Mature human milk
aCow’s milk
bInfant formula
cEnergy (kJ) 2,929 2,930 2,500–3,550 Energy (kcal) 700 700 597–848 Protein (g) 10.3 35 11–24.8 Fat (g) 43.8 35 26–53 Carbohydrate (g) 68.9 63 72–75 Sodium (mg) 170 370 125–532 Calcium (mg) 320 1070 min 300 Phosphorus (mg) 140 920 150–887 Iron (mg) 0.3d negligible 5–17.7e Vitamin A (mcg) 610 530 350–1526
Vitamin C (mg) 50 negligible min 42.5
Vitamin D (mcg) 1.0 5.2 6.25–22.3
Potassium (mg) 510 1420 500–1775
a. Us department of Agriculture (UsdA) national nutrient database for standard Reference 2011.195
b. Regular fat (~3.5%) cow’s milk. nutrient tables for Use in Australia (nUttAB) 2010.196
c. Ranges for infant formula products (from birth, cow’s milk–based) based on the regulatory minimum and, where given, maximum range permitted. Adapted from: FsAnZ code standard 2.9.1.197
d. Iron in breast milk is highly bioavailable, with absorption of 50–70%.
e. the bioavailability of iron in infant formula is around 10%, so formulas are fortified to account for this fact.
Human breast milk has a characteristic opalescent appearance. Breast milk has a high water content that meets all the infant’s fluid requirements for at least 6 months, so no additional fluids are required during this time even in hot climate. Breast milk’s whiteness comes from its fat content. the slower the milk flows, the higher the fat content, making it whiter in appearance. It is misleading to describe breast milk as ‘thin’ or ‘watery’ as it contains the same energy and total solids content as cow’s milk.
the increase in the fat content as milk is withdrawn from the breast is a feature of mammalian lactation.
much emphasis has been given to the significance of this change for an infant’s energy intake, but the physiology of milk synthesis, secretion and removal is not fully understood. there are only two ways a breastfed infant can obtain a higher energy intake over a 24-hour period – if the mother produces more milk, or if the mother produces the same volume of milk with a higher fat content. since animal studies demonstrate that it is difficult to alter the average daily composition of milk, it is not surprising that research shows that variations in the intervals between breastfeeds and in the amount of milk withdrawn during a breastfeed explain only a small proportion (20–26%) of the variation in the fat content of breast milk.198,199 the degree of breast emptying explains changes in the fat
content, but not the fatty acid composition of human milk.198
A factor determining the fat content of breast milk is the fullness of the breast. the first milk withdrawn from a full breast has a low-fat content, with fat content rising more rapidly after the removal of about 40% of the breast’s storage capacity. depending on both the fullness and the storage capacity of the mother’s breasts, the fat content at the end of one breastfeed (the hind milk) may be either lower or higher than that at the beginning (the fore milk) of a subsequent breastfeed.57,198
colostrum, which is produced during late pregnancy and for the first 30–40 hours after birth, is yellowish and thicker than mature milk and contains a high concentration of immunoglobulins.164
2.2.6 Individual variation
mothers and infants vary considerably in a range of aspects of breastfeeding.200 the anatomy of the breast varies
greatly between women. some women can store up to six times more milk than other women.200,201 As a result,
women with large storage capacity have great flexibility in their frequency of breastfeeding, while women with a smaller storage capacity need to feed more frequently to maintain similar levels of milk production. this latter group should spread breastfeeds fairly evenly over the 24-hour cycle. this highlights the importance of infant-led feeding – allowing the infant to regulate intake according to need. It also shows the value of letting the infant ‘finish’ the feed in his/ her own time, not according to the clock.
Apart from storage capacity, there is considerable variability in the rate of milk flow, the nature of mouth–breast positioning, and changes in milk composition during a feed.
Infants’ milk intake varies, with average intakes of exclusively breastfed infants ranging from 710 g/day for the first 2 months to 900 g/day at 9–11 months of age. For partially breastfed infants, average intake decreases from 640–687 g/day at birth to 5 months of age to 436–448 g/day after 9 months of age.
