Chapter 43 Infant feeding
At the end of this chapter, you will:
Gold standard
Human milk is the gold standard for nutrition of the human infant (Lawrence & Lawrence 2005, NICE 2006). It contains unique constituents valuable for brain growth, such as cholesterol, omega-3 fatty acids and the amino acid taurine, together with immune properties that cannot be matched with any substitutes. It is the standard all health professionals should endeavour to achieve for the neonate, through the information given to women and their families.
In 1989, Protecting, promoting and supporting breastfeeding: the special role of maternity services (WHO/UNICEF 1989) was published. This was adopted as a global initiative by policy makers at a meeting in Florence, now referred to as the Innocenti Declaration (Henschel & Inch 1996). In June 1991, the Baby-Friendly Hospital Initiative (BFHI) was launched at the International Paediatric Association Conference, Ankara, providing a global focus for the intent of the Innocenti Declaration. The principles of the declaration were embodied in the ‘Ten steps to successful breastfeeding’ (Box 43.1), designed as a set of standards that can be followed by maternity units all over the world and audited to demonstrate measurable improvements.
Box 43.1
The ten steps to successful breastfeeding (WHO/UNICEF 1989)
All providers of maternity services should:
The WHO Global Strategy for Infant and Young Child Feeding, incorporating the UNICEF recommendations, was published in 2002. This document represented 2 years of evidence and all previous initiatives and statements calling on governments to fully support breastfeeding (WHO 2002).
Public health issues
The National Service Framework for Children, Young People and Maternity Services recommends all Trusts (hospitals) have minimum standards for breastfeeding, early access to support services and specialist advice (DH 2004a).
NICE postnatal guidelines specify that a written policy for breastfeeding must be available in all healthcare settings and communicated to all staff. A lead healthcare professional must be identified to ensure this is implemented, using the Baby Friendly Initiative as a minimum standard in an environment conducive to breastfeeding (NICE 2006).
Maternity matters (DH 2007a) sets out the DH Policy commitment to maternity services and includes the achievement of the Public Service Agreement (PSA) targets (DH 2007b), namely ‘deliver an increase of 2% points per year in breastfeeding initiation rate, focusing especially on women from disadvantaged groups’. Breastfeeding is a key factor in reducing childhood obesity (Cross Government Obesity Unit 2008, Von Kries et al 1999) and diabetes (CEMACE 2007).
A breastfeeding manifesto was launched in May 2007 by a coalition of 33 UK membership organizations, including all the main Royal Colleges, to improve awareness of the health benefits of breastfeeding and its role in reducing health inequalities across the UK (Breastfeeding Manifesto Coalition 2007). Its guiding principles were for women to feel enabled to initiate and continue breastfeeding for as long as they wish, supported to make informed choices about feeding and ensuring awareness of the significant benefits associated with breastfeeding. See Box 43.2.
Box 43.2
Breastfeeding Manifesto Coalition objectives 2007
As part of the drive to promote breastfeeding, a DVD was developed by Best Beginnings, supported by the DH. This illustrates women discussing the practicalities and benefits of breastfeeding, and is distributed to all pregnant women in the UK (Best Beginnings 2008).
The Healthcare Commission’s review of the maternity services in England recommended Trusts pay particular attention to helping women from minority ethnic groups to maintain breastfeeding (Healthcare Commission 2008).
NICE guidelines on maternal and child nutrition recommend encouraging breastfeeding during the antenatal period and ensuring that women are taught positioning and attachment and to continue breastfeeding for at least 6 months (NICE 2008a).
Midwives should expand their public health role in educating women and their families regarding the value of breastfeeding, and in encouraging women to breastfeed. They can reduce inequalities and social deprivation by working closely with health visitors (HVs) and those specialist nurses providing the Family Nurse Partnership Programme to support women who choose to breastfeed to continue to do so (DH 1999). A multidisciplinary and longsighted approach is required, in line with governments’ public health strategies, that commences preconceptually, and develops and supports women during pregnancy and through into the first few months of the baby’s life.
The full-term neonate – nutritional requirements
Calorific requirements were based traditionally on volumes of formula required by artificially fed babies (Riordan 2008). The calorific requirement for term infants is thought to average 440 kJ per kilogram of body weight per day (110–120 kcal/kg/day) depending on gestational age (Blackburn 2007).
