Low-dose aspirin improves chances of pregnancy after miscarriage

Women with previous pregnancy losses who adhered to a low-dose aspirin regimen while trying to conceive had better outcomes than women who received placebo, results from a per protocol analysis of a randomized trial showed.

“Pregnancy loss is one of the most common adverse pregnancy outcomes, and existing treatments tend to have a heavy patient burden,” Ashley I. Naimi, PhD, an associate professor in the department of epidemiology at Emory University in Atlanta, told Healio Primary Care.

Previously, data from the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial showed that preconception-initiated low-dose aspirin (LDA) was associated with a 10% increase in live births compared with placebo among women with one or two previous miscarriages, but researchers found no significant impact of LDA on pregnancy loss. However, the findings were “subject to complications,” including nonadherence to treatment, Naimi and colleagues wrote in Annals of Internal Medicine.

“The implications of previous research on whether aspirin could prevent pregnancy loss were unclear,” Naimi said. “We sought to address this lack of clarity and explored whether taking aspirin every day for at least 4 days per week could lead to an improvement in pregnancy outcomes.”

Naimi and colleagues retrospectively reviewed data from the EAGeR trial. Conducted from 2007 to 2011, EAGeR randomly assigned 1,227 women aged 18 to 40 years with one or two prior pregnancy losses in a 1:1 ratio to take 81 mg of aspirin or placebo daily throughout six menstrual cycles. Women who conceived were also instructed to take their assigned regimen until the 36th week of pregnancy. The researchers, unlike EAGeR analysis predecessors, also considered whether a woman adhered to the treatment, skipped it or stopped taking it altogether for adverse events such as bleeding, nausea or vomiting.

Naimi and colleagues reported that relative to placebo, LDA adherence for 5 of 7 days weekly led to eight more positive pregnancy tests (95% CI, 4.64-10.96 pregnancies), 15 more live births (95% CI, 7.65-21.15 births), and six fewer pregnancy losses (95% CI, –12.00 to –0.2 losses) for every 100 women in the trial. The observed effects of LDA were achieved in a minimum of 4 days of weekly therapy and were reduced when LDA was initiated after conception.

“Adherence is key” to replicating the results in the real-world clinical setting, according to Naimi; however, ways to improve adherence rates remain elusive.

“Research on improving adherence — for example, through alternative routes of LDA delivery — or provider and patient education on the need to maximize adherence may help increase the potentially beneficial effects of LDA on pregnancy outcomes,” Naimi said.