Guidance on taking painkillers during pregnancy should be reassessed following a study that found a link to newborn health problems, experts have said.

Researchers at the University of Aberdeen found pregnant women who use over the counter analgesics are around one and half times more likely to have a baby with health issues.

The risk of preterm delivery, stillbirth or neonatal death, physical defects and other problems are all higher compared with the offspring of mothers who did not take pain killers such as paracetamol and ibuprofen whilst pregnant.

The study, one of the largest of its kind, was published in BMJ Open.

Between 30% and 80% of women globally use over the counter painkillers to relieve symptoms of flu, fever, and inflammatory or rheumatological conditions which can be common in pregnancy. However, current evidence regarding the safety of using these medicines during pregnancy varies widely, with no consensus on which painkillers should or should not be used.

The researchers determined maternal consumption of five common pain killers over a 30 year period between 1985 and 2015. Using data from more than 151,000 pregnancies recorded with the Aberdeen Maternity and Neonatal Databank, they examined the medical notes of the pregnant women for evidence of pain killer use, specifically paracetamol, aspirin, and non-steroidal anti-inflammatory drugs (NSAIDs), diclofenac, naproxen and ibuprofen. They also looked at any combined use of these five medicines during pregnancy.

Where mothers were exposed to at least one of the five painkillers, neural tube defects were 64% more likely, admission to a neonatal unit was 57% more likely, neonatal death was 56% more likely, and premature delivery before 37 weeks was 50% more likely.

In addition, the researchers found that painkiller use had more than doubled among pregnant women in the last seven years of the study, with a record 60% of pregnant women taking over the counter analgesics in this period.

First author of the paper, Aikaterini Zafeiri of the University of Aberdeen, said: ‘In light of the study findings, the ease of access to non-prescription painkillers, in combination with 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.’

She added: ‘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.’

This comes after two UK randomised controlled trials in May found home blood pressure monitoring in higher risk pregnancy does not improve hypertension detection or control compared with usual care.