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Artificial feeding 

Artificial feeding
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Artificial feeding
DOI:
10.1093/med/9780199584673.003.0025
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  • Introduction [link]

  • Suppression of lactation [link]

  • Selecting an appropriate substitute [link]

  • Types of formula milks [link]

  • Alternatives to modified cow's milk formulas [link]

  • Nutritional requirements of formula-fed babies [link]

  • Management of artificial feeding [link]

  • Problems associated with formula feeding [link]

  • Disadvantages associated with formula feeding [link]

  • Health risks associated with formula feeding [link]

Introduction

Although breastfeeding is best for mother and infant there will always be some mothers who choose to artificially feed their infants. This is usually for social, psychological, or cultural reasons, but there will be some cases where breastfeeding is contraindicated for medical reasons (Artificial feeding see Contraindications to breastfeeding, [link]). There will also be mothers who commence breastfeeding but, for a variety of reasons, discontinue earlier than they intended.

All pregnant women should be told of the benefits of breastfeeding but ultimately it is the mother's choice which feeding method she adopts. If the mother decides to bottle feed, give her guidance to ensure that she does so safely, but do not give her the impression that formula milk is equivalent to breastfeeding, or that it is without risk.1

Suppression of lactation

If a mother does not wish to breastfeed her infant, has a late miscarriage or a stillbirth, lactation will still occur and she may experience discomfort for several days.

Aetiology

  • The classical theory is that milk secretion is controlled principally by the maternal hormones prolactin and oxytocin.

  • However, removal of milk from the breasts has also been found to be a crucial element in milk secretion.

  • If milk is not removed from the breast, a chemical (autocrine inhibitor) in the whey protein fraction prevents further production by exerting a negative feedback control. This is known as the feedback inhibitor of lactation.

  • A build-up of this autocrine inhibitor then accelerates the breakdown of milk components already produced.

Management

  • If unstimulated, the breasts will naturally stop producing milk.

  • The breasts should be well supported, but binding has not been shown to contribute towards suppression of lactation.

  • If there is severe discomfort with engorgement, encourage the mother to express very small amounts of milk once or twice. This can help relieve the discomfort without interfering with the regression of lactation.

  • Give mild analgesics to assist in relieving the pain and discomfort felt.

  • Do not restrict fluids.

  • Pharmacological suppression using dopamine receptor agonists is effective, but is not advised for routine use.1

International code of marketing of breast milk substitutes

In May 1981, the World Health Assembly approved an International Code of Marketing of Breast Milk Substitutes.2 The purpose of this code was to protect the practice of breastfeeding and to help control the marketing of products for the artificial feeding of infants. Nowhere does it seek to enforce breastfeeding, and the code does not prevent mothers from bottle feeding if that is what they choose to do. At present the code is voluntary in the UK, but some countries have chosen to enshrine it in law. Employees in Baby Friendly Hospitals and community healthcare facilities are required to ensure that their practice is in line with the International Code and not just with the UK law.3 The code has major implications for the work of the midwife. The major recommendations are included in Box 25.1.

Selecting an appropriate substitute

All artificial milks are highly processed, factory-produced products. Under UK law it is an offence to sell any infant formula as being suitable from birth unless it conforms to the compositional and other criteria set out in the Infant Formula and Follow-on Formula Regulations 1995.

  • Health professionals must not recommend one brand of formula over another.

  • There is no scientific basis for recommending one brand over another.

  • There is no reason for a mother to remain with one brand.

  • All common baby milks suitable for home use are supplied in dried powder form so they can be stored and transported without risk of deterioration.

  • Many manufacturers also supply individual feed sachets and ready-to-feed cartons. These are handy to use but tend to be more expensive.

  • The DH recommends that soya formula should only be used for babies who are intolerant of cow's milk or lactose, and only with medical guidance.

  • For babies and infants who are intolerant of standard formulas, alternative formulas, such as hydrolysate and amino-acid-based formulas, are medically prescribed.

Types of formula milks

Whey and casein are proteins found in milk. Formulas are modified to vary the ratio of these proteins. There are two main types, whey-dominant and casein-dominant formulas.

Whey-dominant formulas

  • Whey is the dominant protein in human milk.

  • Whey-based formulas have been modified so that the whey:casein ratio (60:40) is closer to that of human milk.

  • These formulas are more easily digested, which affects gastric emptying times and leads to feeding patterns similar to those of breastfed babies.

