The scientists insist their findings do not prove the drugs are directly responsible for causing cerebral palsy, but that they had simply found a link and more research is therefore needed.
Babies are more likely to suffer cerebral palsy if their mother took aspirin during pregnancy, a study suggests.
Newborns were almost two-and-a-half times more likely to have the incurable condition, which is caused by a brain injury and leads to life-long problems with speech and movement.
And those whose mothers took paracetamol while pregnant were up to 50 per cent more likely to have the condition, the study of more than 180,000 women found. But no link was discovered with ibuprofen.
Newborns were almost two-and-a-half times more likely to have the incurable condition, which is caused by a brain injury and leads to life-long problems with speech and movement, if their mothers took aspirin while pregnant, a UK study has found.
Currently, the painkillers are viewed as mostly safe for mothers-to-be, as long as they seek advice from their GP before taking them – but the team said this should now be reviewed.
Cerebral palsy, which affects nearly 2,000 babies a year in the UK, occurs if a baby’s brain does not develop normally while in the womb or is damaged during or soon after birth.
The damage can be caused by bleeding in the baby’s brain or by reduced blood and oxygen supply. Infection caught by the mother during pregnancy can also be a factor. But in many cases, the cause is not clear.
Symptoms such as muscle weakness, speech problems, blurred vision and learning disabilities may not show until the child is two or three.
There is no cure for the condition, which in some cases affects only one side of the body, but treatments such as physiotherapy and speech therapy can help sufferers live independent lives.
The scientists, from the University of Copenhagen, studied 185,617 mothers and their babies living in Denmark and Norway, quizzing mothers on their use of painkillers in pregnancy.
Around 5,000 of the women took aspirin and a similar number took ibuprofen. Nearly 90,000 – almost half – admitted taking paracetamol while expecting.
The team found 357 babies went on to develop brain-related problems – and those born to mothers who took aspirin were at the higher risk of developing cerebral palsy on both sides of the body.
Babies exposed to paracetamol were 30 per cent more likely to have overall cerebral palsy and 50 per cent more likely to have it on one side. Ibuprofen had little or no impact.
Those babies whose mothers took paracetamol while pregnant were up to 50 per cent more likely to have the condition, the study of more than 180,000 women found. But no link was discovered with ibuprofen
The researchers said the biggest danger seemed to be from taking the painkillers in the middle stage of a pregnancy, which is a crucial time for brain development.
They suggested drugs such as paracetamol and aspirin could trigger toxic conditions in the developing brain that lead to permanent damage, or could disrupt the normal level of a mother’s hormones needed to regulate brain development.
The researchers, who published their findings in the International Journal of Epidemiology, said: ‘It remains controversial whether prenatal exposure to paracetamol or aspirin affects neurodevelopment.
‘Use of paracetamol, aspirin and ibuprofen is generally perceived to be safe during pregnancy.
‘But there have been recent concerns about the effects on the developing brain.
‘The safety of these drugs now needs to be further evaluated and women should be further cautioned about their use in pregnancy.’
Dr Sunit Godambe, from the Royal College of Paediatrics and Child Health, said that although the study was large it did not prove a causal link between taking the drugs and cerebral palsy.
He added: ‘However, all medication in pregnancy should only be taken once a doctor has been consulted.’