Breast milk (or infant formulae) contains approximately 275 kJ (65 kcal) per 100 mL (Blackburn 2007, Riordan 2008). A baby weighing 3.5 kg requires approximately 1540 kJ in 24 hours – about 525 mL of milk per day. This amount varies depending on the gestation and age of the baby, and volume and content will vary from feed to feed. A meta-analysis of the volume of milk secreted by exclusively breastfeeding women around the world found this to be constant at around 800 mL per day. The volume of milk transferred from the breast to the baby is less than 100 mL per day for the first 24–36 hours, gradually increasing to 500 mL from 36 hours (Neville 1999).
There is no evidence to suggest that healthy term infants require larger volumes of fluid any earlier than they are made available (RCM 2009). The low volume of colostrum is important for optimal physiological adaptation of the neonate, and health professionals need to appreciate that bioavailability of breast milk’s 200 known constituents identifies its superiority over formula milk.
In human milk the calorific value is derived from the carbohydrate and fat content which is absorbed easily through the gut, while cows’ milk has a higher proportion of protein which is less easily digestible. The content of breast milk changes throughout a feed and during the day and night, so can never be directly compared with cows’ milk or formula milk (RCM 2009).
Midwives should be conversant with the relevant DH guidelines (Statutory Instrument 77 1995), information and position statements from the Scientific Advisory Committee on Nutrition (SACN) Subgroup on Maternal and Child Nutrition, its parent body, the Food Standards Agency (FSA), and the WHO Global Strategy on Infant and Young Child Nutrition (WHO 2002).
Physiology of the gastrointestinal tract
The maturation of the neonatal gut is stimulated by initiation of feeding, milk composition, hormonal regulation and genetic encoding (Blackburn 2007). Initiation of early feeding is a major stimulus for the increase of plasma concentrations of peptide hormones, for example, enteroglucagon, which stimulates growth of the intestinal mucosa; gastrin, which stimulates growth of the gastric mucosa and exocrine pancreas; and motilin and neurotensin, which stimulate gut activity. Colostrum stimulates epithelial cell turnover and maturation. Epidermal growth factor and cortisol also assist in the growth and development of the neonatal gastrointestinal system. None of these are available in formula milk.
Until the baby is 9 months old, intake of formula milk stimulates a greater insulin response than intake of breast milk (Blackburn 2007), thus initiating an unnecessary increase in the metabolism of glucose stores.
Normal neonatal metabolism
Protein digestion in the neonate is disadvantaged owing to the limited production of gastric pepsin (a mere trace in some) with pancreatic enterokinase output less than 10% of adults. The ratio of whey to casein proteins in breast milk is more easily digested (Hamosh 1998, Xiao-Ming 2008).
Fat digestion has been shown to be greater in breastfed versus formula-fed preterm neonates (Hamosh 1998). Though the neonate has raised gastric lipase, there is reduced pancreatic lipase for fat digestion. This is compensated by the stimulus of suckling at the breast, stimulating secretion of lingual lipase in the neonate (Blackburn 2007).
Constituents of colostrum and breast milk
Colostrum is produced from 16 weeks’ gestation and continues for the first 3–4 days postpartum, until replaced by milk. It is a yellow-orange, thick sticky fluid that assumes its colour from beta-carotene (Lawrence & Lawrence 2005), with a lower calorific value than breast milk (approx 67 kcal/100 mL versus 75 kcal/100 mL for breast milk).
Transitional breast milk is produced between colostrum (from 3–4 days) and mature milk and lasts for approximately 10 days to 2 weeks postpartum (Lawrence & Lawrence 2005). During this time, protein and immunoglobulin levels decrease while carbohydrate and fat levels increase. Water-soluble vitamins increase and fat-soluble vitamins decrease.
Protein
Approximately 0.9% of breast milk is protein – the more easily digested whey and casein. The ratio is reported to be 9/1 to 6/4 whey/caseins at different lactating periods (Xiao-Ming 2008). Whey is an easily digested antioxidant and can act as an antihypertensive, anticancerous, antiviral, antibacterial and chelating agent (Xiao-Ming 2008). The main components are alpha-lactalbumin, beta-lactoglobulin, serum albumin, immunoglobulins, lactoferrin and lysozyme. Casein constitutes the smaller portion of the protein. In cows’ milk, the protein content is reversed, with an approximately 80% casein to 20% whey ratio (Lawrence & Lawrence 2005). Out of the 20 amino acids present, eight are essential and provide the important nitrogen content required by the neonate. Two of the most abundant amino acids are cystine and taurine. Taurine is absent from cows’ milk but plays an important role in brain maturation and is thought to function as a neurotransmitter. It was originally presumed to be involved only in conjugation of bile acids. Cystine is essential for somatic growth (Riordan 2008).
