Vitamin D status of very low birth weight infants at birth and the effects of generally recommended supplementation on their vitamin D levels at discharge.

To evaluate vitamin D status in mothers and their very low birth weight infants (VLBW) at birth (umbilical cord blood) and at discharge with currently recommended supplementation of vitamin D. Ninety-four infants with birth weight less than 1500 g completed the study. The total daily vitamin D intake was 800-1000 IU. We examined 25-hydroxyvitamin-D [25(OH)D] levels in maternal serum before labor, in cord blood, and in infants' serum at discharge. Median (IQR) serum 25(OH)D was 21 (14-36) nmol/l [8 (6-15) ng/ml] in cord blood, and 46 (37-60) nmol/l [18 (15-24) ng/ml] at discharge. Serum 25(OH)D was <50 nmol/L in 71.3% of mothers, in 91.5% of cord blood samples, and in almost 60% of preterm newborns at discharge (after 8 weeks of supplementation). Serum 25(OH)D was <75 nmol/L in 88.3% of mothers, in 97.9% of cord blood samples, and in 91.4% of preterm newborns at discharge. In our cohort, we found that due to the very high prevalence of 25(OH)D deficiency among mothers, the current generally recommended dose of vitamin D (800-1000 IU per day) for VLBW infants was unable to improve vitamin D levels above the desired 50 or even 75 nmol/L before discharge.