Vitamin D-deficient newborns more susceptible to respiratory infections

Neonates who are vitamin D-deficient at birth may have increased risk of developing respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) during their first year of life, according to a study in Pediatrics.

Although more than 90% of infants encounter RSV before the age of 2 years, only 10% develop severe LRTI, with the majority of severe infections occurring without any known risk factors. Previous research suggested that cord blood vitamin D concentration might protect infants against RSV LRTI.

In a prospective birth cohort study of 156 neonates in the Netherlands, data revealed that 18 newborns found to have low concentrations of 25-hydroxyvitamin D (25-OHD) in their cord blood plasma developed RSV LRTI in the first year. Overall, 27% of the study population had 25-OHD concentrations of less than 50 nmol/L; 27% had concentrations of 50 nmol/L to 74 nmol/L; and 46% had concentrations of 75 nmol/L or higher. Mean plasma 25-OHD concentration among healthy newborns was 82 nmol/L.

In total, 54% of participating women used vitamin D supplements throughout their pregnancies and cord blood 25-OHD concentrations in neonates were strongly associated with vitamin D supplements taken by their mothers during pregnancy. Those neonates born with 25-OHD concentrations of less than 50 nmol/L were 6 times more likely to develop RSV LRTI than those with concentrations of 75 nmol/L or higher.

Researchers conclude that “increased awareness of vitamin D status of pregnant women and intensified routine vitamin D supplementation may help prevent RSV LRTI during infancy.” Because the optimal dose of vitamin D supplementation is still under debate, they suggest that more randomized trials should address this question.

Belderbos ME, Houben ML, Wilbrink B, et al. Cord blood vitamin D deficiency is associated with respiratory syncytial virus bronchiolitis. Pediatrics. 2011;127(6):e1513-e1520.