Pregnant women have been warned they have a potential risk of miscarriage if they take ibuprofen.
Researcher in Canada claim the pain killer increases the risk by 2.4 times if taken in the first 20 weeks of pregnancy.
The pain killer is one of a class of drugs known as non-steroidal anti-inflamatory drugs (NSAIDS) that also includes naproxen and diclofenac. Researchers looked at 4,705 cases of miscarriage and found that 352 (7.5 per cent) of the women who had suffered them had taken a non-aspirin NSAID.
The 15 to 45-year-old mums-to-be were then compared with 47,050 women of a similar age who had not lost their baby. The results found a total of 1,213 of them (2.6 per cent) had used an NSAID.
Dr Anick Berard, from the University of Montreal, said: 'The use of non-aspirin NSAIDs during early pregnancy is associated with statistically significant risk, a 2.4-fold increase, of having a spontaneous abortion.'
The report suggests that mums-to-be use paracetamol for pain relief instead.