Table 5  Levels of 25-hydroxyvitamin D during pregnancy and in neonates and risk of lower respiratory tract infections (LRTI) in infancy.
Study  Authors  Country  Study Population  Results
Association of subclinical vitamin D deficiency in newborns with acute lower respiratory infection and their mothers.  Karatekin et al., 2009 [145]  Turkey  25 newborns with LRTI admitted to NICU vs. healthy controls  Significantly lower vitamin D levels in affected newborns than in controls.
Cord blood vitamin D deficiency is associated with respiratory syncytial virus bronchiolitis.  Belderbos et al., 2011 [146]  Netherlands  156 healthy newborns  Lower cord blood vitamin D in neonates who developed RSV infections.
Maternal vitamin D status in pregnancy and risk of lower respiratory tract infections, wheezing, and asthma in offspring.  Morales et al., 2012 [147]  Spain  1724 pregnant women  Decreased LRTI in offspring of mothers with higher vitamin D.
Cord blood 25-hydroxyvitamin D levels and the risk of acute lowerrespiratory tract infection in early childhood.  Mohameet al., 2013 [148]  Egypt  206 healthy newborns  Increased risk of developing ALRIs in the first 2 years of life in newborns with lower cord blood vitamin D.
Prospective study of maternal mid-pregnancy 25-hydroxyvitamin D level and earlychildhood respiratory disorders.  Magnus et al., 2013 [149]  Norway  Pregnant women  Reduced risk of LRTI in offspring by age 36 months when maternal vitamin D was higher.
Cord blood 25(OH)D levels and the subsequent risk of lower respiratory tract infections in early childhood: the Ulm birth cohort.  Luczynska et al., 2014 [150]  Germany  777 healthy newborns  Increased risk of developing LRTIs in the first year of life in infants with vitamin D deficiency in cord blood.
Cord blood vitamin D and the risk of acute lower respiratory infection in Indigenous infants in the Northern Territory.  Binks et al., 2016[151]  Australia  109 mother-infant pairs  Higher risk of hospitalization for ALRI in pairs with lower vitamin D levels in pregnancy, cord blood and infants’ blood.
Association of vitamin D deficiency with acute lower respiratory tract infections in newborns.  Dinlen et al., 2016[152]  Turkey  30 newborns with ALRI and their mothers vs. healthy control pairs  Lower vitamin D levels in ALRI group than in healthy controls.
Low cord-serum 25-hydroxyvitamin D levels are associated with poor lung function performance and increased respiratory infection in infancy.  Lai et al., 2017[153]  Taiwan  122 mother-infant pairs  Higher risk of RTI and poorer lung function in infants with lower vitamin D levels (maternal and cord blood).
Vitamin D Status in Neonatal Pulmonary Infections: Relationship to Inflammatory Indicators.  El-Kassas et al., 2019[154]  Egypt  33 neonates with pneumonia vs. healthy controls  Lower levels of vitamin D in pneumonia patients.
ALRI, acute lower respiratory tract infection; LRTI, lower respiratory tract infection; NICU, neonatal intensive care unit; RSV, respiratory syncytial virus; RTI, respiratory tract infection.