Taking aspirin, and certain other anti-platelet agents, may reduce the risk of pre-eclampsia in pregnant women during pregnancy and childbirth, according to a study published in The Lancet.

This conclusion is the result of a meta-analysis of women suffering from pre-eclampsia, which is a potentially fatal obstetric complication that can lead to sudden high blood pressure and irregular blood flow.

The Perinatal Antiplatelet Review of International Studies (PARIS) group looked at 63 clinical trials in 33 countries over 20 years, involving 32,217 women and their babies. Led by Lisa Askie of the National Health and Medical Research Council of Australia, the group noted that women who took aspirin in these trials typically took between 50mg to 150mg of the drug per day.

The researchers found the risks of developing preeclampsia dropped 10% among women taking aspirin or other antiplatelet medications and these women had a lower risk of delivering before 34 weeks and of having other pregnancy problems. Moreover, aspirin had no significant effect on the risk of death of the foetus or baby and it did not increase the risk of bleeding for either mothers or their infants, nor did it raise risks for underweight newborns.

Dr Askie's team said no particular group of women was more or less likely to benefit from aspirin and noted that “extensive subgroup and sensitivity analyses found no clear evidence that antiplatelet agents are more or less effective in preventing the development of pre-eclampsia for any particular group of women''.

However, in an accompanying editorial, James Roberts, the director of the Magee-Womens Research Institute at the University of Pittsburgh, said the results of this study were, “to a large extent, disappointing," as he had hoped it would shown a larger protective effect - especially in obese women who are at the greatest risk. "It's difficult to determine if it's more beneficial in any subset of women or at what dose," he added.

Still Dr Roberts said that in very high-risk women, the use of aspirin is justified adding that patients who are at the highest risk for pre-eclampsia are those who have high blood pressure and have also suffered the problem in previous pregnancies. This group "are almost certain to develop it," he said.

Women at risk because of high blood pressure, pre-pregnancy diabetes or pre-eclampsia in one previous pregnancy have about a 20% risk of developing pre-eclampsia, he noted, adding that “for these women, you would have to treat 50 with aspirin to prevent one case of preeclampsia”.