Maternal use of over-the-counter painkillers is about one and a half times more likely to increase the risk of delivering a baby with health issues, finds a study calling for reassessment of medical advice about the use of analgesics during pregnancy.

Researchers at the University of Aberdeen in the UK analysed data from more than 151,000 pregnancies over 30 years. The team looked at medical notes for non-prescribed maternal consumption of five common painkillers, paracetamol, aspirin and non-steroidal anti-inflammatory drugs (NSAIDs), diclofenac, naproxen, and ibuprofen, either as single compounds or in combinations

Among mothers who took painkillers such as paracetamol and ibuprofen during pregnancy, the risk of preterm delivery before 37 weeks was 50 per cent more likely, while the risk of stillbirth was 33 per cent.

Other risks of using painkillers include neural tube defects (64 per cent more likely); admission to a neonatal unit (57 per cent more likely); neonatal death (56 per cent more likely); and birthweight under 2.5 kg (28 per cent more likely), among others, revealed the study published in BMJ Open.

"It should be reinforced that paracetamol in combination with NSAIDs is associated with a higher risk and pregnant women should always consult their doctor or midwife before taking any over-the-counter drugs. We would encourage a strong reinforcement of the official advice for pregnant women," said Aikaterini Zafeiri from the University.

Between 30 per cent and 80 per cent of women globally use non-prescription painkillers in pregnancy to relieve pain for common pregnancy symptoms such as flu, fever, and inflammatory or rheumatological conditions.

However, current evidence regarding the safety of use during pregnancy varies widely, with some drugs considered safe and others not. Overall, nearly three in ten women have taken over-the-counter analgesics during pregnancy, a figure which more than doubled to 60 per cent during the last seven years of the 30-year study period. This suggests use is growing rapidly.

"In light of the study findings, the ease of access to non-prescription painkillers, in combination with the availability of misinformation as well as correct information through the internet, raises safety concerns. This is especially when misinformed or partially-informed self-medication decisions are taken during pregnancy without medical advice," Zafeiri said.