Researchers looked for evidence of interaction between paracetamol use during pregnancy or infancy and antioxidant genes in the mother or child. Variants in such genes may influence the toxicity of paracetamol.

Led by Professor Seif Shaheen, an expert of Respiratory Epidemiology at Barts and The London School of Medicine and Dentistry, the team examined data from the British Avon Longitudinal Study of Parents and Children (ALSPAC) which has followed 14,000 children since birth - beginning with their mothers' pregnancies and continuing into the children's 8th year.

Participating mothers reported on their use of paracetamol during pregnancy, as well as their child's exposure to the drug during infancy. Histories of wheezing and any asthma and allergy symptoms and diagnoses in the children were recorded, along with details of environmental exposures and family lifestyles. Between ages 7 and 8 the children had allergy skin and blood tests and lung function tests. Both mothers and children had genetic testing performed.

Shaheen and researchers found evidence suggesting that the risk of childhood asthma associated with prenatal paracetamol exposure depended on which variants of various antioxidant genes were present in the mother.

In contrast, interactions between infant paracetamol use and similar gene variants in the child were not seen. Shaheen added; "Our latest findings add further weight to the evidence implicating prenatal paracetamol exposure in the development of childhood asthma. However, ultimately a cause and effect relationship can only be confirmed through randomised clinical trials."; Source: Queen Mary, University of London