Some Facts About Donor Milk

Donor milk:

Increasing numbers of studies are suggesting that human milk is superior to formula for infants in terms of preventing infections and reducing rates of asthma and allergies. Many women are choosing to give their babies human milk from a donor mother or a milk bank, as opposed to formula, for reasons related to health, inability to breastfeed, very low milk production or personal choice. As donor milk has become increasingly popular, more milk banks are opening in response to the demand. Donor milk is now widely available outside of the NICU and mothers of term infants can choose to give their child human donor milk instead of formula.

Is Donor MIlk Tested or Screened?

Milk donors themselves are screened (via blood tests) for HIV-1, HIV-2, human T-cell leukemia virus 1 and 2, hepatitis B, hepatitis C, and syphilis. They are also asked if they use recreational drugs. Some exclusions and temporary disqualifications include certain medications, chronic diseases, and risk behaviors for communicable diseases. The milk itself is not tested.

Milk banking activity varies greatly between different parts of the world for a variety of reasons, some having to do with economics or funding and some due to religious and cultural factors.

The standard practice is that donor milk is typically pooled and pasteurized. Pasteurization is carried out in a water bath at 62.5°C for 30 min followed by rapid cooling. Milk bottles are then stored at –20°C until use of the milk. This method (Holder pasteurization) is widely felt to represent a good compromise between microbiological safety and nutritional/biological quality of donor milk. It is important that the cooling chain is never interrupted; therefore, special cooling bags or cooling boxes have to be used during transportation from home to the milk bank.

Breast milk contains live cells and the act of pasteurization has led to concerns that some or all of the protective effects of human milk may be lost. Studies assessing milk components before and after pasteurization have documented that several important components of human milk are reduced in concentration or are eliminated altogether, as summarized in the table below.

Breast Milk Components:

Component Retention % after Pasteurization (1)
C3 0%
IgA 0-150%
IgG 0-82.8%
IgM 0%
Lactoferrin 0-123%
Lysozyme 0-393%
Leukocytes 0% functionality
Lymphocytes 0% functionality
Alpha-1 antitrypsin 61.80%
Lipoprotein lipase destroyed
BIle Salts destroyed
Whey to casein protein ratio: Destroyed relative to fat
Vitamin A 103%
VItamin B1 65-85%
Vitamin B2 77-94%
VItamin B6 85-93%
Vitamin C 64-94%
VItamin D 103%
VItamin E 106%
Zinc Different pattern seen

Heat treatment affects anti-infective and cellular components, growth factors, and some nutrients, depending on the heat and duration of exposure. Enzymes are most heat sensitive while immune components are compromised but not completely destroyed.

Processing of human milk also affects unsaturated fatty acids and damages the membrane of milk fat globules. Human milk contains stem cells and it is thought they may be damaged during heat treatment. On the other hand, some important protective components such as the oligosaccharides are essentially resistant to the effects of heat.

Given these effects of high-temperature processing, it would be expected that the protective effects of human milk might be diminished but not abolished altogether. That is exactly what the literature shows. In 5 trials comparing formula with donor milk with regard to the incidence of necrotizing enterocolitis, the risk of necrotizing enterocolitis was not significantly diminished in each trial. All five 5  showed a significant protective effect of donor milk compared to formula (2).

A direct comparison of fresh against pasteurized human milk performed by Narayanan et al., and showed a somewhat reduced protective effect against infection (14.3 vs. 10.5% infection) which was still much stronger than the effect of formula (33.3% infection). It is pretty clear that the beneficial effects of pasteurized human milk are diminished when compared to freshly expressed milk but that enough of the protective effects remain to render donor milk the feeding of choice for premature infants in the absence of any or sufficient maternal breast milk (3).

Donating Milk:

Milk donation is an act of unselfishness. In most countries donors receive no compensation, but some donors receive modest monetary compensation for actual costs incurred.

Human Milk Banks in the U.S.:

At the time of writing this post there are currently 26 milk backs in the US.

How is donor milk screened?

The milk itself is not tested. Milk banks will culture the milk and the processing equipment at various times determined by their own schedule.

Bottom Line:

  • It is ideal to have own mother’s milk

  • Another mother’s milk or donor pooled pasteurized milk is another increasingly more popular choice.

  • Formula when needed or chosen by mom.


  1. Arnold LDW: Human Milk in the NICU: Policy into Practice. Ontario, Jones and Bartlett Publishers, 2010.

  2. Chauhan M, Henderson G, McGuire W: Enteral feeding for very low birth weight infants: reducing the risk of necrotising enterocolitis. Arch Dis Child Fetal Neonatal Ed 2008;93:F162-F166.

  3. Narayanan I, et al: A planned prospective evaluation of the anti-infective property of varying quantities of expressed human milk. Acta Paediatr Scand 1982;71:441-445.