# Short-term and long-term effects of vitamin D supplementation for preterm infants: a systematic review and meta-analysis

## TL;DR

This study finds that high-dose vitamin D supplementation improves short-term health outcomes in preterm infants, with 800 IU/day being the most effective dose.

## Contribution

The study identifies optimal vitamin D dosage for preterm infants and evaluates short-term and long-term effects using a systematic review and meta-analysis.

## Key findings

- High-dose vitamin D supplementation increases serum 25(OH)D levels and reduces vitamin D deficiency in preterm infants.
- 800 IU/day of vitamin D is more effective than 400 IU/day in improving short-term outcomes without causing vitamin D excess.
- Long-term outcomes show no significant differences between high-dose and low-dose vitamin D supplementation.

## Abstract

Meta-analysis conducted to evaluate the effectiveness of high-dose (≥800 IU/day) and low-dose (<800 IU/day) vitamin D supplementation on preterm infants. Study quality was evaluated using the Revised Cochrane risk-of-bias tool 2 for randomized trials. 21 studies included 1130 infants. Regarding short-term (before 40 weeks’ postmenstrual age [PMA] or at discharge) outcomes, high-dose vitamin D supplementation was associated with increased serum 25-hydroxyvitamin D (25[OH]D) levels (mean difference 15.62 [13.35–17.88]) and growth velocities, as well as decreased vitamin D deficiency (VDD), skeletal hypomineralization, and mortality. In the subgroup analysis of high-dose supplementation stratified by dosage, 800 IU/day significantly increased serum 25(OH)D levels (mean difference 13.99 [9.03–18.95]) and reduced the risk of VDD (risk difference −0.21 [−0.32 to −0.10]) compared to 400 IU/day, without increasing the risk of vitamin D excess. The long-term outcomes assessed after 40 weeks’ PMA or at follow-up visits showed no significant differences in vitamin D status or neurodevelopmental outcomes between the high-dose and low-dose groups. The certainty of the evidence ranges from moderate to very low. High-dose vitamin D supplementation improved short-term outcomes by increasing serum 25(OH)D levels, promoting growth, and reducing mortality. Among the high-dose regimens, 800 IU/day appeared to be the most appropriate dose.