A small amount of daily aspirin can significantly reduce the risk of developing preeclampsia in pregnancy.
It is currently recommended for many pregnant women by two influential groups — the American College of Obstetricians and Gynecologists and the U.S. Preventive Services Task Force, an independent panel of experts commissioned by the federal government. Indeed, according to a comprehensive review of the scientific evidence by the USPSTF back in 2014, prenatal aspirin can cut the risk of preeclampsia by 24%. That guidance described the harms of taking low-dose aspirin in pregnancy as "no greater than small."
However, according to some OB-GYNs, the challenge is getting the word out to women who are at risk that the low-dose aspirin regimen is something that could benefit them. The cause of preeclampsia in a pregnant woman is still unknown, but the mechanism of danger is clear: Her blood vessels constrict, which means, among other things, blood can't flow easily to her kidneys or brain or uterus. Telltale signs include a terrible headache and swollen hands and feet.
"What aspirin does is relax blood vessels, [which] lowers the blood pressure, but also improves blood flow to the baby, to the kidneys, and to the brain, lowering the chance that the woman would have any complications to her pregnancy that would affect either her or her baby," says Dr. Jodi Abbott, an OB-GYN who specializes in treating high-risk pregnancies at Boston Medical Center and is also an associate professor at Boston University School of Medicine.
"It's been shown to be very safe," says Dr. Nyia Noel, who is Abbott's co-director of the Prenatal Aspirin Project, an initiative at BMC created to increase implementation of the task force's recommendations. "Things that people worry about — such as bleeding in pregnancy or something called placental abruption, which is early separation of the placenta — have not shown to be increased in women on low-dose aspirin."
Abbot says she doesn't see significant downsides to low-dose aspirin, she thinks it should just go to everybody who's pregnant. But not everyone is convinced — at least at this point — that every pregnant woman should take aspirin. Count Karina Davidson among them. She's the senior vice president for research at Northwell Health and a member of the U.S. Preventive Services Task Force panel that reviewed the evidence on this issue in 2014.
Still, that group's current recommendations stop short of advising prenatal aspirin for all.
"We have a very specific mandate, which is that we make recommendations based on evidence," Davidson says. "When we looked in 2014 we found little evidence that existed that in average-risk populations there was benefit." In other words, there needs to be a benefit to taking aspirin for women currently considered at low risk of developing preeclampsia — not just the absence of significant harm.