New study in JAMA Network Open shows current approaches to assessing preeclampsia risk are failing the majority of pregnant moms
By relying on maternal characteristics and broad demographics, guidelines identify 9 out of 10 pregnancies at increased risk, resulting in ineffective preventive care
Mirvie
South San Francisco, CA (July 17, 2025) - A new study sponsored by Mirvie, which is the first to evaluate U.S. Preventive Services Task Force (USPSTF) guidelines for preeclampsia risk and aspirin prescription in a single, nationally representative, prospective population, found while high-risk factors had sufficient value in estimating risk, there’s limited value for the moderate risk category - leading to nonspecific recommendations for aspirin use, a recognized prevention tool.
This cohort study of 5684 participants, culled from the multi-center Miracle of Life prospective study, found the guidelines identified nearly 89% of pregnancies at increased risk of preeclampsia. 70.3% were in the moderate risk category, defined by maternal characteristics and broad demographics including age, body mass index, and race, while 18.5% were in the high risk category, which includes patients with conditions like chronic hypertension or prior history of preeclampsia.
The study findings suggest that the murkiness of moderate risk factors may influence clinicians' decisions regarding daily aspirin recommendations. While 82% of women with a high risk factor were recommended daily aspirin, only 37% of those with one or more moderate risk factors were given this recommendation. USPSTF, American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) all endorse guidance to consider or recommend starting aspirin between 12 to 28 weeks’ gestation for pregnancies with moderate risk factors.
“Identifying 9 out of 10 women as at risk is not helping and overburdens care teams and pregnant patients, too,” said Dr. Thomas McElrath, vice president of clinical development at Mirvie and a practicing maternal-fetal medicine physician at Mass General Brigham, as well as lead author of the study. “Physicians may be reluctant to prescribe aspirin when the majority of their patients fall into the moderate risk category. This is compounded by less than 25% compliance with aspirin use by patients in the moderate risk category.”
Most pregnant women in the study (70.3%) fell into the moderate risk category using the USPSTF guidelines, but having one or more moderate risk factors and no high-risk factors were not predictive of preeclampsia risk. Among individuals with 2 or more moderate risk factors but without any high risk factor, nulliparity was associated with modestly increased risk of preeclampsia (RR, 1.48; 95% CI, 1.35-1.62; P < .001); there was little or no association with obesity (RR, 1.11; 95% CI, 1.01-1.22; P = .048), Black race (RR, 0.95; 95% CI, 0.80-1.14; P = .63), and advanced maternal age (RR, 0.79; 95% CI, 0.65-0.96; P = .02).
“Rates of preeclampsia in the US have doubled in the past 15 years and continue to rise with no end in sight,” said Kara Boeldt, a preeclampsia survivor and Founder and Executive Director of EndPreeclampsia.org. “The introduction of the USPSTF guidelines in 2021 didn’t do anything to reverse course on the rise of preeclampsia. This important and eye-opening study highlights that we need new approaches that can predict who’s truly at risk for preeclampsia, which can be so dangerous for moms and their babies. This is why I am incredibly encouraged and excited by the innovation being led by companies like Mirvie, which can finally offer some pregnant women and their care teams a clear, personalized prediction of their preeclampsia risk with a simple blood test during pregnancy."
“The findings of this important study confirm the need for clear, objective measures of preeclampsia risk prediction, to motivate preventive care,” said Maneesh Jain, CEO and co-founder of Mirvie. “With innovation like Encompass™, we can now deliver preventive care to the right patients at the right time and impact rates of preterm birth.”
About the Miracle of Life study
The Mirvie-sponsored Miracle of Life study examined nearly 11,000 pregnancies across the U.S., including 22,000 cell-free RNA transcripts per patient which resulted in 200 million data points overall, making it the largest study of molecular health in pregnancy of its kind. The landmark research study on pregnancy health, in collaboration with leading experts in obstetrics and maternal-fetal medicine, uncovers how RNA messages present in expectant mothers’ blood can predict life-threatening pregnancy complications. One area of study relates to cell-free RNA’s prediction of preeclampsia months in advance, a leading cause of pregnancy-related morbidity and mortality.