  • These formulas are suitable for use from birth to 1 year.

Casein-dominant formulas

  • Casein is the dominant protein in cow's milk.

  • Casein-dominant formulas have been modified so that the whey:casein ratio is 20:80 and is nearer to the type found in cow's milk.

  • These formulas are not comparable to breast milk.

  • Such feeds form large, relatively indigestible curds in the stomach, which are intended to make the infant feel full for longer. However, there is little evidence to support this.1

  • They are advertised for the hungrier bottle-fed baby and can be used from birth to 1 year.

  • There may be an even greater metabolic demand on the infant when these formulas are given.2

  • Babies who are settled and gaining weight on whey-dominant formulas will not need casein-dominant formulas.

Additional ingredients

Whey- and casein-dominant formulas may also have additional ingredients, for example long-chain fatty acids (LCPs), nucleotides, B-carotene, and selenium. The ingredients and their sources vary from one brand to another.

LCPs

  • Occur naturally in breast milk.

  • Aid brain, eye, and, CNS development.

  • Are added to formulas in the form of fish oils or egg yolk.

Research into both the long- and short-term effects of adding LCPs to formulas is continuing.

ß-carotene

  • Occurs naturally in breast milk.

  • Can be metabolized by the baby to produce vitamin A.

Nucleotides

  • Nucleotides are present in breast milk.

  • Assist with development of the baby's immune system.

  • Aid adsorption of other nutrients from breast milk.

Selenium

  • An antioxidant found in breast milk.

Specially modified formula

Several formula manufactures have recently introduced specially modified formulas which they claim aids digestion and helps reduce some of the common problems associated with formula feeding, e.g. constipation, colic. These products are available over the counter but their efficacy needs further research.

Follow-on milks

These milks are made from slightly modified cow's milk and they have added vitamin D and iron.

  • They are not to be given to infants <6 months old.3 , 4

  • The large amounts of iron may make some babies constipated.

  • Full-fat cow's milk has low levels of iron and vitamin D and should not be used as a main drink for an infant under 1 year of age. However, it can be used for preparing baby weaning foods from 4–6 months of age.

  • If an infant tolerates a well-balanced and varied diet, full-fat cow's milk can be used from the age of 1 year.

Good night milks

  • ‘Good night milks’ have added starch and rice flakes, and are represented as helping to settle babies at bedtime and are promoted for use as a bedtime liquid feed from a bottle or feeding cup.

  • The Scientific Advisory Committee on Nutrition5 has identified no scientific evidence that demonstrates ‘good night’ milk products offer any advantage over the use of currently available infant formulas.

  • Concern expressed that their promotion will encourage parents to believe that it is desirable for a baby to sleep longer at an age when healthy infants show considerable variation in normal sleeping patterns.

  • There is a potential risk that mothers may consider the product suitable for ‘settling’ their infant more than once a day and use these products on occasions additional to bedtime.

  • An even greater concern is that they may be used to ‘settle’ infants <6 months. Such unintended use would be contrary to advice that gluten-containing products should not be given to infants <6 months of age.5

Thickened formulas

  • Pre-thickened formulas are advertised for infants with reflux or possetting.

  • They are casein-based infant formulas with added pre-gelatinized starch. They thicken when in contact with the acid in the stomach and this increases the feed thickness while still flowing easily through the teat.

  • Infants taking these formulas should not be prescribed thickeners or anti reflux medication such as Gaviscon®.

  • Can be purchased over the counter or they may be prescribed.

  • Most infants do not need this sort of preparation once solids have been established as part of their diet. However, they are suitable for use up to the age of 1 year.

  • Extra care is needed when making up some of these feeds as they require cooled boiled water. Water at 70° will cause the feed to thicken in the bottle.

Alternatives to modified cow's milk formulas

Specialized formula milks are available for parents who wish their baby to have vegetarian feeds. These should only be given under the direction of a dietitian.

Soya formula

  • It is recommended by the DH that these milks should only be used if a baby/infant is intolerant to cow's milk or lactose; and, generally, only under medical guidance.

  • There are concerns about the possible effects of oestrogen-like compounds produced by soyabeans (phyto-oestrogens), and unacceptable levels of manganese and aluminium, in such formulas.1

  • They may contain genetically modified ingredients.

Specialist formulas for babies intolerant to standard formulas

Predicting allergies is an inexact science. The likelihood has been estimated2 to be:

  • 30–35% if one parent is affected

  • 40–60% if both parents are affected

  • 50–70% if both parents suffer the same allergy.

