[Vitamin D level in umbilical cord blood of late preterm infants and the effect of vitamin D 3 supplementation on the behavioral development of infants and young children: a prospective randomized controlled study].

Objectives: To investigate the level of 25 hydroxyvitamin D [25(OH)D] in late preterm infants and the effect of vitamin D ₃ supplementation on the neurobehavioral development of infants and young children.
Methods: In this prospective study, 161 late preterm infants who were admitted from June 2017 to June 2020 were enrolled. According to the level of 25(OH)D in umbilical cord blood, they were divided into three groups: sufficiency group ( n =52), insufficiency group ( n =53), and deficiency group ( n =56). Each group was further divided into subgroup A (vitamin D ₃ 800 IU/d) and subgroup B (individualized vitamin D ₃ supplementation) using a random number table. The levels of 25(OH)D were measured at 3 months after birth and at the corrected ages of 10 months and 18 months. The neurobehavioral development levels were determined by the Gesell Developmental Scale at the corrected ages of 10 months and 18 months.
Results: Within 24 hours and 3 months after birth, the insufficiency group and the deficiency group had a significantly lower level of 25(OH)D than the sufficiency group ( P <0.05), and the insufficiency group had a significantly higher level of 25(OH)D than the deficiency group ( P <0.05). In the deficiency group, subgroup B had a significantly higher level of 25(OH)D than subgroup A ( P <0.05) at 3 months after birth. At the corrected ages of 10 months and 18 months, the insufficiency and deficiency groups had significantly lower scores of five functional areas of the Gesell Development Scale than the sufficiency group ( P <0.05). Compared with the insufficiency group, the deficiency group had a significantly lower score of language at the corrected age of 10 months and a significantly lower score of gross motor at the corrected age of 18 months ( P <0.05). Compared with subgroup A of the deficiency group, subgroup B had a significantly higher score of adaptive ability at the corrected age of 10 months and significantly higher scores of adaptive ability and response ability at the corrected age of 18 months ( P <0.05).
Conclusions: There is a significant difference in the level of 25(OH)D in umbilical cord blood in late preterm infants. Individualized vitamin D supplementation appears to be more effective for the treatment of vitamin D deficiency. Vitamin D level at birth and in early infancy has certain influence on neurobehavioral development.