Women who take an aspirin before sex may increase the likelihood of conceiving a baby boy, suggest researchers.
In a recent study, women with a history of miscarriages were more likely to give birth to a male child after taking aspirin around the time of conception compared with women given a placebo.
In fact, aspirin increased the likelihood of having a boy by nearly a third, reports the Journal of Clinical Investigation.
Previous research showed that recurrent miscarriage is linked to increased inflammation in the womb.
The theory is that the immune system sees the developing embryo as a foreign body, attacking it with inflammatory compounds and immune cells.
This inflammation may further reduce the likelihood of the woman having a boy because male foetuses are thought to be more vulnerable.
In Britain, there are slightly more female births than males.
External harmful factors, such as stress, pollution or smoking around conception have been associated with a reduction in the number of males, and suggest male embryos are more vulnerable for some reason.