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Low-dose aspirin may improve pregnancy chances for women with one or two prior miscarriages

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Catherine Morrow

New research suggests low-dose aspirin therapy before conception and during early pregnancy may increase pregnancy chances and live births among women who have experienced one or two prior miscarriages. The results of the study were recently published in Annals of Internal Medicine. 

Researchers from the National Institutes of Health and Emory University adjusted for differences in aspirin use between women who deviated from the daily regimen and those who adhered to it, rather than looking solely at the difference in pregnancy rates between women who were randomized to aspirin versus placebo.

Ashley Naimi, PhD, associate professor in epidemiology at Rollins School of Public Health, Emory University, lead the project with colleagues in the Epidemiology Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

“This work is the first to demonstrate that starting low-dose aspirin therapy while trying to become pregnant and taking it consistently four or five days a week until birth, may improve the reproductive outcomes of couples who have experienced one or two prior pregnancy losses,” says Naimi.

The Effects of Aspirin in Gestation and Reproduction (EAGeR) trial included more than 1,000 women between 18 and 40 years old with one or two previous miscarriages. The women received either daily low-dose aspirin (81 milligrams) or a placebo while trying to conceive. If they did conceive, they would continue to receive this regimen through the 36th week of pregnancy. Although the original study, published in 2014, found no overall difference in pregnancy loss rates between the two groups, there was a higher birthrate for the subgroup of women who had experienced only one previous miscarriage before the 20th week of pregnancy.

Unlike the original analysis, the current reanalysis considered whether a participant adhered to the treatment, skipped days or discontinued it entirely, possibly because of side effects such as bleeding, nausea or vomiting. The researchers found that, for every 100 women, adhering to the aspirin regimen for at least five days a week led to eight more positive pregnancy tests, six fewer pregnancy losses, and culminated in 15 more live births. Women who adhered to the therapy four days per week experienced similar results. The researchers concluded that taking low-dose aspirin at least four days per week could improve the odds for pregnancy and live birth in this group of women.

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