Background In developing countries, information is limited on concentration of breastmilk zinc, total amount of zinc transferred to infants through breast milk and whether zinc transfer through breastmilk differs among appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) infants at different times post-partum.
Aims To measure breastmilk and zinc transfer through breastmilk, using deuterium “dose-to-mother” technique, in mothers of AGA and SGA infants.
Methods Forty-six mother-infant pairs were recruited (20 AGA and 26 SGA infants). Each mother-infant pair was studied three times, at 4, 12 and 24 weeks post-partum. In each round, two-week studies of breast milk transfer were carried out, using the deuterium oxide “dose-to-mother” technique. Breast milk samples were collected on days 1 and 5 of each round for milk zinc concentration.
Results Mean (±SD) birth weight and length were 3.02±0.2 kg and 48.2±1.2 cm for AGA infants and 2.34±0.20 kg and 46.2±1.1 cm for SGA infants. Breast milk intake increased gradually with time post-partum, and was marginally greater among AGA infants only at 4 weeks (p=0.06). Breast milk zinc concentration decreased when the infants grow (p<0.001), but differed between neither of the groups. Zinc transfer through breast milk decreased significantly with age in both the groups, but did not differ (p<0.001).
Conclusions Breast milk zinc concentration among Bangladeshi mothers was similar to values reported for women from wealthier countries, and there was no relationship between infant birth weight category and milk zinc concentration or milk zinc transfer.