A low-dose aspirin (LDA) regimen initiated before conception may increase fecundability in some women with a recent early pregnancy loss, according to a new study in the Journal of Clinical Endocrinology & Metabolism.

In the multicenter, block-randomized, double-blind, placebo-controlled Effects of Aspirin in Gestation and Reproduction (EAGeR) trial, 1,228 women received either the intervention (81mg LDA plus 500mcg folic acid daily) or a placebo identical in appearance. The participants trying to conceive were 18–40 years of age with regular menstrual cycles, no known history of infertility, and confirmation of one or two prior pregnancy losses at <20 weeks during the preceding 12 months. The primary outcomes were time to pregnancy (TTP) and six-month cumulative incidence of pregnancy (hCG detected pregnancy or clinically confirmed pregnancy).

While women with a single documented pregnancy loss of <20 weeks’ gestation in the preceding 12 months saw a significant increase in fecundability and a shortened TTP, the higher rate of fecundability for women with a history of 1–2 pregnancy losses was not statistically significant. For women with a single pregnancy loss, the observed effect of LDA on TTP remained whether the pregnancy was hCG detected or clinically confirmed by early ultrasound. This could indicate that LDA influences ovulation, fertilization, and/or implantation. While the exact mechanism of action is unknown, it may be due to aspirin’s effect in increasing blood flow to the ovaries and endometrium.

Until additional research confirms these findings and explores any additional health risks or added benefits of preconception LDA treatment in women, recommending preconception LDA use is premature, the authors conclude.