Based on its review of the available evidence, the task force recommended low-dose aspirin (81 mg/day) as preventive medication after 12 weeks of gestation in patients who are at high risk for preeclampsia. This is a “B” recommendation, and it applies to pregnant patients who are at high risk for preeclampsia and who have no prior adverse effects with or contraindications to low-dose aspirin.
“The good news is that daily aspirin use can help prevent preeclampsia in high-risk pregnant people and protect their health and the health of their baby,” said Aaron Caughey, M.D., M.P.P., M.P.H., Ph.D., a member of the task force, in a news release. “Before taking aspirin, pregnant patients should talk to their clinician to determine their risk and discuss if taking aspirin is right for them.”
The CDC estimates that preeclampsia occurs in about 4% of all pregnancies in the United States. Although the cause is unclear, it is an inflammatory syndrome that affect multiple organ systems and often is progressive. Several factors can increase a woman’s risk of preeclampsia, including (but not limited to) chronic high blood pressure, chronic kidney disease, type 1 or type 2 diabetes, autoimmune disease and obesity. Non-Hispanic Black individuals, as well as those who have a personal or family history of preeclampsia, are giving birth for the first time, are pregnant with multiple babies or used in vitro fertilization to become pregnant, and those age 35 and older also are at increased risk.
The current draft recommendation is consistent with the task force’s previous recommendation statement on the topic, which was published in 2014. In that recommendation, the USPSTF recommended low-dose aspirin as a preventive medication after 12 weeks of gestation in patients at high risk for preeclampsia. The AAFP supported the 2014 recommendation.
To update the existing recommendation, the USPSTF commissioned a systematic review to evaluate the effectiveness of low-dose aspirin use to prevent preeclampsia in pregnant patients at increased risk, and to decrease adverse maternal and perinatal health outcomes. The review also assessed the maternal and fetal harms of using low-dose aspirin use during pregnancy. The evidence review included a search of new studies published between January 2013 and July 2019, and also considered studies that were included in the previous review. Overall, 23 studies met the researchers’ inclusion criteria, including evidence from four new trials.
The task force found that daily use of low-dose aspirin in patients at increased risk for preeclampsia, usually starting in the second or third trimester and continuing until delivery or near term, resulted in reductions in risks for perinatal mortality, preterm birth and small for gestational age/intrauterine growth restriction. There also was a statistically significant reduction in the risk of preeclampsia. Maternal complications were rare and, as such, could not be evaluated.
Results from studies conducted in both average- and increased-risk populations did not demonstrate any clear evidence of harms associated with daily aspirin use. Bleeding-related harms were uncommon, and pooled results were not statistically significant for risk of fetal intracranial bleeding, placental abruption or postpartum hemorrhage.
“Even if aspirin has only modest effectiveness for improving pregnancy outcomes, their importance suggests that the intervention could have important implications for population health and well-being across the lifespan,” the researchers wrote.
In the evidence review, the researchers noted that most participants in the included trials were white. While two trials included substantial numbers of Black and Hispanic participants, none of the studies enrolled significant numbers of other minority racial or ethnic groups. Given recent evidence that indicates that Black women are at increased risk of preeclampsia, along with research showing disparities in maternal health and birth outcomes among Black women in the United States, the research team stated that more studies are needed to address this evidence gap.
“It is essential that the health community focus on why the disparities exist and what changes can be made to improve health outcomes for Black people and their babies,” said task force member Michael Silverstein, M.D., M.P.H. “The task force is committed to addressing this disparity and is calling for more research on how best to prevent preeclampsia in Black people who are pregnant.”
In addition, the investigators called for more research on ways to improve recognition of pregnant patients who are at increased risk for preeclampsia, along with comparative effectiveness trials to determine the specific aspirin protocol likely to provide the greatest benefit.
The AAFP will review the USPSTF's draft recommendation statement and supporting evidence and will provide comments to the task force.