Women who receive aspirin or other antiplatelet drugs during pregnancy are at lower risk of pre-eclampsia, conclude authors of a study published early Online and in an upcoming edition of The Lancet. But an accompanying comment says that potential risks of aspirin use must be considered by individual mothers before embarking on treatment.
Pre-eclampsia is a multisystem disorder of pregnancy that is usually associated with high blood pressure and proteinuria (excess of serum proteins in the urine).
Dr Lisa Askie, University of Sydney, Australia, with funding from the Australian National Health and Medical Research Council, along with colleagues from Australia and the UK, formed the Perinatal Antiplatelet Review of International Studies (PARIS) collaborative group and did a meta-analysis (a study which combines the results of previous trials) on more than 32,000 women and their babies.
They found that the risks of developing pre-eclampsia, of delivering before 34 weeks and of having a pregnancy with a severe adverse outcome all fell by 10% in those women taking aspirin or other antiplatelet drugs.
Aspirin was found to have no significant effect on the risk of death of the fetus or baby, having a small for gestational age infant, or bleeding events for either the women or their babies. No particular subgroup of women was substantially more or less likely to benefit from aspirin than any other.
The cause of pre-eclampsia remains unclear, although it is known that complications in the maternal spiral arteries in early pregnancy can lead to irregular blood flow to the placenta, causing blood clots in and death to placental tissue. This can lead to activation of the platelets and clotting system and an imbalance between hormones which promote and slow blood flow. Antiplatelet agents such as aspirin are thought to prevent pre-eclampsia by redressing this balance.
The authors conclude: "Our data show that antiplatelet agents produce moderate but consistent reductions in pre-eclampsia and its consequences...This information should be discussed with women at risk of pre-eclampsia to help them make informed choices about their antenatal care."
In an accompanying comment, Professor James Roberts and Dr Janet Catov, Magee-Women's Research Institute and Departments of Obstetrics Gynecology and Reproductive Sciences and Epidemiology, University of Pittsburgh, Pennsylvania, USA, say:: "There are certain settings in which pre-eclampsia is almost a certainty, including women with pre-eclampsia in more than one pregnancy or women with chronic hypertension and pre-eclampsia in a previous pregnancy. In these settings, aspirin is justified.
"In the more usual setting of risk at about 20%, as in chronic hypertension, multiple gestations, pre-pregnancy diabetes or pre-eclampsia in one previous pregnancy, whether benefits outweigh theoretical long term risks is more difficult to judge."
They add: "Is treating 50 women to prevent one case of pre-eclampsia or one preterm birth worthwhile" Although from a public health perspective, such a number to treat might seem effective, the decision is one that is probably best made individually in consultation with an informed mother."