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Preconception aspirin may be = placebo in preventing pregnancy loss (EAGeR)

Clinical Question:
Is preconception aspirin effective in preventing pregnancy loss?

Bottom Line:
This is not a definitive result, given the midcourse changes to the study design, but it appears that giving preconception aspirin to women who have experienced 1 or 2 pregnancy losses does not prevent subsequent pregnancy loss. (LOE = 2b)

Schisterman EF, Silver RM, Lesher LL, et al. Preconception low-dose aspirin and pregnancy outcomes: results from the EAGeR randomised trial. Lancet 2014;384(9937):29-36.  [PMID:24702835]

Study Design:
Randomized controlled trial (double-blinded)



Outpatient (any)

The Effects of Aspirin in Gestation and Reproduction (EAGeR) trial was a challenging study. It initially was designed to evaluate women between 18 years and 40 years of age who had one pregnancy loss at less than 20 weeks of gestation during the year before enrollment. However, because of slow enrollment, the researchers expanded the study to include women with 1 or 2 losses, regardless of gestation. These midcourse changes typically taint the final results and often bias the data in favor of interventions. The women received 81 mg aspirin plus 400 mcg folic acid (n = 615) or placebo plus folate (n = 613) every day. By the end of the study, 150 women had dropped out. The researchers ended a woman's participation when she had not conceived after 6 cycles or had 2 additional periconception losses. Overall, slightly more than 10% of the women in each treatment group experienced a subsequent pregnancy loss during follow up. The researchers designed the study to find a 10% absolute difference in pregnancy loss. The authors report that the rate of loss was lower in the subgroup of aspirin-treated women who had one pregnancy loss before 20 weeks’ gestation during the year before enrollment. Although this was their original cohort, they really can't claim this as a valid conclusion given the changes in the study. At best, it remains an inadequately tested hypothesis.


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