Resource for the Informed Sharing of Human Milk

When a baby is born prematurely or very prematurely, there are specific issues that need to be addressed regarding nutrition and protection from infections.

At first, premature babies can have difficulty tolerating any food that is introduced to their delicate system. The adaptation to normal feeding can pose problems for various reasons and until proper digestion is established, these babies receive nutrients via an intravenous line.

One’s own milk
When a baby is able to digest human milk, the best food for a premature baby is raw, unpasteurized milk from their own parent. There is strong and consistent evidence that feeding one’s own milk to preterm infants of any gestation is associated with a lower incidence of infections and necrotizing enterocolitis, as well as improved neurodevelopmental outcomes as compared with formula feeding.¹ ²

The benefits of human milk and its anti-infective components have been well established and are especially important for the protection of preterm infants. Please see Why breastmilk? for more information on the antimicrobial properties of breastmilk.

Every effort needs to be made by the hospital staff to encourage and support the parent of a preterm baby to express her own milk. Separation, stress, fatigue, and the possible precarious condition of the infant can affect milk production. Counseling parents of preterm infants has been shown to increase the incidence of breastmilk feeding.³ When parents are involved in the care and feeding of LBW infants, substantial benefits in terms of improved breastfeeding rates and early discharge from the hospital were reported.

Parents who deliver prematurely may not be aware of the benefits of human milk for their preterm babies and they commonly and understandably base their decisions on health-related issues. Staff (physicians and nurses) should stress the protective properties of human milk and recommend that parents provide human milk without necessarily making the commitment to breastfeed. The AAP further writes that the first postdelivery encounter with the physician, or as soon as it is appropriate, should include a discussion on human milk, its role in the preterm newborn’s care, and the urgency to begin expressing or pumping. The AAP considers it to be the responsibility of the nursing staff to initiate and maintain an expressing or pumping routine.⁴ The frequency and duration of milk expression directly correlate to the amount of milk produced. The parent should pump every 2 or 3 hours to mimic a baby’s natural feeding pattern. A tentative goal of 750-1000 ml per day by 10 days postpartum will help maintain milk supply throughout lactation.⁵

Colostrum
It is safe and feasible to administer oropharyngeal drops of colostrum to extremely low birth weight infants in a clinical setting. Using colostrum in this manner requires a change in thinking, to view colostrum as a potential immune therapy and not simply as a feeding. As such, the oropharyngeal administration of colostrum can be an alternative to NPO status and/or a complement to trophic feeds⁶ ⁷ in the first days of life for the ELBW infants.

Oropharyngeal administration of own colostrum is easy, inexpensive, and well-tolerated by even the smallest and sickest ELBW infants. Future research should continue to examine the optimal procedure for measuring the direct immune effects of this therapy, as well as the clinical outcomes such as infections, particularly ventilator-associated pneumonia.⁸

Donor milk
The amount of milk a premature baby needs is very small. However, when the parent of a premature baby is not able to express (enough of) their own milk, because of the optimal quality of human milk, donor milk should be obtained instead of taking recourse to human milk substitutes.

Studies⁹ have documented the following health benefits for preterm infants fed human milk:

Decreased incidence and/or severity of a wide range of infectious diseases
Decreased post-neonatal infant mortality rates
Decreased rates of SIDS in the first year of life
Reduced incidence of both type 1 and type 2 diabetes, lymphoma, leukemia, Hodgkin’s disease, overweight and obesity, hypercholesterolemia, and asthma

Donor milk can be obtained via hospitals, milk banks, or private donors (even though many hospital staff may refuse the latter). The HMBANA and NICE donor guidelines¹⁰ ¹¹ are very specific, mainly in order to protect sick and premature babies receiving this donor milk. But participants in private arrangement milksharing can similarly be screened to reduce exposure to pathogens and the milk can easily be pasteurized if necessary. Please see How can breastmilk be pasteurized? for more information on how to heat-treat. Please consult with a specialized care provider if considering donating breastmilk to a premature baby.

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There are always risks associated with feeding a baby anything other than its own parent’s healthy milk via direct nursing. When considering donor milk, parents and caretakers are balancing the benefits of superior nutrition and immunity against the risk of disease transmission. Even after donor milk is screened, some argue that pathogens can still remain¹² in the milk, and after donor milk has been pasteurized, pathogens can contaminate milk.¹³ Please see Are there risks to using donor milk? for more information on private arrangement milksharing.