Lactose-free formulas

  • Appropriate for infants who are intolerant to lactose but can tolerate the milk protein.

  • Cow's milk protein based with lactose replaced by glucose.

  • Prescribable or may be purchased in pharmacies.

  • Glucose in these formulas may be dangerous to teeth.

Hydrolysate formulas

  • Used if breastfeeding is not possible.

  • Prescription only.

  • Some are designed to treat an existing allergy; some are designed to prevent an allergy.

  • Prescribing guidelines: some hydrolysate formulas need proven intolerance, whereas others do not.

Amino-acid-based formulas

  • Have a completely synthetic protein base.

  • Are very expensive.

Nutritional requirements of formula-fed babies

Three areas need to be taken into consideration:

  • Energy requirements

  • Fluid requirements

  • Balance of ingredients.

Energy requirements

  • The average healthy baby will thrive on 440kJ/kg of bodyweight per day.

  • Breast milk and formula milk contain approximately 90kJ/30mL.

  • A 3.5kg baby would therefore require 1540kJ in 24h = approximately 525mL of milk.

This is only a guide, and individual babies will take as much as they require at each feed to satisfy their needs. This amount may vary from feed to feed and the overall picture should be considered, e.g. the general health and weight gain of the baby.

Fluid requirements

  • An average healthy baby requires 150–165mL of fluid per kg of bodyweight per day to remain hydrated.

  • A 3.5kg baby would therefore require approximately 525–575mL per day.

Balance of ingredients

Formula feeds are developed from cow's milk, which is balanced to meet the needs of calves and therefore requires modification for human infants. ‘Modified milks’ are those that have had the balance of ingredients adjusted to resemble human milk as closely as possible.

Modifications include:

  • Most of the casein is removed and replaced by whey protein

  • Some of the milk fat is removed and replaced by vegetable fat

  • Lactose is added to increase the energy value

  • Vitamins are added to resemble levels in human milk

  • Minerals are adjusted to resemble levels in human milk

  • Higher levels of iron are required as it is less bio-absorbable from formulas than from breast milk.

Management of artificial feeding

Sterilization of infant feeding equipment

All infant feeding equipment must be completely clean and sterilized prior to use. This includes any equipment used for breastfed babies or for storing EBM, e.g. bottles, teats, breast pumps, and nipple shields. This is to protect babies against any potential sources of infection. Due to their immature immune system, babies are at risk of infection, particularly gastroenteritis (potentially life-threatening for newborn babies) and fungal infections (which can be difficult to treat).

Demonstrations of sterilization of equipment are best given on a one-to-one basis in the mother's home environment.

Types of sterilization

  • Boiling

  • Chemical sterilization

  • Steam sterilization

  • Microwave sterilization using a microwave sterilization unit. This is not suitable for metal items or certain types of plastic.

For all types of sterilization

Before sterilization

  • Wash all bottles and other equipment thoroughly in hot, soapy water, using a bottle brush. Scrub both inside and outside to remove fatty deposits. Pay special attention to the rim.

  • Clean the teat by either:

  • Using a small teat brush

  • Turning inside out and washing in hot, soapy water.

  • Rinse all the washed equipment thoroughly with non-soapy water before sterilizing.

After sterilization

Always wash your hands before removing equipment from the sterilizer.

To sterilize by boiling

  • Put the equipment in a large pan filled with water, ensuring that there is no air trapped in the bottles or teats. Cover the pan with a lid and bring to the boil.

  • Boil for 10min, ensuring that the pan does not boil dry.

  • Allow the water to cool and store the equipment in the covered pan until required. Use the equipment within 12h (if longer, repeat the process).

  • Remove equipment from the saucepan carefully, to avoid desterilization.

  • Check bottles and teats regularly for any signs of deterioration. If this is detected, discard them. Prolonged boiling of teats may destroy them.

To sterilize using chemicals (cold water sterilization)

  • Use the liquid or tablets to make up the solution following the manufacturer's instructions.

  • Either use a sterilizing tank or a large container with a well-fitting lid.

  • Submerge the equipment, ensuring that no air bubbles are trapped in the bottles or teats.

  • Keep all the equipment under the water, using the plunger provided or a plate.

  • Leave in the solution for a minimum of 30min.

  • Discard the solution and make up fresh every 24h.

  • Use cooled, boiled water if you wish to rinse the equipment prior to use.

