Neonatal risk factors of atopic dermatitis in Denmark - Results from a nationwide register-based study

Background: Atopic dermatitis (AD) is a chronic inflammatory skin condition with a multifactorial etiopathogenesis. Studies have suggested that several perinatal factors may influence the risk of AD in early childhood. We investigated possible neonatal risk factors such as jaundice, blue light phototherapy, birthweight, gestational age at birth, and season of birth on the risk of developing AD in the first 5 years of life. Materials & Methods: Data were collected through Danish nationwide administrative registers. All newborn children between 1997 and 2007 (n = 673,614) were included in the cohort. Incidence rate ratios (IRRs) were estimated with 95% confidence intervals (95% CIs) by multivariate Poisson regression analyses. Results: We identified a total of 85,743 children with AD in the first 5 years of life. The risk of AD was slightly increased in children with neonatal jaundice (IRR 1.13 [95% CI 1.06-1.21]). Preterm birth was inversely associated with the risk of AD (IRR 0.74, [95% CI 0.68-0.81]) as well as low birthweight (IRR 0.68, [95% CI 0.61-0.75]). Children born in fall and winter seasons had an increased risk of AD compared to spring and summer. No association between neonatal blue light therapy and the risk of AD was found. Conclusions: Low birthweight and preterm birth were inversely associated with AD, while neonatal jaundice and cold seasons of birth were associated with an increased risk of AD.