Women taking aspirin may be more likely to give birth to a boy

    8 July 2016

    Women who take aspirin before sex could increase the likelihood of conceiving a boy, a study has suggested.

    The report, which has been published in the Journal of Clinical Investigation, found that women with a history of miscarriages were a third more likely to give birth to a male child after taking aspirin at the time of conception, compared with women who were given a placebo.

    The researchers gave either aspirin or a placebo to 1,228 women who were trying to conceive. The women continued to take 81 milligrams a day – otherwise known as a ‘baby aspirin’ — until the 36th week of gestation.

    It was found that 31 per cent on aspirin had a boy, compared with 23 per cent of those on the placebo.

    Aspirin is an anti-inflammatory and it is thought that high levels of inflammation reduce the likelihood of a male embryo surviving. In support of this idea, women who have had one or two miscarriages are less likely to give birth to a boy than the general population.

    The theory is that the immune system may treat a developing embryo as a foreign body, and attack it with inflammatory compounds. A male embryo may be more vulnerable.

    Professor Simon Fishel, president of CARE Fertility clinics, told the Daily Mail: ‘It is a very interesting conclusion and more studies are needed to confirm if it is a potential solution to the apparent excess of female babies for women with evidence of inflammation.

    ‘Importantly, it relates only to women who have had miscarriages and evidence of inflammation. It does not have any bearing on sex ratios in normal conceptions where aspirin will not increase the chances of having a boy.’

    Instant analysis
    The study design was a randomised controlled trial looking at the effect of aspirin on the conception and birth rates of male foetuses.

    The rationale was that aspirin, being anti-inflammatory, would ameliorate the effect of inflammation in slightly reducing the proportion of boys being born. Evidence is available that higher levels of inflammation, whether due to a process within the body or from environmental exposure, reduces the incidence of a foetus being a male.

    The overall results suggest that aspirin use in women with higher levels of inflammation overall increases the incidence of male babies by 30 per cent. However, this includes both live births and babies that were miscarried; out of 127 pregnancy losses, only 84 underwent testing to determine the sex of the foetus, with a further 29 of these tests being indeterminate, a fact that could have falsely skewed the results.

    This is an interesting paper, but the findings require further study.

    Take-home message: there is no place for aspirin as part of sex selection; in terms of miscarriage in general, there is no place for aspirin except in women with specific inflammatory disorders.
    Research score: 2/5