Vitamin D in Term Newborns: Relation with Maternal Concentrations and Birth Weight

To evaluate vitamin D serum levels of term newborns and relate them to maternal concentrations and birth weight.

Cross-sectional study carried out with 225 mothers and their term newborns. Data collected were maternal health, prenatal care, gestational, and anthropometric data of the newborns. The following laboratory tests were performed: serum levels of 25(OH)D, calcium, phosphorus, magnesium, and alkaline phosphatase.

Of the 225 newborns included in the study, 119 (52.9%) were males, the mean birth weight was 3,198 ± 421.4 g, and the gestational age was 39.1 ± 1.1 weeks. Of these, 20 (8.9%) were small and 12 (5.3%) were large for gestational age. A 25(OH)D sufficiency was found in 25.8% of mothers and 92% of newborns. The mean 25(OH)D concentrations of newborns was higher than that of the mothers 48.7 ± 15.2 ng/mL vs. 26.0 ± 6.7 ng/dL (p < 0.001), correlating inversely with birth weight (r = -0.249; p < 0.001). Small for gestational age (SGA) newborns had higher concentrations of 25(OH)D compared to adequate and large for age (p < 0.001).

In conclusion, this study showed strong positive correlation between maternal and neonatal 25(OH)D concentrations, with higher values in newborns. The highest 25(OH)D concentrations were found in SGA term infants. We speculated these findings could be influenced by newborn body composition.