OBJECTIVE. We aimed to provide information that can be used as a guide to clinicians when advising breastfeeding mothers on normal lactation with regard to the frequency and volume of breastfeedings and the fat content of breast milk.METHODS. Mothers (71) of infants who were 1 to 6 months of age and exclusively breastfeeding on demand test-weighed their infants before and after every breastfeeding from each breast for 24 to 26 hours and collected small milk samples from each breast each time the infant was weighed.RESULTS. Infants breastfed 11 Ϯ 3 times in 24 hours (range: 6 -18), and a breastfeeding was 76.0 Ϯ 12.6 g (range: 0 -240 g), which was 67.3 Ϯ 7.8% (range: 0 -100%) of the volume of milk that was available in the breast at the beginning of the breastfeeding. Left and right breasts rarely produced the same volume of milk. The volume of milk consumed by the infant at each breastfeeding depended on whether the breast that was being suckled was the more or less productive breast, whether the breastfeeding was unpaired, or whether it was the first or second breast of paired breastfeedings; the time of day; and whether the infant breastfed during the night or not. Night breastfeedings were common and made an important contribution to the total milk intake. The fat content of the milk was 41.1 Ϯ 7.8 g/L (range: 22.3-61.6 g/L) and was independent of breastfeeding frequency. There was no relationship between the number of breastfeedings per day and the 24-hour milk production of the mothers.CONCLUSIONS. Breastfed infants should be encouraged to feed on demand, day and night, rather than conform to an average that may not be appropriate for the mother-infant dyad. REASTFEEDING MOTHERS SHOULD be made aware of the variability of milk volumes per breastfeeding, the frequencies of breastfeedings, and the distribution of milk intake by day and by night of healthy breastfed infants. 1 Mothers among the !Kung hunter-gatherers have been observed to breastfeed 4 times every hour during the day and at least once at night. 2 In contrast, Cadogan,3 in his essay to the Governors of the Foundling Hospital (London, United Kingdom) in 1748 recommended that infants be suckled only 4 times a day and not at night, because he considered the night feeding to result in breastfed infants' becoming "over fat and bloated." Relaxation of the concept of scheduled breastfeeding was first strongly promoted by Wickes 4 in 1953 and subsequently advocated by community support groups such as La Leche League and the Australian Breastfeeding Association that were at the vanguard of the movement back to breastfeeding in the early 1970s in Western societies. As a result, infants were breastfed more frequently both by day and by night. It now is recognized that breast milk provides the optimal nutrition for infants, and current recommendations to mothers are that infants be breastfed "on demand" (according to their appetite) exclusively for the first 6 months of life. 5,6 Bangladeshi infants have been found to consume half their daily milk ...

