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• Posted May 6, 2024

New Test Might Alert Pregnant Women to Preeclampsia Danger

A potentially dangerous spike in blood pressure known as preeclampsia can occur in 1 in every 25 pregnancies, but an accurate test to spot those women at highest risk has remained elusive.

Now, Canadian researchers at Université Laval in Québec City say they've developed an algorithm that seems to do just that. 

In their study of more than 7,000 pregnant women, the test outperformed standard measures to pinpoint high-risk pregnancies.  

That could be a great tool for doctors, who can advise such women to take daily low-dose aspirin to lower their odds for preeclampsia.

"Using this new screening model, treatment decisions were based on each individual's personal risk,"said study senior author Dr. Emmanuel Bujold, professor of obstetrics and gynecology at the university. 

"With their personal risk calculated, it's much easier for a woman to make the right decision," he explained. "For example, if she chooses to take daily low-dose aspirin, she is much more likely to follow through because it's based on personalized screening test."

The findings were published May 6 in the journal Hypertension.

Preeclampsia is defined as a dangerous rise in blood pressure during pregnancy -- anything over 140/90 mm Hg. Unchecked preclampsia is one of the leading causes of maternal death worldwide.

For the mother, preeclampsia can cause headaches, vision changes and swelling of the hands, feet, face or eyes. It can also show up as a decline in fetal wellbeing, the American Heart Association (AHA) said in a news release.

"Preeclampsia is one of the most severe illnesses of pregnancy and may lead to preterm birth and/or maternal death,"Bujold said in the news release. 

While preeclampsia can begin to develop in the first trimester, it often doesn't appear until week 20 or beyond. 

Right now, guidelines based on certain risk factors -- prior history of preeclampsia, chronic high blood pressure, Type 2 diabetes, chronic kidney disease or lupus -- are signs used by doctors to suggest that a woman may need to take daily aspirin to lessen the risk.

Aspirin is also recommended for women with two "moderate" risk factors for preeclampsia. Among those risk factors are Black race; having a mom or sister who's also had preeclampsia during a pregnancy; obesity; pregnancy by in vitro fertilization (IVF); or being pregnant for the first time (preeclampsia is more common in first pregnancies).

"Following those guidelines, almost all Black women should take aspirin during pregnancy, as should about one-third of all women of other races and ethnicities,"Bujold explained. 

But what if there was an even more accurate way of spotting women at risk?

To find out, Bujold's group turned to a model developed by the Fetal Medicine Foundation. It employs a combination of maternal history, ultrasound and blood biomarker tests to screen women for preeclampsia risk.

The study group included more than 7,000 pregnant Canadian women averaging 29 years of age, all observed during first-time pregnancies.  

The Quebec City team found that the Foundation's algorithm, used between weeks 11 and 13 of pregnancy, was about 63% accurate in predicting preterm preeclampsia (occurring before 37 weeks of gestation).

It was even better at spotting early preeclampsia (occurring before 34 weeks of pregnancy), with a 77.3% accuracy rate, the researchers said.

Compare that to accuracy of the American College of Obstetricians and Gynecologists' (ACOG) risk factor-based guidelines. That prediction model had a 61.5% accuracy rate for predicting preterm preeclampsia, and a 59.1% accuracy for predicting early preeclampsia, Bujold's team noted.

As well, ACOG's model had a false-positive rate of 34.3% -- meaning that a third of women who'd been told they were at high risk for preeclampsia were actually not.  

"This would be more than twice the false-positive rate of the Fetal Medicine Foundation's screening model," the AHA noted in the news release.

A more precise means of predicting preeclampsia would more reliably get daily low-dose aspirin to the women who need it . The AHA said the aspirin regimen can lower the odds for preeclampsia by up to 53%.

One expert who didn't take part in the study said the new algorithm might prove extremely valuable.

"Since the risks for preeclampsia may be largely influenced by health before pregnancy, the ability of a screening model to be applied in early pregnancy is very helpful and can initiate conversations between the clinician and patient about strategies to optimize heart health,"said Dr. Sadiya Khan. She is chair of the writing group for the AHA's latest scientific statement on Optimizing Prepregnancy Cardiovascular Health to Improve Outcomes in Pregnant and Postpartum Individuals and Offspring.

There are some hurdles to overcome before the Foundation's test could become mainstream, however.

"Challenges remain with implementation of models such as this one that integrate biomarkers that are not routinely assessed and may not be widely available, especially among people in vulnerable populations who are most likely to have the highest risk for preterm preeclampsia," Khan said in the AHA news release.

More information

Find out more about preeclampsia at the March of Dimes.

SOURCE: American Heart Association, news release, May 6, 2024