[Editor's Note: A big hello to Science and Sensibility readers! As this is my first post, I would like to take a minute to thank Deena for the wonderful job she did on Science and Sensibility in February. I look forward to spending the month of March with you. Enjoy! - Lisa Baker]

As discussed in last week's post, the American Academy of Pediatrics (AAP) revised policy statement on Breastfeeding and the Use of Human Milk reaffirms the recommendation of exclusive breastfeeding for six months and a continuation of breastfeeding for 1 year or longer (1). It has been well established that the act of breastfeeding and the consumption of human milk has numerous benefits to infant, mother, and society. As outlined in the policy statement, the benefits of human milk consumption for the preterm infant are significant and include:

• lower rates of necrotizing enterocolitis (NEC) and sepsis
• fewer readmissions to hospital
• higher intelligence testing scores and higher total brain volume
• lower rates of retinopathy of prematurity
• lower blood pressure and low-density lipoprotein concentrations
• improved leptin and insulin metabolism

The benefits of human milk to the preterm infant are so significant that the AAP recommends, 'If mother's own milk is unavailable despite significant lactation support, pasteurized donor milk should be used'(1). This week's posts will further explore the topic of donor human milk for the premature infant.

Donor human breast milk vs cow's milk-based formula

When a mother's breast milk is not available, preterm infants can be given either donor breast milk or commercially made formula. Feeding preterm infants pasteurized donor milk over formula is the recommendation expressed by a long list of organizations. Such groups include the AAP, Canadian Pediatric Society, United States Breastfeeding Committee, Breastfeeding Committee for Canada, and La Leche League International (1-5). Evidence to support this recommendation largely comes from a 2007 systematic review by Quigley et al. (6) and a 2010 trial by Sullivan et al. (7). In both cases the rates of NEC were significantly higher in preterm infants fed cow's milk-based formula products versus those fed only human milk.

The review performed by Quigley et al. compared formula feeding to donor breast milk in eight separate studies, involving a total of 1,017 infants. The authors concluded, 'feeding with formula milk, compared with donor breast milk, leads to higher rates of short-term growth in preterm or low birth weight infants, but is associated with an increased risk of developing necrotizing enterocolitis' (6). The results of short-term growth should be taken with caution, however, as only one of the eight trials included nutrient-fortified breast milk (a common practice in today's NICU). Fortifying human milk has been shown to increase short-term growth rates, but does not appear to affect growth beyond infancy (8).

The study by Sullivan et al. included 207 extremely premature infants and showed a 77% reduction in the odds of developing NEC (odds ratio of 0.23 (95% CI=0.08,0.66), P=. 007) in infants that consumed only human milk and human milk-based fortifiers compared to infants that consumed cow's milk-based products (7).

Pasteurization of donor breast milk
In accordance with recommendations from the AAP and Canadian Pediatric Society (CPS), as well as the remaining aforementioned organizations, donor human milk offered to premature infants must be pasteurized (1-5). As a human body substance, breast milk must be properly collected and stored, subject to screening and testing, pasteurized, and cultured. Pasteurization involves heating breast milk to inactivate bacterial and viral contaminants. The heating process can also alter the breast milk itself. The CPS policy statement on milk banking provides a summary of the alterations caused by a common form of pasteurization in milk banks (heating milk to 62.5oC for 30 minutes; the Holder method):

• Carbohydrates, fats and salts are unchanged.
• Thirteen per cent of the protein content is denatured.
• Fat-soluble vitamins are unchanged.
• While not all of the water-soluble vitamins have been studied, some have been shown to degrade following pasteurization.
• All beneficial immune cells are also inactivated.
• Secretory immunoglobulin IgA, which binds microbes within the digestive tract, is found at 67% to 100% of its original activity.
• Targeted IgG antibodies are reduced at 66% to 70%.
• IgM antibodies are completely removed.
• Lactoferrin, which binds iron required by many bacteria, thus reducing their growth, is reduced to 20% of its original level.
• Lysozyme enzyme, which attacks bacterial cell walls, drops to 75% activity.

Despite these alterations, pasteurized breast milk still contains far more beneficial elements than formula and is the preferential alternative to mother's own fresh breast milk.

Supply of pasteurized donor breast milk in Canada

To meet the recommendation of properly pasteurized milk, Canadian hospitals receive their donor milk from one of the milk banks associated with the Human Milk Bank Association of North America (HMBANA). The HMBANA is a non-profit association of donor human milk banks established to set standards for and facilitate establishment and operation of milk banks in North America. These banks have rigorous screening methods for all donors and stringent protocols for pasteurization and handling of breast milk. The milk is sold to hospital NICU's on a cost-recovery basis. As of 2011 there were 11 accredited HMBANA milk banks in North America. Only one of those banks is located in Canada (British Columbia). HMBANA banks are being developed in Ontario and Alberta and the Calgary Mothers' Milk Bank (Alberta) is already accepting milk donations. Despite this recent development, Canadian hospitals are still critically short on donated breast milk. Milk that is available is reserved for the most critical preterm infants or newborns that require gastrointestinal surgery (2). There is certainly room for more banks to supply the large demand of breast milk to preterm and critically ill newborns.

In light of the need for more banks in North America, HMBANA has established guidelines and best practices for those wishing to start and operate a functional milk bank. In our next post series we will interview Jannette Festival, Founder and Executive Director for the newly established Calgary Mothers' Milk Bank, to discuss the process of creating a milk bank and the potential future of milk banks in Canada and North America.

References

1. American Academy of Pediatrics. Policy Statement: Breastfeeding and the Use of Human Milk. Pediatrics 2012; 129: e827-e841. Available at http://pediatrics.aappublications.org/content/early/2012/02/22/peds.2011-3552
2. Canadian Paediatric Society. Position Statement: Human Milk Banking. Paediatrics and Child Health 2010; 15 (9):595-8. Available at http://www.cps.ca/english/statements/N/N10-01.htm.
3. United States Breastfeeding Committee. Statement on the Safe Use of Donor Human Milk. Washington, DC: United States Breastfeeding Committee. 2008. Available at http://www.usbreastfeeding.org/LinkClick.aspx?link=Position-Statements%2fDonor-Milk-Statement-2008-06-18-USBC.pdf&tabid=227&mid=587.
4. The Breastfeeding Committee of Canada. Breastfeeding Statement of The Breastfeeding Committee of Canada. 2002. Available at http://www.breastfeedingcanada.ca/Publications.aspx.
5. La Leche League International. Policy regarding the donation of human milk. 2011. Available at http://www.llli.org/release/milksharing.html.
6. Quigley MA, Henderson G, Anthony MY, McGuire W. Formula milk versus donor breast milk for feeding preterm or low birth weight infants (review). Cochrane Database of Systematic Reviews 2007; 1-41. Available at http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002971.pub2/abstract
7. Sullivan S et al. An Exclusively Human Milk-Based Diet Is Associated with a Lower Rate of Necrotizing Enterocolitis than a Diet of Human Milk and Bovine Milk-Based Products The Journal of Pediatrics 2010; 156:562-7.
8. Kuschel CA, Harding JE. Multicomponent fortified human milk for promoting growth in preterm infants. Cochrane Database of Systematic Reviews 2004, Issue 1. Available at http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD000343.pub2/abstract.

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