Is there a potential link between vitamin D and pulmonary morbidities in preterm infants?

Background: There hasn't been conclusive proof about the association between vitamin D and pulmonary morbidities of prematurity.

Methods: 106 preterm infants were retrospectively included into this study. Clinical data and blood samples of all the patients were collected within 24 h of admission.

Results: (1) Respiratory distress syndrome (RDS) patients were mainly concentrated in "≤30 weeks" stage when compared with other two gestational age groups. The only significant decrease of vitamin D concentration between RDS and non-RDS patients reflected in "≤30 weeks" stage (RDS vs. non-RDS: 29.48 ± 13.06 vs. 40.47 ± 20.52 nmol/l). (2) Bronchopulmonary dysplasia (BPD) patients were also concentrated in "≤30 weeks" stage. Vitamin D concentration showed significant difference both in "≤30 weeks" stage and "30-34 weeks" stage (≤30 weeks stage, BPD vs. non-BPD: 33.20 ± 16.51 vs. 39.21 ± 16.65 nmol/l; 30-34 weeks stage, BPD vs. non-BPD: 30.36 ± 15.50 vs. 41.21 ± 20.40 nmol/l). (3) Though vitamin D concentration in mechanical ventilation (MV) group was lower than non-MV group, there're no significant differences. (4) Vitamin D concentration in dead cases was significant lower than survival patients at discharge. (5) It showed a good correlation between vitamin D concentration and serum Ca, serum P, duration of MV and duration of oxygen support in "≤30 weeks" stage.

Conclusion: The significant decrease of vitamin D concentration between RDS and non-RDS patients only reflected in "≤30 weeks" stage. And significant decrease of vitamin D concentration in BPD patients was both showed in "≤30 weeks" stage and "30-34 weeks" stage, which is consistent with "duration of oxygen support". However, the overall effect did not show any difference in all preterm infants. It seems that the appropriate concentration of vitamin D is beneficial to lung maturation of human. Certainly, large sample, multi-center randomized controlled trials are necessary.