Women who take paracetamol frequently in late pregnancy are twice as likely to have a child who suffers persistent wheezing, researchers said yesterday.

A study of 9,000 pregnant mothers found that just 1% took paracetamol most days or daily.

But those who took it this often in late pregnancy were twice as likely to have children who suffered wheezing at the age of three and a half.

The authors of the study, published in the journal Thorax, said research on animals had suggested that very high levels of paracetamol could damage airway linings.

But whether this could occur in a baby's developing lung in the womb is unknown.

They state that if painkillers are required, expectant mothers should still take paracetamol rather than aspirin, but they should not use it every day.

The research was based on interviews with pregnant mothers who were taking part in the Avon longitudinal study of parents and children.

The study team led by Seif Shaheen of King's College in London, interviewed the women about their use of paracetamol and aspirin when they were 18-20 weeks' pregnant and again at 32 weeks.

Six months after giving birth and then every year, the mothers were asked about symptoms of wheezing and eczema in their children.

The research found that taking paracetamol every day or most days between 20 and 32 weeks of pregnancy was linked with a doubling in the risk of wheezing in the children when they were three and a half years old, compared with those whose mothers never took the drug during pregnancy.

The link was stronger still among children whose symptoms appeared before they were six months old.

There was no evidence that less frequent use or heavy use of paracetamol before 20 weeks of pregnancy increased the risk of wheezing for children. Nor was there anything to suggest that frequent use of paracetamol during pregnancy was linked to eczema in the children.

Press Association