Breast-milk composition in women with cystic fibrosis: report of two cases and a review of the literature.

Breast milk was collected from two women with cystic fibrosis (CF) and data from the literature was reviewed. The sodium concentration was within normal limits, 11-24 mmol/L in colostrum and 7-8 mmol/L in mature milk. Normal physiologic changes in milk composition after parturition (decreases in Na and increases in lactose) and during individual feeding periods (increases in fat and decreases in protein) were observed. Concentrations of milk protein, fat, and sugars were normal when the pulmonary disease of these patients was mild. During exacerbations of pulmonary disease, the concentrations of milk macronutrients were reduced. Milk secreted by women with CF appears to be physiologically normal, safe for the infant, and breast-feeding by mothers with CF should no longer be discouraged. Variations in the macronutrient content of CF milk warrants routine monitoring of the mother with CF and the breast-fed infant, especially during exacerbations in the pulmonary aspects of this disease.