Raw milk
With proper screening, raw and fresh (not frozen when possible) is a better option for babies as this milk retains all its beneficial properties. In some countries, like Norway,¹⁴ milk banks have a long tradition of using raw breastmilk, even for premature babies. Screening and testing ensure the safety of this milk, rendering pasteurizing obsolete.

Risks of heat-treating
While milk banks are available for premature (or ill infants) in various countries, using banked milk is not always a possibility for parents/caretakers because of a lack of accessibility. In the US, for instance, donor milk has a processing fee of around $4.50 per ounce¹⁵ while insurance companies only cover donor milk when it is medically necessary. Donor milk is usually also only available by prescription. In some countries, logistics may make it impossible to obtain breastmilk (distance, lack of dry ice, etc), or lack of availability.

Most milk banks use the Holder method (62.5°C/145°F for 30 minutes) to pasteurize all breastmilk. It is the method used in the studies below. Studies show that pasteurizing breastmilk has potential health consequences for premature babies. Below are a few considerations that are especially important for premature infants, though they affect term infants as well.

1. Lactoferrin
Lactoferrin is an iron-binding protein with antimicrobial activity and is part of the natural defense of the body. Lactoferrin is found in milk and many mucosal secretions such as tears and saliva.

Lactoferrin is significantly affected by the Holder method of pasteurization.¹⁶ The Holder method can destroy as much as 60% of the lactoferrin. Flash pasteurization,¹⁷ (72ºC/161.6ºF for 15 seconds) on the other hand, keeps the amount of lactoferrin intact which is extremely important for (preterm) babies for a few reasons. Lactoferrin assists in the digestion and utilization of nutrients from the milk. It also contributes to the defense of breastfed infants against pathogenic bacteria and viruses and regulates immune functions. Lastly, it is likely involved in the development of the intestinal mucosa and other organs of newborns.¹⁸ In other words, lactoferrin assists in providing adequate nutrition to infants fed with human milk while simultaneously aiding in the defense against infection, and facilitating optimal development of important normal functions in newborns.

Regarding lactoferrin and flash-heating, it is likely that the denaturation of lactoferrin due to the heat treatment does not impair its biological activity.¹⁹ Flash-heating, as well as flash pasteurizing, would, therefore, be better options for the heat-treatment of breastmilk.

2. Lipase
Lipase is an enzyme secreted in the digestive tract that causes the breakdown of fats into individual fatty acids that can be absorbed into the bloodstream.

Research shows that fat absorption and growth were reduced when preterm infants were fed pasteurized human milk as compared to raw human milk. Very Low Birth Weight (VLBW <1500 grams) infants that were fed raw milk gained more in knee-heel length compared to when they were fed pasteurized milk.²⁰

Fats are not only important for energy and growth. They are also important for brain development. To develop the high-quality myelin needed for the nerves to transmit messages to other nerves throughout the brain and body, the body needs certain types of fatty acids –linoleic and linolenic, which are found in large amounts in human milk.²¹

Lipase in human milk complements the low level of pancreatic lipase in infants, especially premature infants. Lipase aids in the absorption of fats and is unfortunately mostly deactivated by all heat treatments.²² The milk of parents of preterm babies is significantly different from that of those who deliver at term. Part of the reason that preterm milk is so important for premature babies is because the lipids in human milk also provide nutritional benefits. The fat globules in preterm milk are smaller, aiding in their absorption directly from the immature gut. Premature infants lack the enzymes and bile salts needed for the digestion of fats. However, they absorb more than 90% of the fats in human milk due to lipase.²³

Lack of lipase in pasteurized milk also has an impact on a premature baby’s immune response: the acetic acid produced by milk lipases acts against lipid-enveloped viruses, bacteria, and fungus.²⁴ Milk lipids provide an example of how an integral milk component can serve both a nutritional and a protective function.²⁵

Lipase is deactivated by heat treatment, and therefore raw (unpasteurized), fresh (not frozen when possible) human milk, from a properly screened donor, and properly handled is a better option when available.

3. Immunoglobulins
Immunoglobulins are a class of proteins produced in lymph tissue that function as antibodies in the immune response.

