High Initial Dose of Monitored Vitamin D Supplementation in Preterm Infants (HIDVID Trial): Study Protocol for a Randomized Controlled Study

Vitamin D deficiency can escalate prematurity bone disease in preterm infants and negatively influence their immature immunology system. Infants born at 24 + 0/7 weeks to 32 + 6/7 weeks of gestation will be considered for inclusion. Cord or vein blood samples will be obtained within 48 h after birth for 25-hydroxyvitamin D level measurements. Parathyroid hormone and interleukin-6 levels will be measured. Infants will be randomized to the monitored group (i.e., an initial dose of 1000 IU/day and possible modification) or the controlled group (i.e., 250 IU/day or 500 IU/day dose, depending on weight). Supplementation will be monitored up to a postconceptional age of 35 weeks. The primary endpoint is the percentage of infants with deficient or suboptimal 25-hydroxyvitamin D levels at 28 ± 2 days of age. 25-Hydroxyvitamin D levels will be measured at postconceptional age 35 ± 2 weeks. Secondary goals encompass assessing the occurrence of sepsis, osteopenia, hyperparathyroidism, and interleukin-6 concentration. The aim of this study is to evaluate the efficacy of monitored vitamin D supplementation in a group of preterm infants and ascertain if a high initial dosage of monitored vitamin D supplementation can decrease the occurrence of neonatal sepsis and metabolic bone disease.

Benefits of prenatal and postnatal vitamin D supplementation

The best evidence for the role of vitamin D in infants is its influence on skeletal growth, however, the pleiotropic actions of vitamin D in the foetus and neonates are under-researched. The systematic reviews, based mostly on observational studies, suggest correlations between prenatal and postnatal supplementation and the occurrence of allergy, respiratory infections, sepsis or mental and behavioural development. Some of these studies focused on subgroups of neonates, such as preterm infants, investigating the influence inter alia on sepsis, bronchopulmonary dysplasia, and necrotising enterocolitis. Currently, there is a need for randomised trials for proof of the skeletal and pleiotropic effects of vitamin D in infants.