Carbohydrates
Carbohydrates comprise mainly lactose with small quantities of oligosaccharides, galactose and fructose. Lactose increases calcium absorption and is readily metabolized into galactose and glucose (assisted by the intestinal enzyme lactase), providing the necessary energy to feed the growing brain (Riordan 2008). These levels remain constant and are unaffected in malnourished women (Lawrence & Lawrence 2005).
Some oligosaccharides promote the growth of Lactobacillus bifidus, which increases the acidity of the neonatal gut, protecting it from pathogenic invasion (Kunz et al 1999).
Fats
The fat content varies at different times of the day and during a feed, with higher amounts towards the end of a feed (Kunz et al 1999). Preterm fat concentrations may be 30% higher (Riordan 2008), though others did not detect any major differences in lipid composition between term and preterm breast milk apart from more medium- and intermediate-chain fatty acids (Rodriguez-Palmero et al 1999). Long-chain polyunsaturated fatty acids (LCPUFA) are important for normal visual and brain development and are absent from formula milk. Addition of LCPUFA to formula milk in one very small study was found to improve IQ at 10 months of age (Williatts et al 1998).
The majority of LCPUFA are derived from maternal body stores rather than diet. Maternal diet may directly affect the fatty acid composition of breast milk (Kunz et al 1999, SACN 2007). Vegetarian women are able to maintain a high milk content of arachidonic acid (AA) and docosahexaenoic acid (DHA). DHA is the LCPUFA associated with improved visual and neurological function (Makrides et al 1995, SACN 2007).
Approximately 98% of the fat components are triglycerides that are broken down to fatty acids and glycerol by the enzyme lipase, found in breast milk itself. The remaining fats are phospholipids (0.7%), cholesterol (0.5%) and other lipolysis products. Digestion of triglycerides is initiated in the stomach, where gastric lipase commences lipolysis, and this is continued in the intestine by pancreatic lipase. The resulting monoglycerides have potent bactericidal properties and maintain infection control in the stomach and small intestine (Rodriguez-Palmero et al 1999).
Vitamins
Water-soluble vitamins C (ascorbic acid), B1 (thiamine), B2 (riboflavin and niacin), B6 (pyridoxine), folate (pteroylglutamic acid), B12 (cobalamin), pantothenic acid and biotin are all present in breast milk. Only niacin and B12 can be increased by maternal intake if found to be deficient (Rodriguez-Palmero et al 1999).
Minerals
These include sodium, potassium, chloride, calcium, magnesium, phosphorus, free phosphate and sulphur. Citrate binds some minerals and is soluble in water, so is important though not a mineral. Trace elements such as iron, zinc, copper, manganese, selenium, iodine and fluorine are all present in breast milk, though the latter two are absent from colostrum (Rodriguez-Palmero et al 1999).
The uptake of iron in breast milk is facilitated by the high levels of lactose and vitamin C, enabling up to 70% of absorption to take place. Absorption of exogenous iron from formula milk is limited and can adversely affect the action of lactoferrin from breast milk in the gut if the woman is mixed-feeding (see Table 43.1).