A study on the effects of Holder pasteurization on the milk of parents of term and preterm babies concludes that even though pasteurization reduces all factors analyzed, the total protein and IgA retained appreciable concentrations, especially in colostrum from parents of both preterm groups, indicating that pasteurized preterm milk can be a beneficial alternative for feeding the preterm infant. Higher concentrations of proteins, IgA, and IgG in raw milk of the parent’s own milk of more preterm infants may be a compensatory protective mechanism for these babies and a great effort should be made to feed the preterm with milk from their own parents.²⁶

Flash-heated human milk, on the other hand, retains most of its immunoglobulin activity and it therefore will confer similar protection from infection for the infant as would unheated milk. This suggests that flash-heated human milk is immunologically superior to human milk substitutes. Whether the decreased immunoglobulin activity of flash-heated human milk has clinical significance needs evaluation in prospective trials.²⁷

Again, raw (unpasteurized), fresh (not frozen when possible) human milk, from a properly screened donor, and properly handled is a better option when available.

4. Conclusions
Flash pasteurizing has been demonstrated to inactivate most pathogens while maintaining high levels of lactoferrin, vitamins, and immunoglobulins.²⁸

Flash-heating has also been shown to deactivate HIV and to be very beneficial in maintaining high levels of lactoferrin, vitamins, and immunoglobulins. Flash pasteurizing would be a better method than the Holder method to render breastmilk safe for term and preterm babies alike. More research is needed in order to assess the effects of flash-heating on deactivating pathogens other than HIV and 4 common bacteria.²⁹ Raw (unpasteurized), fresh (not frozen when possible) human milk, from a properly screened donor, and properly handled is a better option when available.

A review of what is currently known about the effects of Holder pasteurization on the biological activity of some of the critical components of human milk shows that there are still more questions to be answered with regard to optimal nutrition for the preterm and very low birth weight infant. Preservation of the unique components of human milk during storage of someone’s own milk, storage and processing of donor milk, and the most effective fortification methods for human milk to meet the extraordinary needs of preterm infants are important areas for continued investigation. Our current state of knowledge indicates that human milk is optimal for full-term, as well as preterm infants, although any milk may require fortification to meet the special nutritional needs of the very low birth weight infant.”³⁰

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Age-specific milk
Studies suggest that donor milk from parents of full-term infants cannot foster the same growth rate as a parent’s own milk in preterm infants. Age-specific milk for preterm babies is therefore deemed important, and when possible, milk banks process this milk separately. While much of the milk donated to milk banks comes from those who have delivered at term, they do receive milk from people who gave birth prematurely. Donor and preterm milk can be specifically requested and if available will be shipped to you. However, some of these studies were done on donor ‘drip milk,’ or milk collected from the dripping of the opposite breast while breastfeeding their own full-term infant. Drip milk has long been recognized to have lower fat content than expressed or pumped milk, since there is no active removal of the hind milk. There is also some question with regard to whether weight gain is the best measure of optimal outcome.³¹ ³² One large study found that even with slower weight gain, the human milk fed preterm infants had significantly higher IQ scores at school age.³³

Most donor milk banks today recognize the importance of using milk actively expressed or pumped to optimize fat content. Milk from parents of preterm infants (gestational age 36 weeks or less) is designated as preterm milk for the first 4 weeks of pumping. It is processed in special batches since it is higher in protein which is important for the preterm infant. Because parents of preterm infants are being more actively encouraged to provide milk for their own babies, often they have excess to donate when their babies go completely to the breast.³⁴ ³⁵

To make informed choices, we encourage donors (as well as recipients) to research their options and to investigate milk bank procedures regarding heat treatment,³⁶ storage,³⁷ distribution (Not everyone who needs breastmilk will necessarily have priority and be able to obtain breastmilk from a milk bank.³⁸ ³⁹), and usage,⁴⁰ as well as weigh the pros and cons of donating milk to a milk bank or to an individual.

A note needs to be made about Bacillus cereus. B. cereus is a spore-forming bacterium that is found in nature (soil, crops, water) and causes food poisoning. These spores are not deactivated with any heat treatment. Please see the section Bacteria for more information regarding Bacillus cereus.

If you wish to donate to a preterm baby, please see these suggested blood tests for donors and consult with a healthcare provider to see if privately donated milk is an option.

The addition of human milk fortifiers (HMF) to breastmilk for Low Birth Weight (LBW) and Very Low Birth Weight (VLBW <1500 grams) babies also deserves a closer look.

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