About Mirvie
Mirvie is bringing scientifically rigorous and data-driven approaches to solving some of the most pressing clinical problems in women’s health, beginning with pregnancy. Serious complications impact one in five pregnancies in the U.S., and Mirvie is committed to creating a world where every pregnancy is as safe and healthy as possible. Founded and led by a team of seasoned entrepreneurs and scientists, the company is based in South San Francisco, California and backed by top-tier investors including Blackrock, Decheng Capital, Foresite Capital, General Catalyst, GV, Khosla Ventures, and Mayfield. For more information, visit Mirvie.com.
Journal
JAMA Network Open
Method of Research
Observational study
Subject of Research
People
Article Title
Utility of the US Preventive Services Task Force for Preeclampsia Risk Assessment and Aspirin Prophylaxis
Article Publication Date
17-Jul-2025
Research Spotlight: evaluating the effectiveness of guidelines to predict the risk of preeclampsia
Mass General Brigham
Q: How would you summarize your study for a lay audience?
Dr. McElrath: Preeclampsia (PE) is a hypertensive disease that complicates 7-10% of pregnancies. While recent advances in understanding the underlying causes of PE have been made, predicting its occurrence has historically been difficult because it is a complex condition that likely results from a variety of causes and can present in different ways.
To address this challenge, the United States Preventive Services Task Force (USPSTF) reviewed a series of PE-associated studies to develop a set of risk factors to assist in characterizing patient risk of PE. However, since these risk factors were identified in individual and separate studies, they have not been evaluated as a whole to see how effective they are at stratifying risk within a single, diverse patient population.
We aimed to assess how well these guidelines help physicians identify patients at risk of PE and if those patients who were identified as being at-risk patients were directed to take aspirin as a preventative measure.
We found that using the USPSTF guidelines identified 89% of participants as being at either moderate or high risk for PE. With the vast majority of the population being labeled as “at risk,” it is unclear if the USPSTF guidelines are serving their intended use of helping clinicians identify patients at most need of additional care.
Furthermore, we found that only 37% of the participants who were identified as being at moderate risk were receiving the recommended prophylaxis of one low-dose aspirin per day, suggesting a gap still exists between risk identification and connection to preventative care.
Q: What question were you investigating?
How well do the risk assessment guidelines for preeclampsia that were developed by the USPTF work in identifying those at increased risk of preeclampsia?
Subsequently, how many of those individuals identified at increased risk are receiving a prescription of aspirin prophylaxis, as recommended by the American College of Obstetricians and Gynecologists and the Society of Maternal-Fetal Medicine?
Q: What methods or approach did you use?
We approached and enrolled 5,600+ individuals with singleton pregnancies who met the inclusion criteria for the study at 11 different centers in geographically diverse area of the United States.
For the purposes of the study, we defined individuals as being in the high-risk category if they had at least one high risk factor (as identified by the USPTF). Individuals were defined as being in the moderate risk category if they had at least one of the moderate risk factors, but no high-risk factors. Participants were defined as being in the low-risk category if they had no moderate or high-risk factors.
Q: What did you find?
Using the USPTF screening guidelines, we found that 18% of participants were in the high-risk category, 71% of participants were in the moderate risk category and 11% were in the low-risk category.
These categories were therefore labeling 89% of the population as at moderate or high risk for PE.
With the majority of the population being labeled as risk, it is unclear if the USPSTF guidelines are serving their intended use of assisting clinicians in stratifying preeclampsia risk.
The actual rates of PE for each of the three categories were as follows:
- 0% for those identified as low risk
- 5% for those at moderate risk
- 5% for those at high risk
While the majority of patients (82%) at high risk for PE received a recommendation for aspirin prophylaxis, patients at moderate risk for PE received recommendations at much lower rates.
Only about half of the patients with two or more moderate risk factors received recommendations for an aspirin prophylaxis while less than 25% of patients with one risk factor received a recommendation for aspirin.
Q: What are the implications?
If the intended utility of the guidelines is to facilitate the focus of clinical attention and limited clinical resources on those at greatest risk of preeclampsia, identifying the majority of the population as “at risk” does not meet this end.
Q: What are the next steps?
The risk factors for PE, and probably other conditions, should be simultaneously evaluated in a single population, not just compiled from the results of separate and individual studies, to ensure that they provide clinically actionable information that can assist with patient risk stratification and the alignment of clinical resources.
Journal
JAMA Network Open
Method of Research
Literature review
Subject of Research
People
Article Title
Research Spotlight: Evaluating the Effectiveness of Guidelines to Predict the Risk of Preeclampsia
Article Publication Date
17-Jul-2025
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