Advice should be tailored to each mother and her infant’s circumstances, rather than imposing arbitrary rules on timing and positioning.202
2.2.7 Positioning and attachment at the breast: the key to successful
breastfeeding
An infant’s ‘milking’ of the breast is dependent on two things:
• attachment to sufficient breast tissue, the tongue positioned forward over the lower gum-line and sufficient vacuum within the intra-oral space
• correct positioning at the breast and correct latching-on and milking action. Table 2.2: Correct positioning during breastfeeding
• The mother should be seated comfortably in an upright position, so that her breasts fall naturally and she has good support for her back, arms and feet
• The infant should be unwrapped to allow easy handling and avoid overheating • A semi-recumbant position can also be used while breastfeeding203
• If the nipple is erect, support the outer area of the breast with a ‘C’ hold, being careful not to alter the breast position • If the nipple is flat or inverted, move the ‘C’ hold under the breast and shape the breast between the thumb and index finger,
well back from the areola
• The infant should be supported behind the shoulders and facing the mother, with his or her body flexed around the mother’s body – the position must be a comfortable drinking position for the infant
• The infant’s nose should be level with the mother’s nipple, and a wide gape should be encouraged by teasing the infant’s mouth with the underside of the areola
• When the infant gapes widely, bring him or her quickly onto the breast so that he or she will take a good mouthful of breast – bring the infant to the breast, not the breast to the infant.
• The chin should be tucked well into the breast, and the infant’s mouth should be wide open, with the bottom lip curled back – more areola will be evident above the infant’s top lip than below the bottom lip
• When positioning is correct it is not necessary to hold the breast away from the infant’s nose
• After an initial short burst of sucking, the rhythm will be slow and even, with deep jaw movements that should not cause the mother any discomfort – pauses are a normal part of the feed and they become more frequent as the feed continues • If the cheeks are being sucked in or there is audible ‘clicking’, the infant is not attached correctly
• The infant should stop feeding of his or her own accord by coming off the breast spontaneously • The nipple will appear slightly elongated but there should be no evidence of trauma
women commonly experience heightened nipple sensitivity and tenderness in the first few days after birth but this usually subsides as breastfeeding becomes established. If nipples are already sore or cracked, and even if positioning and attaching errors are corrected, they may continue to be tender at the start and end of feeds for some time. the mother should be reassured that the discomfort will diminish as the nipples heal and feeding continues. If the infant is correctly positioned and attached and is sucking correctly there should be no nipple pain.
Advice for health workers
• when discussing breastfeeding with women, pay particular attention to the importance of correct positioning and attachment when breastfeeding.
2.2.8 Signs of a functioning milk-ejection reflex
Although some mothers report no noticeable signs of the milk-ejection reflex, many mothers do notice one or more of the following signs:
• tingling or prickling – ‘pins and needles’, which may take several weeks to develop • a sudden feeling of fullness
• an increase in skin temperature • a feeling of wellbeing or relaxation • for some mothers, pain or nausea
• dripping, leaking or spurting from the unsucked breast • for some mothers, an intense thirst
• uterine contractions accompanied by a gush of lochia in the immediate postpartum period – this is more common in women who have had two or more children.
there may also be noticeable changes in the infant’s sucking and swallowing pattern. this sign is more consistent than any of the others, but it may take the mother several days of observation after her milk ‘comes in’ to recognise the changes. there are two types of sucking:
• non-nutritive sucking occurs in short, sharp bursts at a rate of up to two per second • nutritive sucking occurs at a slower rate – about one per second.
once the milk has started to flow, the sucking continues at a regular rate. As the feed progresses, sucking becomes fragmented into bursts, usually separated by pauses of longer duration than are seen in the non-nutritive phase. At the start of each burst there may be two to three fast sucks typical of non-nutritive sucking – termed ‘restart sucking’.
2.3 The first breastfeed
there is evidence that starting to breastfeed within the first hour or so of birth is good for both mother and infant and for continued breastfeeding (evidence grade c).110,123 A successful first breastfeed has a number of positive effects:
• it builds the mother’s confidence in her ability to breastfeed • the infant starts to receive the immunological benefits of colostrum • the infant’s digestion and bowel function are stimulated
• correct sucking at the breast at this stage may avert later sucking difficulties • bonding and attachment between mother and infant are enhanced.
Ideally, uninterrupted skin-to-skin contact should be maintained following birth. common practices such as early weighing, bathing the infant, or passing him or her around should be delayed until later. good antenatal education will help with parents’ expectations in this regard. when the infant indicates an interest in sucking or signs of readiness to feed, the midwife can guide the mother into a comfortable position that will enable the infant to attach correctly.
Unless there is a medical reason (such as prematurity) mother and infant should remain together, so that breastfeeding begins and proceeds according to the infant’s needs – without restriction on the number or length of feeds. However, although early contact between mother and infant is the ideal, when this is not possible it does not preclude successful breastfeeding. In Australia, rates of breastfeeding are similar for infants delivered vaginally or by caesarean section. In many cultures, the mother may not have contact with her infant for many hours, yet successful breastfeeding is almost universal.