Incidence and predictors of high vitamin D in premature infants with very low birth weight.

OBJECTIVES

To examine the incidence of hypervitaminosis D in very low birth weight (VLBW) infants and any associated maternal or neonatal factors.

METHODS

In this single center retrospective study, we studied serum vitamin D (25[OH]D) levels, maternal and neonatal demographic and clinical factors. We included VLBW infants (≤32 weeks gestational age (GA) and ≤1,500 g birthweight, n = 130) born between 2021 and 2023. VLBWs receive 400 IU/day cholecalciferol once TPN is discontinued. Hypervitaminosis D was defined as 25[OH]D levels >60 ng/mL. We considered 11 variables with plausibility to influence this outcome. Variables with p < 0.20 in univariate logistic regression were entered into a multivariable logistic model to assess associations with the primary outcome. A linear mixed model assessed the association between calcium and 25[OH]D levels, with time as a fixed effect and subject as a random effect.

RESULTS

63 VLBWs (48 %) developed hypervitaminosis D. Maternal age > 35 years (OR = 2.2, 95 % CI 0.96-5.06) associated with excess 25[OH]D approached statistical significance (p = 0.06). 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.

CONCLUSIONS

25[OH]D supplementation of 400 IU/day in VLBWs is associated with a high incidence of hypervitaminosis D. The above findings reveal a significant effect of maternal demographic and clinical factors on newborn metabolic health. Further work is needed to identify causes of hypervitaminosis D. Long term prospective studies are needed to understand the impact of hypervitaminosis D in VLBWs.