Sterilization using a steam or microwave sterilizer

  • Follow the manufacturer's instructions.

  • Sterilizing in a microwave without a microwave sterilizer is not advisable.

Preparing a formula feed

The correct preparation of infant formula feeds is important to prevent such conditions as dehydration, constipation, and gastroenteritis. The Food Standards Agency and the DH1 have produced new guidelines on the safe preparation of infant formulas to reduce the risk of gastroenteritis. Powdered infant formula is not a sterile product and may contain bacterial contaminants. Enterobacter sakazakii and Salmonella are those of greatest concern. Both NICE and UNICEF UK recommend that all mothers who are artificially feeding their infants should be shown the correct method of preparing a formula feed prior to discharge from hospital.2 , 3

Methods of making up formula feeds

  • Scoop method

  • Individual feed sachets

  • Ready-to-feed cartons.

Scoop method

  • A fresh bottle should be made up for each feed. This is because bacteria multiply quickly at room temperature and may survive and multiply slowly in some fridges, therefore storing formula milk can increase the risk of gastroenteritis.

  • The feed should be made up with water of around 70°C as this will destroy most bacterial contaminants. This means boiling the kettle and leaving it to cool for no longer than 30min. Do not use bottled or artificially softened water.

  • Read the tin or pack to find out how much water and formula you require.

  • Clean a surface on which to prepare the feed. Wash your hands thoroughly with soap and water, and dry on a clean towel.

  • All equipment used for making up the feed must have been freshly sterilized.

  • If using a sterilizer, remove the lid, turn upside down and place the teat(s) and cap(s) in it. If using a chemical (cold water) sterilizer rinse with cool, boiled water (not tap water) if wished.

  • Remove the bottle rinse with cooled, boiled water (if wished) and stand on a clean, flat surface. Pour cool boiled water which should still be hot into the bottle, up to the required mark. This is better if undertaken at eye-level.

  • Measure the exact amount of formula using the scoop provided. Level the formula in the scoop using the knife or spatula provided.

  • Do not compress or compact the formula in the scoop.

  • Add the formula to the water in the bottle never the other way round. In the UK all baby formulas use one scoop to 1oz (30mL) of water.

  • Do not add anything else to the feed unless medically prescribed.

  • Apply the top or teat and cover. Shake the bottle well until all the formula is dissolved.

  • Cool the feed down to required temperature by holding the bottle with the cap in place, under cold running water.

  • Check the temperature of the formula prior to feeding the baby, by dripping a little on to the inside of your wrist; it should be lukewarm but not hot.

  • Discard any formula that has not been used within 2h, clean and re-sterilize the bottle.

When it is not practical to make up feeds just before feeding

It is best to make up feeds individually as required but this may not always be practical. Ready to use formula is the safest option but this is more expensive.

Feeding the baby away from home

It is safest to carry a measured amount of formula powder in a small, clean, dry container, a flask of hot water that has been boiled and an empty sterilized feeding bottle. The feed is then made up fresh as required. The water should still be hot when used and therefore the bottle will need to be cooled before giving to the baby.

Making-up and transporting feeds for later use

If the above advice is difficult to follow, e.g. if preparing and transporting feeds either to a nursery or child minder the following steps should be adopted.

  • Prepare feeds individually, not in one large container.

  • Make the feeds up the day they are required not the night before. This reduces storage time therefore reduces the risk.

  • Once prepared store at the back of a fridge at below 5°C.

  • Ensure the feed has been in the fridge for at least 1h before transporting.

  • Store for the minimum of time.

  • Remove from the fridge just before leaving home and transport in a cool bag with ice packs.

  • Use within 4h. If arriving at the destination in <4h, remove from the cool bag and store in the back of a fridge below 5°C.

  • Never store reconstituted feeds for more than 24h.

  • Re-warm before use.

Re-warming stored feeds

  • Only remove the feed from the fridge just before it is needed.

  • Re-warm using a bottle-warmer, or placing in a container of warm water.

  • Never use a microwave to re-warm a feed.

  • Never warm for more than 15min.

  • Shake the bottle to ensure even heating of the feed.

  • Check the temperature before feeding the baby.

Principles of artificial feeding

  • Feed the baby when he or she is hungry.

  • Let him or her take as little or as much as desired.

  • Ideally, the minimum of caregivers should feed the baby and he or she should not be passed from person to person for feeding.

