Vitamin D and human lactation.

Circulating serum-25-hydroxyvitamin-D concentration was measured in recently delivered mothers who were breast-feeding and in those who were not. 4-6 weeks' lactation produced no significant change. Basal and 4-6-week values in the breast-feeding group were significantly higher than in those who were not breast-feeding. There was no evidence that lactation was an indication for supplementary vitamin D.