NSAIDs (non steroidal anti inflammatory drugs) taken during pregnancy can increase the risk of miscarriage by up to seven times.

The risk was discovered by Danish researchers who studied more than 4000 women who had miscarried and compared them with nearly 30,000 women who had live births.

They found the risk of miscarriage to be related to hospital prescription for an NSAID, and was greatest within a week of receiving the prescription 6.99 times greater. This suggests that there is a group of vulnerable women for whom NSAID use translates quickly into miscarriage.

In a separate analysis using the same data, the team evaluated pregnancy outcomes for 1462 women who purchased NSAIDs anywhere from 30 days before conception until birth. The outcomes of these births were compared with those of more than 17,000 pregnant women who were not prescribed any drugs during pregnancy. Analysis showed that NSAID use did not significantly increase the risk of abnormalities, low birth weight or premature birth.

The association between NSAIDs and miscarriage is new. However, given the size of the study, the Royal College of Obstetricians and Gynaecologists suggests that pregnant women avoid drugs such as aspirin, particularly since alternatives like paracetamol are effective (BMJ, 2001; 322: 266-70).

Another new study advises doctors to assess their patients' risk of heart disease before doling out aspirin. This warning comes after a meta analysis of four randomised trials of aspirin often used as primary prevention of coronary heart disease in those thought to be at increased risk found that indiscriminate prescriptions for aspirin may cause more complications than they prevent. For instance, while aspirin can cut the risk of a first heart attack by one third, it can increase bleeding complications by almost 70 per cent (Heart, 2001; 85: 265-71).