Early life vitamin D levels and childhood respiratory morbidity and allergic sensitization

Background: Fetal and early-life exposure to vitamin D deficiency might affect the developing lung and influence the risk of respiratory diseases in later life. We examined the associations of 25-hydroxyvitamin D (25(OH)D) levels in mid-gestation and at birth with respiratory morbidity and allergic sensitization in childhood. Methods: In a prospective cohort study among 2,809 Dutch children, maternal blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25(OH)D levels (severely deficient 3-6 years) was obtained by annual questionnaires. At age 10 years, lung function was measured by spirometry, asthma by questionnaire, and inhalant allergen sensitization by skin prick tests. We examined associations using adjusted regression models. Results: Compared with optimal 25(OH)D levels at birth, severely deficient and deficient levels were associated with a higher risk of inhalant allergen sensitization (OR (95% CI): 1.47(1.00, 1.52); 1.54 (1.11, 2.13), respectively). Deficient 25(OH)D levels at birth were associated with a lower FEF75 (difference Z-score -0.11 (-0.23, 0.00)), compared to optimal levels. Only the latter association attenuated into non-significant after adjustment for 25(OH)D status in childhood. We observed no other associations of early life 25(OH)D levels with respiratory morbidity or allergic sensitization. Conclusion: Our results suggest that severely deficient and deficient 25(OH)D levels at birth are associated with a higher risk of inhalant allergen sensitization in childhood.