Aspirin could help certain women get pregnant, study finds

Aspirin, an inexpensive and commonly available anti-inflammatory drug, could help some women who have had pregnancy losses in the past to sustain their pregnancy to a live birth, a new analysis suggests.

Researchers invited 1,228 healthy women (aged 18 to 40 years), who had experienced one or two previous pregnancy losses, to participate in a randomised trial from June 2007 to July 2011. The women, who were mostly white and educated, were given aspirin (81mg) or placebo during up to six menstrual cycles while trying to get pregnant and through 36 weeks of gestation if they conceived. All women were given 400μg folic acid. The researchers also classified the women into three groups depending on their serum levels of C-reactive protein (CRP), a biomarker for inflammation that aspirin is thought to act on.

Reporting their findings of their secondary analysis in the Journal of Clinical Endocrinology and Metabolism
^[1]
, the researchers found that women who benefited from the aspirin treatment had high levels of CRP.

They found no difference in birth rates between aspirin and placebo in both the low and mid-CRP groups (59% versus 54%; P=0.41 and 59% versus 59%; P=0.90, respectively).

However, in the high-CRP group, women taking placebo had the lowest rate of live birth at 44%, while those taking aspirin had a live-birth rate of 59% — a 35% rise (risk ratio [RR] 1.35, 95% confidence interval [CI] 1.08 to 1.67).

The researchers say the study highlights two concepts for the first time. “[First], systemic, chronic, low-grade inflammation may significantly harm women’s ability to become pregnant and the inflammation changes through pregnancy, and [second], this detriment may be restored to expected levels using preconception-initiated low-dose aspirin therapy.”

In terms of mode of action, they explain that cyclooxygenase (COX)-2 function, which is directly inhibited by aspirin, is interrelated with many inflammatory mediators involved in reproductive processes. As such, aspirin may inhibit the downstream effects of chronically upregulated inflammatory pathways.

The researchers conclude that more research is needed to confirm their data. “In addition to replicating the present findings, next steps should include further data collection to examine inflammation as related both to fertility and pregnancy outcomes. These collective findings should inform further discussion of any expanded use of aspirin in reproductive medicine, as well as the potential use of CRP as an informative screening test to guide its clinical application once appropriate clinical cut-points in this setting are also determined.”

Commenting on the study, Janine Elson, spokesperson for the Royal College of Obstetricians and Gynaecologists (RCOG), says: “This is an interesting study that suggests some women may benefit from taking aspirin once pregnant. Further research is needed to confirm these findings and women are advised only to take aspirin during pregnancy on the advice of their obstetrician or gynaecologist.”

• This story was updated on 21 March 2017 to clarify that the findings came from a secondary analysis.