[Study on change characters and correlations of iron, zinc and calcium in milk and blood of mother and infant at different stages].

OBJECTIVE: To assess the change characters of mineral status in breast milk and blood of lactating mothers and infants at different postpartum stages, and to analyze the clinic significance of these changes in breastfeeding.

METHODS: 50 mother-infant pairs at 6 weeks postpartum and 50 mother-infant pairs at 3 months postpartum were randomly selected, and the concentration of iron, zinc and calcium in milk and blood of mothers and infants were measured according to flame atomic absorption spectrometry. Compared the disparity of these minerals at different stages, and analyze the correlations of the ones among milk, blood of mothers and infants.

RESULTS: the level of iron and zinc declined through lactation(Fe 0.102 mg/100 g vs 0.0605 mg/100 g, P < 0.05; Zn 0.257 mg/100 g vs 0.171 mg/100 g, P < 0.05). The level of iron ion in blood of infants declined with increasing age (392.45 mg/L vs 356.80 mg/L, P < 0.05). The level of iron, zinc and calcium ion in maternal blood was not associated with these minerals of milk, and separately positively associated with these minerals in blood of infan (r = 0.591, 0.362 and 0.435, P = 0.000, 0.013 and 0.001).

CONCLUSION: The mammary mineral transport is likely an active process, and not apparently associated with maternal mineral status. The decline of milk iron through lactation may be one of the reasons for high prevalence of breast-fed infants' physiologic anemia. Maternal mineral status during pregnancy may have an influence on the mineral levels of infants in early period.