Children's Oral Habits and Risk for Allergy and Asthma

Does elevated exposure to environmental microorganisms in childhood result in lower risk for atopy later in life? To address this question, researchers assessed whether thumb-sucking or nail-biting habits in children were associated with reduced rates of atopic sensitization, asthma, or hay fever in a prospective birth-cohort study of New Zealand residents. Thumb-sucking and nail-biting were assessed via parental questionnaire at ages 5, 7, 9, and 11 years. Skin-prick testing for selected antigens was conducted in most participants at ages 13 and 32 years, at which time asthma and hay fever were self-reported.

Among 1013 participants, having one or both habits (prevalence, 31%) was associated with reduced risk for atopic sensitization at age…