Predictors of atopic disease: cord blood IgE and month of birth.

The cumulated incidence of atopic disease before 7 years of age was highly influenced by the cord blood IgE concentration and moderately influenced by the month of birth: obvious atopic disease was more than twice as common in children with high cord blood IgE and born in May than in children with a similar IgE and born in November (P less than 0.05). There was no similarly increased risk for atopic disease among those born in May with low cord blood IgE. Environmental factors thus seem important merely for a high risk population. The findings lend support to family planning when there is especially high genetic risk for atopic disease.