25-hydroxycholecalciferol serum levels in breast-fed infants.

Serum 25-hydroxycholecalciferol levels were measured longitudinally in a series of breast-feeding mothers and their healthy, term infants for up to 6 months after birth. Although levels both in mothers and infants were lower at 6 weeks' postpartum than at delivery and in cord blood, there was little change thereafter with unsupplemented breast feeding. These findings do not support recommendations for routine supplementation of breast-fed term infants with vitamin D.