Allergic sensitisation in early childhood: patterns and related factors in a French birth cohort

Abstract

Introduction Allergic sensitisation is poorly documented in infants. This study aims to provide new insights into allergic sensitisation patterns and related factors in infancy. Methods This study concerns 1860 infants involved in a French population-based prospective birth cohort who had a standardised health examination when 18 month old. Sensitisation was assessed by measurements of specific IgE to 12 food and 4 inhalant allergens and defined by specific IgE ≥ 0.35 kUA/L. Information regarding lifestyle and environment were obtained from quarterly administered questionnaires. Results Prevalence of sensitisation to any allergen was 13.8%, with food allergen sensitisation superior to aeroallergen sensitisation: 12.3% versus 2.3%, respectively. Multi-sensitisation (≥ 2 allergens) concerned 6.2% of toddlers. Intrinsic factors such as male gender, family history of allergy, and high birth weight increased the risks of food allergen and multiple sensitisation whereas day-care attendance decreased these risks. Infants born by caesarean section were also more frequently multi-sensitised. Cat entering the baby’s room in early-life was strongly associated with aeroallergen sensitisation (ORa 3.21, 95% CI: 1.29–8.01). Introduction of meat in infant’s diet after 6 months was protective towards food allergen sensitisation (ORa 0.46, 95% CI: 0.24–0.91). Conclusions Our results suggest that intrinsic factors and indicators of exposure to infectious microorganisms such as caesarean section and day-care attendance are associated with sensitisation whatever the allergen’s origin. Conversely, early exposure to food allergens and aeroallergens could be specifically related to food sensitisation and to inhalant sensitisation, respectively. The apparent protective effect towards food allergen sensitisation of a delayed introduction of meat above the recommended age of 6 months questions the current guidelines about dietary diversification.