Table 43.1 Defence agents in breast milk (Also see RCM 2009)
| Substance and production | Action |
|---|---|
| 1. Antimicrobial agents | |
| Immunoglobulins | |
| Neonate produces minimal amounts of these in the first few months of life | Proteins produced by plasma cells in response to an antigen – located in the lactoglobulin fraction of breast milk |
| Secretory IgA – most abundant immunoglobulin | Important in providing passive immunity More resistant to proteolytic enzymes Provides resistance to a range of pathogens in gastrointestinal and respiratory tracts Neutralizes viruses and toxins from microorganisms such as Escherichia coli, Salmonella, Clostridium difficile, rotavirus and Vibrio cholerae (Riordan 2008) |
| IgG, IgM, IgD and IgE | These are other immunoglobulins found in breast milk in small amounts |
| Lactoferrin – an iron-binding glycoprotein | Competes with bacteria for iron, thus depriving bacteria of nutrients for proliferation Enhances iron absorption in neonate’s intestinal tract An essential growth factor for B and T lymphocytes (Riordan 2008) |
| Lysozyme – a whey protein | Acts with peroxide and ascorbate to destroy Gram-positive and other bacteria in the gut and respiratory system Increases progressively after 6 months’ lactation |
| Bifidus factor – nitrogen-containing carbohydrate | Promotes growth of anaerobic lactobacilli in the neonatal gut, providing a protective acid medium (Riordan 2008) |
| B12-binding protein | Deprives bacteria of vitamin B12 |
| Oligosaccharides – carbohydrates (monosaccharides) | Act by blocking antigens from attaching to the epithelium of the gastrointestinal tract Prevent the attachment of pneumococci (Riordan 2008) |
| Fatty acids | Disrupt membranes surrounding certain viruses and destroy them |
| Complement (C3 and C4 components) | Has the ability to fuse bacteria bound to a specific antibody and destroy them through lysis (Lawrence & Lawrence 2005) |
| Fibronectin | Facilitates the uptake of bacteria by mononuclear phagocytic cells |
| Mucins – protein and carbohydrate molecules | Adhere to bacteria and viruses (including HIV) and prevent them from attaching to mucosal surfaces (Lawrence & Lawrence 2005) |
| 2. Anti-inflammatory factors | |
| Secretory IgA, lactoferrin and lysozyme | Multipurpose anti-inflammatory role Lactoferrin inhibits the complement system and suppresses cytokine release from macrophages that have been stimulated by bacteria (Rodriguez-Palmero et al 1999) |
| Antioxidants (alpha-tocopherol, beta-carotene cystine, ascorbic acid) | Absorbed into the circulation and have systemic anti-inflammatory effects (Rodriguez-Palmero et al 1999) |
| Epithelial growth factors | Enhance maturation of the neonatal gut and limit entry of pathogens |
| Other anti-inflammatory factors include platelet-activating factor, antiproteases (alpha-antichymotrypsin and alpha-antitrypsin) and prostaglandins | |
| 3. Immunomodulators | |
| Nucleotides, cytokines and anti-idiotypic antibodies | Appear to promote development of the neonatal immune system |
| 4. Leucocytes (white blood cells) | |
| Approximately 90% of leucocytes in breast milk are neutrophils and macrophages | Eliminate bacteria and fungi by phagocytosis |
| 80% of the lymphocytes are T cells, though the cytotoxic capacity of these cells is low | |
Advantages of breastfeeding
The normal neonate
The recommendation of ‘exclusive’ breastfeeding is promoted by the DH (Kramer & Kakuma 2006, NICE 2006, Shribman & Billingham 2009) and its value to the neonate is well documented by the WHO (WHO 2007) and on the NHS website (see website) and in other publications (Britton et al 2007, Horta et al 2007, Lawrence & Lawrence 2005, NHS Centre for Reviews and Dissemination 2000, NICE 2006, Riordan 2008).
Breastfeeding has beneficial effects on the psychological and physical wellbeing of mother and baby. The action of sucking at the breast helps to initiate production of saliva that increases absorption of carbohydrate and fat. Neonatal saliva contains amylase that assists in glucose absorption and lipase that increases uptake of fatty acids (Blackburn 2007). These enzymes will be reduced if the baby is preterm and unable to suckle, as tube-feeding bypasses this process, so it is important for the midwife to assist the woman to initiate suckling as soon as the reflex is present. In addition, pancreatic secretory trypsin inhibitor is a major motogenic and protective factor in human breast milk as its presence influences gut integrity and repair (Marchbank et al 2009).
Breast milk’s immune properties have been specifically highlighted (AAP 2005, Hanson 1998a, Mannick & Udall 1996, Newman 1995, Orlando 1995). It provides protection from leukaemia (Davis 1998, Shu et al 1999); rotavirus infection (Newburg et al 1998); gastrointestinal infections (Dewey et al 1995, Golding et al 1997, Mannick & Udall 1996); respiratory tract infection (Lopez-Alarcon et al 1997, Repucci 1995); Haemophilus influenzae meningitis (Silfverdal et al 1999); urinary tract infection (Pisacane et al 1992); otitis media (Dewey et al 1995, Duncan et al 1993); and necrotizing enterocolitis (Lucas & Cole 1990). The Millenium Cohort Study estimated that a 53% reduction of re-admisssions of children to hospital with diarrhoea and lower respiratory tract infections could have been made if women exclusively breastfed for 6 months (Quigley et al 2007).
Other benefits include: improved motor/personal and social development (Michaelsen et al 2009, Wang & Su 1996); improved IQ (Florey et al 1995, Lucas et al 1992); and protection from non-insulin-dependent diabetes mellitus (Cavallo et al 1996, Chertok et al 2009, Drash et al 1994, Pettitt et al 1997); eczema, asthma, and food allergies (Coutts 1998, Hanson 1998b, Oddy 2009, Saarinen & Kajosaari 1995); and from cardiovascular disease in later life (Horta et al 2007, Leon & Ronalds 2009, Ravelli et al 2000).
