By Andrew M. Seaman
NEW YORK (Reuters Health) - Pregnant women at a high risk for the potentially fatal complication preeclampsia should take low-dose aspirin after their first trimester, according to a government-backed panel.
The draft recommendation from the U.S. Preventive Services Task Force (USPSTF) is based on a review of the evidence that found low-dose aspirin reduced the likelihood of developing the condition and its complications.
"Low-dose aspirin - in looking at benefit - reduced the risk of preeclampsia by 24 percent," Jillian Henderson, the review's lead author, told Reuters Health.
The therapy also reduces the risks of having to deliver the baby early and of the baby growing too slowly in the womb, she said.
Henderson is a researcher at the Kaiser Permanente Center for Health Research Northwest in Portland, Oregon. She is not a member of the USPSTF.
Preeclampsia is a condition that occurs in 2 to 8 percent of pregnancies. It's defined by the onset of high blood pressure and high urine protein levels during pregnancy, according to the USPSTF.
The condition is one of the leading causes of maternal death worldwide. It's also responsible for 15 percent of preterm births in the U.S.
For the new review, the researchers searched several databases for past studies that examined the risks and benefits of low-dose aspirin in the prevention of preeclampsia.
"We found 23 studies that were considered good enough to include in the summary of this evidence," Henderson said.
They found that taking a low-dose aspirin reduced the risk of preeclampsia by 24 percent. It also reduced the risk of preterm birth by 14 percent and the risk that the baby would grow too slowly in the womb by 20 percent.
About 4 percent of U.S. deliveries in 2010 were affected by preeclampsia, the authors note in their report, published in the Annals of Internal Medicine.
It's hard to know what a 24 percent reduction would mean to that number, because the reduction would be in high-risk women and we don't know how many of them there are, Henderson said.
But even in an ideal world it's likely that at least 3 percent of pregnancies would still be affected by the condition.
"Because the outcomes are so serious, we care about a small reduction," Henderson said.
The researchers were not able to identify any harms associated with taking low-dose aspirin.
While there is no way to predict which women will go on to develop preeclampsia, the USPSTF refined the recommendation for women based on high and moderate risk factors.
Women with one high risk factor should take a low-dose (81 milligram) aspirin every day after 12 weeks of pregnancy, the panel advises. The same goes for women who have multiple moderate risk factors.
High risk factors include prior preeclampsia, having twins or multiple babies, high blood pressure, diabetes and having kidney or autoimmune diseases. Moderate risk factors include first time pregnancy, obesity, being older than 35 years and being African American or of low socioeconomic status.
"This certainly expands the therapy to a lot more women and will certainly expand our offering to more women," Dr. Loralei Thornburg said.
Thornburg was not involved in making the new recommendation. She is a high-risk pregnancy expert at the University of Rochester Medical Center in New York.
She said the American College of Obstetricians and Gynecologists currently recommends low-dose aspirin therapy, but only for women who have a history of preeclampsia.
Henderson cautioned that women shouldn't start taking low-dose aspirin without talking to their doctors first.
"It shouldn't be something done with a broad brush that people are considering for themselves," she said.
The new USPSTF recommendations are available for public comment until May 5 here: http://bit.ly/ZKptK6.
SOURCE: http://bit.ly/1qgpm91 Annals of Internal Medicine, online April 7, 2014.
(This story has been refiled to revise paragraph 12 to clarify the relative risk reduction among high-risk women, and inserts paragraph 13.)