Three-year-olds whose mothers had taken paracetamol on most days or every day during the second half of pregnancy were twice as likely to wheeze as children whose mothers had not taken the drug.

The authors of the study, published in the journal Thorax, 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 each year, they were asked about symptoms of wheezing and eczema in their children.

The research found that 1 per cent of women took paracetamol every day or most days between 20 and 32 weeks of pregnancy. These were twice as likely to give birth to children who wheezed at 3½ years old than those who had not taken the drug.

There was no evidence that less frequent use or heavy use of paracetamol before 20 weeks of pregnancy increase