Pregnant women who suffer from stress are more likely to have a child with asthma, according to research from Children of the 90s study.
Researchers working with about 6,000 families in Bristol found anxious mums-to-be were 60% more likely to have a baby who would develop the illness. The findings show 16% of asthmatic children had mothers who reported high anxiety while pregnant.
Mothers-to-be who were less stressed had a lower incidence rate.
Professor John Henderson, from the Children of the 90s team, said: "Perhaps the natural response to stress which produces a variety of hormones in the body may have an influence on the developing infant and their developing immune system that manifests itself later on."
The Children of the 90s study - carried out by the University of Bristol - has been following 14,000 children.