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Fat in human milk is extremely variable and can represent up to 50 % of infant energy intake. To accurately determine milk composition and infant intake at 1 (n 17), 2 (n 17), 4 (n 17), 6 (n 15), 9 (n 6) and 12 (n 5) months of lactation, samples of fore-and hind-milk were collected from each breast at each feed over 24 h periods from an initial group of seventeen women. The content of fat in milk varied over 24 h, with a mean CV of 47·6 (SE 2·1) % (n 76) and 46·7 (SE 1·7) % (n 76) for left and right breasts respectively. The 24 h amounts of fat, lactose and protein in milk differed between women (P¼0·0001), but were consistent between left and right breasts. Daily milk production differed between breasts (P¼0·0001) and women (P¼ 0·0001). Accordingly, amounts of fat (P¼0·0008), lactose (P¼0·0385) and protein (P¼0·0173) delivered to the infant over 24 h also differed between breasts and women (P¼0·0001). The energy content of milk and the amount of energy delivered to the infant over 24 h were the same between breasts, but differed between women (P¼ 0·0001). The growth rate of a group of only six infants in the present study was not related to either the concentrations or amounts of fat, lactose, protein and energy in milk over the first 6 months of life. These results show the individuality of milk composition and suggest that only a rigorous sampling routine that takes into account all levels of variation will allow the accurate determination of infant intake of fat, lactose, protein and energy.Milk fat: Infant intake: Sampling routine: Human lactation Of the major digestible energy components (fat, lactose and protein) in human milk, fat is the most variable. Woolridge (1995) listed several factors that either individually or in concert could account for the variability in fat content of human milk. Major factors included the amount of milk removed at both the last and current breast-feed, the length of the interval between breast-feeds, and the fat content at the end of the last breast-feed. Daly et al. (1993a ) showed that approximately 70 % of the variation in fat content of breast milk was due to the extent of fullness of the breast (see Cox et al. 1996), essentially incorporating all the predictors proposed by Woolridge (1995) and expressing them as one term. Furthermore, the discovery of local (autocrine) control systems for milk synthesis (Henderson & Peaker, 1984) and possibly milk-fat synthesis (Heesom et al. 1992), combined with differences in milk production and storage capacity between breasts within mothers (Daly et al. 1993a), could result in different rates of milk and fat synthesis between breasts. These factors make it difficult to design a sampling protocol, suitable for all women, that will provide a true indication of energy density and intake of breast milk without affecting the natural routine of the demand-fed infant (Prentice & Prentice, 1988;Lucas & Davies, 1990;Prentice et al. 1996).We have used a sampling protocol similar to that of Hartmann et al. (1986) that takes into account chang...

Stem cells in mammary tissue have been well characterised by using the mammary stem cell marker, cytokeratin (CK) 5 and the mature epithelial markers CK14, CK18 and CK19. As these markers have never been reported in cells from breastmilk, the aim of this study has been to determine whether mammary stem cells are present in expressed human breastmilk. Cultured cells from human breastmilk were studied by using immunofluorescent labelling and reverse transcription/polymerase chain reaction (RT-PCR). We found a heterogeneous population of cells with differential expression of CK5, CK14, CK18 and CK19. Further, by using the multipotent stem cell marker, nestin, we identified cells in culture that were positive only for nestin or double-positive for CK5/nestin, whereas no co-staining was observed for CK14, CK18 and CK19 with nestin. When cells isolated from breastmilk were analysed by using RT-PCR prior to culture, only nestin and CK18 were detected, thereby indicating that breastmilk contained differentiated epithelial and putative stem cells. Furthermore, fluorescence-activated cell-sorting analysis demonstrated, in breastmilk, a small side-population of cells that excluded Hoechst 33342 (a key property of multipotent stem cells). When stained for nestin, the cells in the side-population were positive, whereas those not in the side-population were negative. The presence of nestin-positive putative mammary stem cells suggests that human breastmilk is a readily available and non-invasive source of putative mammary stem cells that may be useful for research into both mammary gland biology and more general stem cell biology.

This study evaluated the longitudinal effect of fish oil in pregnancy on breast milk fatty acid composition and infant outcomes. In a randomized, controlled trial, 98 women received 2.2 g docosahexaenoic acid (DHA) and 1.1 g eicosapentaenoic acid (EPA) or olive oil from 20 wk of gestation until delivery. Fatty acid composition in breast milk (at 3 d, 6 wk, and 6 mo) and infant erythrocyte membranes (at 1 y) were determined by gas liquid chromatography. Breast milk fatty acids were examined in relationship to growth and development. Compared with control group, breast milk from women who received fish oil had proportionally higher DHA and EPA levels at 3 d and 6 wk after delivery, but this difference was no longer apparent by 6 mo. Infant DHA status at 1 y of age was directly related to DHA levels at 3 d, 6 wk, and 6 mo postpartum (but not to antenatal supplementation). Both EPA and DHA in breast milk were positively correlated with Griffith's developmental scores including hand and eye coordination. Thus, supplementation in pregnancy was associated with increased n-3 long-chain polyunsaturated fatty acids (LCPUFAs) in breast milk, particularly in early lactation, and this was positively associated with infant DHA status at 1 y. (Pediatr Res 62: 689-694, 2007)