New recommendations suggest that pregnant women at risk for preeclampsia should take a low-dose aspirin every day during their second and third trimester. The recommendations come from the U.S. Preventive Services Task Force and are based on findings suggesting that aspirin can lower the risk of preeclampsia, preterm birth, and low birth weight babies.  

Preeclampsia, which develops in about 4 percent of pregnancies, can be life threatening for both the woman and the fetus. Signs of preeclampsia include high blood pressure, protein in the urine, liver issues, and abnormal blood clotting. The condition causes blood vessels to constrict, which in turn causes high blood pressure and reduces blood flow to a woman’s organs. Women with preeclampsia are at immediate risk of a stroke and organ damage. As the name suggests, preeclampsia can lead to eclampsia, a rare and dangerous condition in which pregnant women have seizures.

Once a women is found to have preeclampsia, the only way to protect her health is to deliver the baby regardless of how far along she is in her pregnancy, which is why the most common outcome for preeclampsia is preterm births and low birth weight babies. Preeclampsia also constricts blood flow to the uterus, which can cause the fetus to grow more slowly than expected, limit the amount of amniotic fluid, or cause the placenta to separate from the uterine wall before delivery (a life-threatening condition for both mother and fetus called placental abruption).

Even after delivery, women who have had preeclampsia have an increased lifetime risk of cardiovascular issues, including high blood pressure and stroke—in fact, a study released in February found that women who’ve had it have twice the risk of stroke and four times the risk of high blood pressure later in life.

The good news is that research now confirms that a simple aspirin regimen may be able to prevent the condition from developing. A systematic review of research published in the Annals of Internal Medicine found that the low-dose aspirin regimen (81 milligrams per day after the first trimester) reduced the incidence of preeclampsia by 24 percent. Ira M. Bernstein, chair of the department of obstetrics and gynecology at the University of Vermont, put it this way when he spoke to the New York Times: “For every four women who would have gotten pre-eclampsia, one case is prevented. The ability to prevent a quarter of disease is substantial.” The review also found that the aspirin regimen reduced incidences of premature birth by 14 percent and slow fetal growth by 20 percent.

The aspirin regimen was found to be safe; it did not increase the risk of bleeding after delivery, placental abruption, or bleeding inside the newborn’s cranial cavity.

Based on the review, the task force recommends the regimen for anyone at high risk of preeclampsia, which includes women who have already had a pregnancy in which they developed the condition, especially if they delivered preterm; women who are carrying multiple fetuses; and women who already had diabetes or high blood pressure when they got pregnant. It noted that women with other factors considered to be a moderate risk for preeclampsia—including women who are obese, have a family history of preeclampsia, are over 35, or are African American—may want to consider the aspirin regimen and discuss it with their obstetricians.