Further benefits include possible protection from schizophrenia (McCreadie 1997); juvenile rheumatoid arthritis (Mason et al 1995); inflammatory bowel disease (Mikhailov & Furner 2008); Crohn’s disease and coeliac disease (Hanson 1998a, Koletzko et al 1989); development of the physiological integrity of the oral cavity, ensuring alignment of teeth and fewer problems with malocclusions (Palmer 1998); and possible protection from sudden infant death (McVea et al 2000). The action of breastfeeding has beneficial effects on dental caries, and mouth and jaw development, and reduces the risk of childhood obesity (Arenz & Von Kries 2009, Horta et al 2007, O’Tierney et al 2009).
The preterm neonate
Breastfeeding confers all of the above advantages and, because of the reduced capability of the immune system, is vital for early protection against infection. Preterm infants are particularly vulnerable to necrotizing enterocolitis, so it is very important that women are supported to breastfeed fully (Lucas & Cole 1990). Women who give birth prematurely provide perfectly balanced breast milk for their babies – the non-protein nitrogen content is 20% higher than in those who give birth at term, providing the necessary free amino acids essential for growth (Riordan 2008). Preterm breast milk contains higher concentrations of polymeric immunoglobulin A (pIgA), lactoferrin, lysozyme and epidermal growth factor. In addition, the numbers of macrophages, neutrophils and lymphocytes are higher in the colostrum (Xanthou 1998). Lingual lipases will be reduced if the baby is preterm and unable to suckle, as tube-feeding bypasses this process (see website).
The woman
Breastfeeeding confers significant health benefits on women, such as protection against several cancers, including premenopausal breast (Lee 2003) and ovarian cancer, improved bone density and reduction of anaemia. It can also be an effective postpartum contraceptive during ‘total’ breastfeeding (WHO Task Force 1999), having the added advantage of delaying menstruation and reducing anaemia (Wang & Fraser 1994). (For more information, see website.)
Contraindications to breastfeeding
There are very few absolute contraindications to breastfeeding.
Neonatal conditions (WHO/UNICEF 2009)
Maple-syrup urine disease
A special formula that is free from leucine, isoleucine and valine is required
Maternal conditions
HIV
Breastfeeding should be avoided as part of a programme of interventions to reduce the risk of mother-to-child HIV transmission (DH 2004b, RCM 1998). WHO/UNICEF advise against breastfeeding if replacement feeding is acceptable, feasible, affordable, sustainable and safe (AFASS) as is the case in the UK and developed countries (WHO/UNICEF 2009).
However, exclusive breastfeeding for the first 4–6 months continues to be advised in ‘resource-constrained’ settings, such as in sub-Saharan Africa, where HIV transmission has been found to be reduced by exclusive breastfeeding in comparison with mixed feeding (Coovadia et al 2007, Gray & Saloojee 2008, WHO/UNICEF 2009, WHO/UNICEF/UNAIDS/UNFPA 2007).
Drugs – maternal medication
Substance misuse
Substances such as nicotine, alcohol, ecstasy, amphetamines and cocaine are known to have harmful effects on the baby through breast milk. Opioids, benzodiazepines and cannabis can all cause sedation in the mother and baby. Women should be asked to abstain and cease to breastfeed while under the influence of these substances (WHO/UNICEF 2009).
Conditions where a woman can continue to breastfeed but health problems may be of concern
Hepatitis B
The baby should be given a hepatitis B vaccine within the first 48 hours or as soon as possible thereafter (WHO/UNICEF 2009). The woman can continue breastfeeding.
Pollutants in breast milk
The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment examined the high quantities of polychlorinated biphenyls (PCBs) and dioxins present in breast milk and concluded that the advantages of breastfeeding still outweighed the risks (Mitchell 1997). Intake of organochlorines measured in breast milk set against the WHO acceptable daily intakes failed to demonstrate an unacceptable intake for the baby (Quinsey et al 1996). Examination of the reported levels of the pesticide DDT in breast milk fat demonstrated a decline in most areas of the world (Smith 1999), and guidance on the implications of exposure to cadmium, lead and mercury resulted in encouragement of breastfeeding under ‘most circumstances’ (Abadin et al 1997).
The role of the midwife
Knowledge of breastfeeding
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