The U.S. Preventive Services Task Force (USPSTF) reaffirmed its recommendations that pregnant women at a high risk of preeclampsia should take a daily aspirin regimen at the end of the first trimester.
In grade B recommendations, the USPSTF suggested a daily, low dose of aspirin (81 mg) for at-risk pregnant women to prevent preeclampsia after 12 weeks’ gestation, said task force members Karina Davidson, PhD, MASc, of Feinstein Institutes for Medical Research at Northwell Health, and co-authors.
Writing in JAMA, they explained that the USPSTF concluded with “moderate certainty” that there is “substantial net benefit” of a daily regimen of low-dose aspirin in high-risk pregnant women to reduce the risk of not only preeclampsia, but also preterm birth, small for gestational age or intrauterine growth restriction, and perinatal mortality.
These updated guidelines reaffirm the USPSTF’s 2014 recommendation on low-dose aspirin use for preeclampsia prevention, and add stronger evidence of the reduced risk of perinatal death. Both the American College of Obstetricians and Gynecologists and the Society of Maternal Fetal Medicine recommend low-dose aspirin for pregnant patients who are at risk.
“The findings from the updated evidence review and the accumulating evidence support the role of low-dose aspirin in the prevention of preeclampsia,” said Jimmy Espinoza, MD, MSc, of Baylor College of Medicine in Houston, writing in an accompanying editorial. There is insufficient evidence to recommend aspirin for patients with a history of stillbirth, or to prevent recurrent fetal growth restriction or spontaneous preterm birth in those who are not at risk of preeclampsia, he added.
“Accumulating evidence supports the notion that preeclampsia is associated with long-term health risks including increased risk for heart failure, coronary heart disease, stroke, diabetes, and death due to cardiovascular disease,” Espinoza wrote. It remains unclear whether preeclampsia during pregnancy predisposes patients to long-term cardiovascular disease, but future studies may help determine whether low-dose aspirin will affect whether high-risk patients develop long-term cardiovascular illness, he said.
Preeclampsia is one of the most serious health complications of pregnancy, and affects approximately 4% of pregnancies in the U.S., the task force stated. There are racial and ethnic disparities in prevalence and mortality related to preeclampsia, with Black patients facing a higher risk of developing the illness. Access to prenatal care and obstetric interventions could be responsible for racial disparities, the task force stated.
In an evidence report published with the recommendations, the USPSTF analyzed 23 randomized controlled trials of nearly 27,000 pregnant patients, all of whom were at a high risk of preeclampsia. A majority of patients in the review were white, and mean age was 20-34 years old. In the trials, participants received an aspirin dose of 50-150 mg or a placebo.
Pooling data from multiple studies, the task force found that high-risk pregnant women who took aspirin daily had around a 15% lower risk of developing preeclampsia (RR 0.85, 95% CI 0.75-0.95).
Low-dose aspirin also reduced the risk of preterm birth (RR 0.80, 95% CI 0.67-0.95), small-for-gestational age infants (RR 0.82, 95% CI 0.68-0.99), and perinatal mortality (RR 0.79, 95% CI 0.66-0.96).
There were no safety risks associated with taking a daily regimen of aspirin during pregnancy, including placental abruption or postpartum hemorrhage, the task force noted, adding that maternal complications, such as eclampsia and maternal death, rarely occurred in studies and could not be evaluated.
The task force noted that the studies varied in timing and dose of aspirin administration, and that the majority of available research evaluated the efficacy of either a 60 mg or 100 mg daily dose. However, the authors stated that low-dose aspirin is available in the U.S. as 81-mg tablets, which is a “reasonable dose for prophylaxis in pregnant persons at high risk for preeclampsia.”
Aspirin use was recommended for patients with one or more high risk factors for preeclampsia, including history of preeclampsia, multifetal gestation, chronic hypertension, pregestational diabetes, kidney disease, or an autoimmune condition, the task force said.
Pregnant women should also receive aspirin if they have two or more moderate risk factors, such as nulliparity, obesity, family history of preeclampsia, low income, maternal age over 35, or the use of in vitro fertilization to conceive, the task force said. As Black women experience preeclampsia at a disproportionately high rate, they are also considered at moderate risk.
The USPSTF stated that further research is needed to improve how clinicians identify pregnant women at risk of preeclampsia. The document emphasized that future trials should recruit patients at a disproportionately high risk, including Black women, to better estimate the efficacy of prophylaxis in populations with the greatest disease burden. In addition, the authors said, studies should investigate the optimal timing and dosage of aspirin.
The USPSTF is supported by the Agency for Healthcare Research and Quality.
Davidson and colleagues reported relevant financial relationships with the NIH, the National Institute on Aging, and the American Academy of Family Physicians.
One of the co-authors of the evidence report disclosed a financial relationship with Pfizer.
Espinoza did not report any potential conflicts of interest.