Vitamin D Levels in Premature Children Admitted to the Hospital with Viral Respiratory Infection.

Children born preterm are at risk of hospital admission for respiratory infection in the first years of life. Vitamin D deficiency has been associated with increased risk of developing lower respiratory tract infection (LRTI). We assessed vitamin D levels in children born preterm admitted to the hospital ward or pediatric intensive care unit (PICU) with viral LRTI. A prospective observational cohort study was conducted over 3 years that enrolled 87 children <3 years of age, born <37 weeks of gestation. Children were enrolled in the ward and PICU if they had a diagnosis of LRTI with confirmed viral testing. Children seen in the outpatient clinic for well-child care were enrolled as study controls. Vitamin D and cathelicidin levels were measured and associations between vitamin D, cathelicidin, and admission sites were tested. Vitamin D levels were lower in children admitted to the PICU when compared to controls (28 ng/mL versus 36 ng/mL; < 0.03) but were not different between children admitted to the ward or PICU. Overall, vitamin D levels were lower in children born late preterm (≥34 weeks, LPT) when compared to those born early preterm (<34 weeks, EPT), (28 ng/mL versus 34 ng/mL; = 0.016), and EPT children were more likely to receive multivitamin supplementation before admission. Vitamin D levels in children born prematurely, admitted to the PICU, were lower than in controls. Overall levels were lower in LPT infants and this group did not receive multivitamin supplementation as much as those considered EPT. Prior research has shown associations between low vitamin D levels and respiratory disease. To our knowledge, this is the first study showing an association between low vitamin D levels and severity of respiratory disease, specifically in preterm children. Further, we found that late preterm children have lower levels of vitamin D and less frequent multivitamin supplementation.