A study of 24,690 children suggests that exposure to antibiotics in the womb is associated with an increased risk of asthma in children. Approximately one third of the children?s mothers were prescribed 1 or more courses of antibiotics during pregnancy. Use of more than 2 courses of antibiotics by the mothers was linked to an adjusted hazard ratio for asthma in their children of 1.68, for hay fever of 1.56, and for eczema of 1.17. These associations were dose-related, the researchers reported in the American Journal of Respiratory and Critical Care Medicine. In addition, infections in the mother (eg, those in the gastrointestinal and respiratory tracts) were also linked to a slightly increased risk of allergic disease.