  • Never feed babies by ‘bottle propping’ and never leave them unattended when feeding from a bottle.

  • Make up feeds individually as required.

  • Test the temperature of the feed on the inside of your wrist before offering it to the baby.

  • Feeding times should be enjoyable and relaxed.

  • Hold the baby securely, and close to your body, in a similar position to that used in breastfeeding.

  • Maintain eye contact.

  • Ensure that the teat covers the baby's tongue, and tip the bottle up sufficiently so that air is excluded from the teat.

  • The baby will suck and pause while retaining the teat in their mouth.

  • During the feed, when necessary, sit the baby in an upright position so he or she can bring up wind; this may be once or twice.

  • It is normal for babies to regurgitate small amounts (posseting).

  • If the baby is sucking but the feed does not appear to be reducing, check the teat for blockages.

  • The baby will stop feeding when he or she has had enough.

  • If the baby is draining the full amount offered, the amount should be increased.

  • Any feed left at the end of the feed should be discarded and should never be reheated.

Problems associated with formula feeding

Constipation

It is the consistency, not the frequency, of bowel movements that should be considered when discussing constipation. Babies may go several days without a bowel movement, but if the stools are soft and yellow, then no treatment is required. Constipation results from reabsorption of water from the stools and stools present as hard, round pellets.

Management

  • Check that the condition is constipation and not just infrequent stools.

  • Ensure that the feeds are being prepared correctly, i.e. the water is being placed in the bottle prior to the formula, the powder in the scoop is not being compressed, and extra scoopfuls are not being added.

  • Offer the baby cooled, boiled water between feeds. There should be no additives to the water, e.g. brown sugar or orange juice.

  • Try an alternative make of formula; not all formulas suit all babies.

  • If the above strategies do not work, seek a medical opinion.

Posseting

It is normal for a baby to regurgitate a small amount of milk following a feed. Reassure the mother that it is normal and take no action unless it becomes persistent or projectile vomiting, in which case medical aid should be sought immediately.

Disadvantages associated with formula feeding

The following disadvantages for the formula-fed infant have been identified.1

Formula milk is deficient in:

  • Some nutrient compounds (e.g. epidermal growth factors)

  • Cells (e.g. leucocytes, macrophages) which are important in protecting the infant from a wide variety of pathogens

  • Antibodies, antibacterial, and antiviral factors (e.g. lgA, IgG, IgM, lactoferrin)

  • Hormones (e.g. prolactin, thyroid hormones)

  • Enzymes (e.g. mammary amylase, milk lipase, lysozyme)

  • Prostaglandins.

These deficiencies are important to the infant's immunological and hormonal responses, as well as neonatal development and cell maturation.

The formula-fed infant may be further compromised by:

  • The presence of cow's milk or soya proteins

  • Possibility of errors during manufacture, including incorrect manufacture, bacterial contamination, foreign bodies, etc.2

  • Addition of new ingredients on an uncertain scientific basis

  • Frequent errors in the preparation of feeds, which alter their concentration3

  • Variability of the mineral and trace element content in the water used to reconstitute feeds.

Formulas may be contaminated with bacteria and/or pathogens:

  • During manufacture

  • While preparing feeds at home with unclean utensils and/or contaminated water.

Examples of specific types of formulas

This is not a comprehensive list of all Infant formulas. There may be other specific types of formulas that have not been included as brand names change frequently due to constant research and re-branding by formula companies.

Examples of whey- and casein-dominant formulas (Table 25.1)

Table 25.1 Examples of whey- and casein-dominant formulas

Whey-dominant formula

Casein-dominant formula

(60% whey, 40% casein)

(80% casein, 20% whey)

Aptamil First®

Aptamil Extra Hungry®

Cow and Gate First Milk®

Cow and Gate for Hungrier Babies®

Heinz Nurture Newborn®

Heinz Nurture Hungry baby®

SMA First Infant Milk: Stage 1®

SMA Extra Hungry®

HIPP Organic First Infant Milk®

HIPP Organic Second Infant Milk®

Examples of soya infant formulas

  • Heinz Nurture Soya®

  • Infasoy (Cow & Gate)®

  • Isomil (Abbott)®

  • Prosobee (Mead Johnson)®

  • Wysoy (SMA)®

Examples of specially modified formulas

  • Aptamil Easy Digest®

  • Cow and Gate Comfort First®

  • Heinz Nurture Gentle®

Examples of follow-on milks

  • Aptimil Follow-on®

  • Cow & Gate Complete Care Follow-on®

  • Cow & Gate Comfort Follow-on®

  • Heinz Nurture Growing Baby Follow On®

  • Heinz Nurture Gentle Follow-on®

  • HIPP Organic Follow-on Milk®

  • SMA Follow-on Milk: Stage 2®

Examples of pre-thickened formulas

  • Enfamil AR (Mead Johnson)®

  • SMA Stay Down®

Examples of ‘good night milks’

