Low-dose aspirin may increase the chances of pregnancy in certain women, according to a US study.
The study was a secondary analysis of the EAGeR (Effects of Aspirin in Gestation and Reproduction) project. Researchers from the National Institute of Child Health and Human Development in Maryland, USA, recruited 1128 women and randomly allocated them to receive either aspirin or a placebo tablet, with neither researchers nor participants knowing which they were taking.
Initial findings, reported in The Lancet in 2014, were that aspirin improved pregnancy and live birth rates only for women with a miscarriage within the last twelve months and not for all women. However, when researchers went on to analyse levels of inflammation using a blood marker called C-reactive protein (CRP), they found that pregnancy rates were lower when CRP was higher at baseline.
They found that in the group of women with higher CRP levels, taking aspirin increased pregnancy rates by 17 percent, from 57 to 67 percent. The researchers concluded that 'the anti-inflammatory effect of low-dose aspirin could be a mechanism by which it improves pregnancy rates in certain women'.
The study contributes to a debate about whether all women trying to conceive should take aspirin. Speaking at the American Society of Reproductive Medicine (ASRM) annual meeting where the research was presented, Professor Richard Paulson, who was not involved in the study, advocated daily low-dose aspirin for all women trying to conceive.
'Aspirin is the drug of the millennium,' he said, according to The Telegraph. 'There is no harm in women wanting to get pregnant taking aspirin. It increases blood flow to the pelvis, it increases endometrial thickness.' Professor Paulson, who is vice-president of the ASRM, added, according to the Huffington Post: 'This study adds to a body of literature about aspirin and pregnancy.'
Not all doctors agree with Professor Paulson's recommendation that all women trying to conceive should take aspirin, however. Dr Richard Kennedy of the International Federation of Fertility said there was insufficient evidence to change the current view. 'The evidence does not support its routine use in IVF,' he said.
Dr Adam Balen, chair of the British Fertility Society, also cautioned against extrapolating results from a conference presentation that is yet to undergo publication and peer-review, adding that 'there may be times when aspirin could be detrimental to fertility', according to The Pharmaceutical Journal.
Dr Nick Raine-Fenning, spokesperson for the Royal College of Obstetricians and Gynaecologists, highlighted some of aspirin's potential adverse effects. These include exacerbation of asthma , stomach ulcers, and its ability to cross the placenta into the baby's bloodstream. He did, however, welcome further research and said that 'this new study does show that targeted use may be worth considering in some women'.