title: Cord blood 25(OH)D levels and the subsequent risk of lower respiratory tract infections in early childhood: the Ulm birth cohort.
abstract: Lower respiratory tract infections (LRTIs) are a major cause of hospitalization in infants. Research suggests that immunomodulatory properties of vitamin D may influence LRTI risk. This study's objective was to examine whether 25-hydroxyvitamin D [25(OH)D] concentrations in cord blood influenced susceptibility to LRTI in the first year of life. Data was analyzed from a prospective birth cohort of 777 mother-infant pairs based in Ulm, Germany. Relative risks (RRs) of LRTI in relation to 25(OH)D cord blood levels were estimated by log-binomial regression after adjustment for potential confounders. To account for seasonal variation in both vitamin D levels and infections, we examined the association in different seasons. Analyses were conducted using clinical predefined cutpoints, quartiles, and season-standardized 25(OH)D quartiles. We observed a statistically significant association between 25(OH)D status in cord blood and risk of LRTI across the year using clinical cutpoints. The adjusted RR of LRTI for individuals with vitamin D deficiency (<25 nmol/L) in comparison to the referent category (>50 nmol/L) was 1.32 [95 % confidence interval (CI) 1.00, 1.73]. The association differed by maternal allergy status; children born to mothers without allergy demonstrated a RR of 1.45 (95 % CI 1.03, 2.03). The effect was largely driven by a strong association between 25(OH)D and LRTI in infants born in fall with a RR of 3.07 (95 % CI 1.37, 6.87). Our findings suggest that vitamin D deficiency at birth is associated with increased risk of LRTI particularly in infants born to mothers without allergy. The association seems strongest in infants born in fall.
authors.affiliation: Center for Chronic Immunodeficiency (CCI), Molecular Epidemiology, University Medical Center Freiburg, Engesser Strasse 4, 79108, Freiburg, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Łuczyńska
authors.forename: Chad
authors.initials: C
authors.lastname: Logan
authors.forename: Alexandra
authors.initials: A
authors.lastname: Nieters
authors.forename: Magdeldin
authors.initials: M
authors.lastname: Elgizouli
authors.forename: Ben
authors.initials: B
authors.lastname: Schöttker
authors.forename: Hermann
authors.initials: H
authors.lastname: Brenner
authors.forename: Dietrich
authors.initials: D
authors.lastname: Rothenbacher
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D005312:Fetal Blood; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D016015:Logistic Models; D008297:Male; D009035:Mothers; D011159:Population Surveillance; D015995:Prevalence; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000097:blood / Q000453:epidemiology*; D012307:Risk Factors; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood; D014815:Vitamins / Q000097:blood* / Q000378:metabolism
chemical_list: D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D