Breastfeeding is the most efficient intervention for reducing infant morbidity and mortality, offering benefits for both infants and mothers. Despite extensive promotion, global adherence remains below 50 %. Breastfeeding offers numerous benefits for both infants and mothers, including providing optimal nutrition and immunological protection for the baby and reducing the risk of certain diseases for the mother.
Human milk is the most appropriate source of nutrients and bioactive compounds for newborns, supporting their psycho-emotional development. This biological fluid plays a crucial role in the health of both infants and mothers, with positive outcomes throughout their lifespans. Experts agree breastfeeding should be exclusive for the first six months and mixed until at least two years of age. Children who are breastfed for longer periods show lower morbidity and mortality from infectious diseases, dental issues, long-term obesity, and diabetes, as well as better cognitive development Additionally, breastfeeding benefits maternal health, acting as a protective factor against oncological, metabolic, cardiovascular, and neurodegenerative diseases later in life.
Breast milk contains all the nutrients that an infant needs in the first 6 months of life, including fat, carbohydrates, proteins, vitamins, minerals and water. It is easily digested and efficiently used. Breast milk also contains bioactive factors that augment the infant’s immature immune system, providing protection against infection, and other factors that help digestion and absorption of nutrients.
Breast milk contains many factors that help to protect an infant against infection including:
- immunoglobulin, principally secretory immunoglobulin A, which coats the intestinal mucosa and prevents bacteria from entering the cells.
- white blood cells which can kill micro-organisms.
- whey proteins (lysozyme and lactoferrin) which can kill bacteria, viruses and fungi.
- oligosaccharides which prevent bacteria from attaching to mucosal surfaces.
The protection provided by these factors is uniquely valuable for an infant. First, they protect without causing the effects of inflammation, such as fever, which can be dangerous for a young infant. Second, Immunoglobulin A contains antibodies formed in the mother’s body against the bacteria in her gut, and against infections that she has encountered, so they protect against bacteria that are particularly likely to be in the baby’s environment.
Bile-salt stimulated lipase facilitates the complete digestion of fat once the milk has reached the small intestine. Fat in artificial milks is less completely digested. Epidermal growth factor stimulates maturation of the lining of the infant’s intestine, so that it is better able to digest and absorb nutrients and is less easily infected or sensitized to foreign proteins. It has been suggested that other growth factors present in human milk target the development and maturation of nerves and the retina.
Colostrum is the special milk that is secreted in the first 2–3 days after delivery. It is produced in small amounts, about 40–50 ml on the first day but that is all an infant normally needs at that time. Colostrum is rich in white cells and antibodies, especially immunoglobulin A, and it contains a larger percentage of protein, minerals and fat-soluble vitamins (A, E and K) than later milk. Vitamin A is important for protection of the eye and for the integrity of epithelial surfaces and often makes the colostrum yellowish in color. Colostrum provides important immune protection to an infant when he or she is first exposed to the micro-organisms in the environment, and epidermal growth factor helps to prepare the lining of the gut to receive the nutrients in milk. It is important that infants receive colostrum, and no other feeds, at this critical time.
Milk starts to be produced in larger amounts between 2 and 4 days after delivery, making the breasts feel full; the milk is then said to have “come in”. On the third day, an infant is normally taking about 300–400 ml per 24 hours, and on the fifth day 500–800 ml. From day 7 to 14, the milk is called transitional, and after 2 weeks it is called mature milk. Nature in its wisdom adapts milk to the needs of the infant as he or she matures.
Infant formula is usually made from industrially modified cow milk or soy products. During the manufacturing process the quantities of nutrients are adjusted to make them more comparable to breast milk. However, the qualitative differences in the fat and protein cannot be altered, and the absence of anti-infective and bio-active factors remain. Powdered infant formula is not a sterile product and may be unsafe in other ways. Life threatening infections in newborns have been traced to contamination with pathogenic bacteria, such as Enterobacter, found in powdered formula. Soy formula contains phytoestrogens, with activity like the human hormone estrogen, which could potentially reduce fertility in boys and bring early puberty in girls.
Mother nature thinks of everything. Milk production is controlled in the breast by a substance called the feedback inhibitor of lactation, or FIL (a polypeptide), which is present in breast milk. Sometimes one breast stops making milk while the other breast continues, for example if a baby suckles only on one side. This is because of the local control of milk production is independent within each breast. If milk is not removed, the inhibitor collects and stops the cells from secreting any more, helping to protect the breast from the harmful effects of being too full. If breast milk is removed the inhibitor is also removed, and secretion resumes. If the baby cannot suckle, then milk must be removed by expression.
FIL enables the amount of milk produced to be determined by how much the baby takes, and therefore by how much the baby needs. This mechanism is particularly important for ongoing close regulation after lactation is established. At this stage, prolactin a pituitary hormone that plays a key role in milk production is needed to enable milk secretion to take place, but it does not control the amount of milk produced, the infant does.
The baby’s reflexes are important for appropriate breastfeeding. The main reflexes are rooting, suckling and swallowing. When something touches a baby’s lips or cheek, the baby turns to find the stimulus, and opens his or her mouth, putting his or her tongue down and forward. This is the rooting reflex and is present from about the 32nd week of pregnancy. When something touches a baby’s palate, he or she starts to suck it. This is the sucking reflex. When the baby’s mouth fills with milk, he or she swallows. This is the swallowing reflex. Preterm infants can grasp the nipple from about 28 weeks gestational age, and they can suckle and remove some milk from about 31 weeks. Coordination of suckling, swallowing and breathing appears between 32 and 35 weeks of pregnancy. Infants can only suckle for a short time at that age, but they can take supplementary feeds by cup. Most infants can breastfeed fully at a gestational age of 36 weeks.
Babies feed with different frequencies and take different amounts of milk at each feed. The 24-hour intake of milk varies between mother-infant pairs from 440–1220 ml, averaging about 800 ml per day throughout the first 6 months. Infants who are feeding on demand according to their appetite obtain what they need for satisfactory growth. They do not empty the breast but remove only 63–72% of available milk. More milk can always be removed, showing that the infant stops feeding because of satiety, not because the breast is empty……. Nature thinks of everything.
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