  • Cow & Gate Good Night Milk®

  • HIPP Organic Good Night Milk®

Health risks associated with formula feeding

The RCM1 stated that, taking breastfeeding as the ‘gold standard’, bottle-feeding has been shown to be associated with certain health risks.

For the infant:

  • Increased risk of gastrointestinal infections

  • Increased risk of respiratory infections

  • Increased incidence of otitis media

  • Increased risk of urinary infections

  • Increased risk of atopic disease in families where there is a history of this disease

  • Increased risk of sudden infant death

  • Increased risk of insulin-dependent diabetes mellitus

  • Reduced cognitive development

  • Decreased visual acuity

  • Reduced intelligence quotient (IQ) in preterm infants

  • Increased risk of NEC.

Some risks that manifest in later life have been demonstrated, including:

  • Cardiovascular disease

  • Obesity

  • Some childhood cancers.

For the mother:

  • Increased risk of ovarian and premenopausal breast cancer. The exact mechanisms whereby breastfeeding affords protection against these cancers are not fully understood. However, in the case of breast cancer it is thought to be linked with increased circulating hormones, which result in systemic metabolic effects as well as structural changes in the breast; whereas in the case of ovarian cancer it is believed that breastfeeding may afford a protective effect as a result of inhibition of ovulation.2

  • Increased risk of hip fractures and reduced bone density. Prolactin, which is released during breastfeeding, increases the rate at which vitamin D is converted to its active form, and this enhances calcium utilization.3

For full reference sources and details of further associated risks see Appendix 5 in RCM (2002)1 and the UNICEF UK Baby Friendly website (Artificial feeding www.babyfriendly.org.uk).

Notes:

1 Royal College of Midwives (2002). Successful Breastfeeding. Edinburgh: Churchill Livingstone.

1 Inch S (2009). Infant Feeding. In: Fraser DM, Cooper MA (eds). Myles: Textbook for Midwives. Chapter 41. Edinburgh: Churchill Livingstone.

2 World Health Organization (1981). International Code of Marketing Breast Milk Substitutes. Geneva: WHO

3 UNICEF UK Baby Friendly Initiative (2008). Three-day Course in Breastfeeding Management: Participant's Handbook. London: UNICEF.

1 White A, Freeth S, O'Brien M (1992). Infant Feeding 2000. London: HMSO.

2 Inch S (2009). Feeding. In: Fraser DM, Cooper MA (eds) Myles Textbook for Midwives. Chapter 41. Edinburgh: Churchill Livingstone, 1990.

5 Scientific Advisory Committee on Nutrition (2008). Consideration of the Place of Good Night Milks Products in the Diet of Infants Aged 6 Months and Above. London: SACN. Available at: Artificial feeding www.sacn.gov.uk/reports_position_statements/position_statements/index.html (accessed November 2009).

1 Minchin M (1998). Breastfeeding Matters, 4th edn. Australia: Alma Publications.

2 Brostoff J, Gamlin L (1998). The Complete Guide to Allergy and Food Intolerance. London: Bloomsbury Publishing.

1 Food Standards Agency/Department of Health (2007). Guidance for Health Professionals on Safe Preparation, Storage and Handling of Powered Infant Formula. London; FSA.

1 Henschel D, Inch S (1996). Breastfeeding: A Guide For Midwives. Cheshire: Books for Midwives Press, p. 20.

2 Minchin M (1998). Breastfeeding Matters, 4th edn. Australia: Alma Publications.

3 Lucas A, Lockton S, Davies PS (1992). Randomized trial of ready-to-feed compared with powered formula. Archives of Diseases in Childhood 67, 935–9.

1 Royal College of Midwives (2002). Successful Breastfeeding. Edinburgh: Churchill Livingstone.

2 Heinig MJ, Dewey KG (1997). Health effects of breastfeeding for mothers: a critical review. Nutrition Research Reviews 10, 35–56.

3 Palmer G (1988). The Politics of Breastfeeding. London: Pandora Press.