Maternal and neonatal 25-hydroxyvitamin D concentrations and school-age lung function, asthma and allergy. The Generation R Study.

Background: Vitamin D deficiency in early life might affect the developing lung and immune system, and subsequently influence the risk of asthma and allergy in later life.

Objective: We examined the associations of 25-hydroxyvitamin D concentrations in mid-gestation and at birth with lung function, asthma, inhalant allergic sensitization and inhalant allergy at school-age.

Methods: This study among 4951 children and their mothers was embedded in a population-based prospective cohort in Rotterdam, the Netherlands. Maternal venous blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D concentrations. At age 10 years, lung function was measured by spirometry, current asthma and physician-diagnosed inhalant allergy by questionnaire, and inhalant allergic sensitization by skin prick tests. We used multivariable regression models to examine associations.

Results: Higher 25-hydroxyvitamin D concentrations in mid-gestation were associated with a higher forced vital capacity (FVC), but a lower forced expiratory volume in 1 second/FVC (FEV /FVC) and a lower forced expiratory flow after exhaling 75% of FVC (FEF ) (Z-score differences [95% CI] 0.02 [0.00, 0.03], -0.02 [-0.03, -0.01] and -0.01 [-0.03, -0.00], respectively, per 10 nmol/L 25-hydroxyvitamin D), but not with asthma. Furthermore, higher 25-hydroxyvitamin D concentrations in mid-gestation were associated with an increased risk of inhalant allergy (Odds Ratio [95% CI] 1.07 [1.02, 1.12]), but not with inhalant allergic sensitization. After additional adjustment for child's 25-hydroxyvitamin D concentrations at the age of 6 years, only the associations of 25-hydroxyvitamin D concentrations in mid-gestation with FEV /FVC and FEF remained. We did not find consistent associations of 25-hydroxyvitamin D concentrations at birth with respiratory or allergy outcomes.

Conclusion And Clinical Relevance: Our results suggest that maternal 25-hydroxyvitamin D concentrations in mid-gestation may influence lung development. The clinical implications of the observed associations remain unclear.