Resident Donald and Barbara Zucker School of Medicine at Hofstra/Northwell Staten Island, New York, United States
Background: Preterm infants are at increased risk of metabolic bone disease. In current clinical practice, preterm infants receive supplemental vitamin D. Evidence regarding normative therapeutic vitamin D levels in this population is limited. A vitamin D level screening program among very low birth weight (VLBW) infants in our Level 3 NICU revealed multiple patients with hypervitaminosis D. Objective: To examine the incidence of hypervitaminosis D in preterm VLBW infants and any associated maternal or neonatal factors. Design/Methods: In this single center retrospective study, we studied vitamin D levels and demographic and clinical factors possibly affecting levels in VLBWs. We included preterm VLBW infants (≤ 32 weeks gestational age (GA) and ≤ 1500 g birthweight, n=130) born between 2021 and 2023. By protocol, infants in our NICU receive 400 IU/day vitamin D. Hypervitaminosis D was defined as vitamin D levels greater than 60 ng/ml at any point during hospital stay. Statistical analysis was performed via t-tests, Mann Whitney U tests, chi-square tests and linear regression. We considered 11 variables with plausibility to influence this outcome, and variables with p< 0.20, based on a univariate logistic regression, were included in a multivariable logistic model to assess their associations with the primary outcome. Results: Out of 130 eligible infants, 60 infants (46.15%, 95% CI: 37.38%-55.11%) had excess vitamin D during their hospital stay. Maternal age > 35 years (OR=2.2, 95% CI 0.96-5.06) was associated with excess vitamin D. Our findings indicate that in GA ≥ 28 weeks (OR=0.77, 95% CI 0.64-0.92) and maternal hypertension (OR=0.32, 95% CI 0.14-0.73) were associated with reduced likelihood of hypervitaminosis D.
Conclusion(s): The standardized use of vitamin D supplementation at 400 IU/day in VLBWs is associated with a high incidence of hypervitaminosis D. The above findings reveal the significance of maternal factors on newborn health following birth. Further research should examine causative factors resulting in high vitamin D levels. Long term prospective studies are needed to understand the impact of hypervitaminosis D in this patient population.
