their pregnancy—but actually are.

The prediction models accurately classified the patients with an increased risk for developing preeclampsia and gestational hypertension based on early BP patterns several months before the onset of disease.  Three of the early pregnancy BP trajectories identified 74% of the patients who went on to develop preeclampsia later in their pregnancy.  Importantly, the prediction model worked equally well in the white, Black, Hispanic, and Asian patients included in the study.

Nationally, hypertensive diseases of pregnancy are major contributors to maternal and fetal morbidity and mortality.  Preeclampsia alone currently impacts approximately 1 in 25 pregnancies in the US and can lead to seizures and preterm delivery of the baby.

Data on ~75,000 women

The research team from Kaiser Permanente analyzed BP measurements and other data from the electronic medical records of approximately 250,000 healthy pregnant patients who gave birth to one child during a single pregnancy at a Kaiser Permanente Northern California hospital between 2009 and 2019.  All of the women were considered to be at low-to-moderate risk of developing hypertensive disorders of pregnancy based on US Preventive Services Task Force criteria—a group for whom it has been challenging to identify individual risk of preeclampsia.  Patients with high-risk conditions, such as prior chronic hypertension, liver disease, or kidney disease, were excluded from the analysis.

In a previous study, the research team had identified the 6 distinct BP trajectories in a subset of about 175,000 of the patients.  The new study applied the 6 BP trajectories to data from approximately 75,000 women not included in the prior study.

In the just published study, approximately 1 in 10 study subjects developed hypertensive disorders of pregnancy after 20 weeks:  0.4% developed early-onset preeclampsia (before 34 weeks of pregnancy), 4.3% developed later-onset preeclampsia, and 4.6% developed gestational hypertension.

Three of the 6 BP trajectories observed in the first 20 weeks of pregnancy were able to identify nearly 3 in 4 patients (74%) who subsequently developed preeclampsia in the latter half of their pregnancy as well as 82% of gestational hypertension outcomes in more than half (52%) of the study group.

The absolute observed risk of preeclampsia ranged from 0.5% to over 15%, while risk of gestational hypertension ranged from 0.4% to 17.6% based on race, ethnicity, nulliparity, and maternal obesity, among other factors.

More at-risk than realized

The findings suggest that even within populations of patients considered to be at low-to-moderate risk, there are subsets of patients at higher risk, including those with common risk factors such as nulliparity and obesity.

“The prediction models accurately classified the patients with an increased risk for developing preeclampsia and gestational hypertension based on early blood pressure patterns several months before the onset of disease,” stated lead author Erica P. Gunderson, PhD, MPH, a senior research scientist at the Kaiser Permanente Division of Research and a professor at the Kaiser Permanente Bernard J. Tyson School of Medicine.

“During a healthy pregnancy, blood pressure declines during the first half of pregnancy,” said Gunderson.  “Our study found that patients who had moderately higher systolic blood pressure at the start of their pregnancy that didn’t decline as expected or had a normal blood pressure that increased through mid-pregnancy had the higher risk of developing early-onset or later-onset preeclampsia in the second half of pregnancy.”

Inexpensive precision care

The research team underscored the value of the feasibility which BP measurement represents to implement a risk stratification program given it is a tool which requires neither costly biomarker testing nor biophysical parameters.

“The use of a simple measure, blood pressure, that is available as part of clinical care to fine tune clinical risk assessment and identify those at highest risk could allow modification of care and the use of preventive therapies to the most appropriate patients,” stated co-author James M. Roberts, MD, a professor of obstetrics, gynecology, and reproductive science at the University of Pittsburgh.

“These findings are likely to influence practice standards.  Current guidelines recommend that patients with only one moderate risk factor are to be ‘considered’ for treatment with [low-dose aspirin administration],” highlighted the researchers.

“The systolic [blood pressure trajectory] patterns based on 3 or 4 BP measurements in the first half of pregnancy reclassified a substantial proportion of patients considered as moderate risk under current guidelines’ criteria as having lower risk for preeclampsia and gestational hypertension,” they continued.

“The effectiveness of the early pregnancy [blood pressure trajectory] patterns to discriminate high-risk individuals within an ostensibly low-to-moderate risk population is a major advancement in precision care without expensive assessments.”

By incorporating blood pressure readings into clinical risk assessment, healthcare professionals can more accurately identify individuals who are at the highest risk.  This could then enable care plans to be customized to the patient with preventive therapies specifically tailored to those who would benefit the most from them.

Next, the researchers plan to create an automated tool that can be integrated into the EHR.  This tool will have the capability to identify patients in real time by analyzing their BP patterns prior to 16 to 20 weeks of pregnancy.  Once identified, healthcare providers can promptly inform these patients about their elevated risk for hypertensive disorders of pregnancy.  Additionally, they can offer suitable interventions and provide enhanced monitoring to effectively manage and mitigate potential complications.

The full paper, “Early Pregnancy Systolic Blood Pressure Patterns Predict Early- and Later-Onset Preeclampsia and Gestational Hypertension Among Ostensibly Low-to-Moderate Risk Groups,” can be located here at no cost.

The contents of this feature are not provided or reviewed by NPWH.