Human Milk Banking

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Committee on Nutrition

Human

Milk

Banking

Human milk is unquestionably the best source of nutrition for full-term infants during the first months of life. Recent publications’ have empha-sized the advantages of human milk’s biochemical composition, and particularly of its immunochemi-cal and cellular components. Renewed interest in also providing low-birth-weight infants with human milk stems partly from nutritional considerations, but more importantly from evidence that it confers some protection against infections and allergy. The degree of protection against necrotizing

enterocoli-tis is uncertain. The disease has been reported in

infants fed heat-treated breast milk,2 and it can occur in neonates fed fresh human milk. When frozen, breast milk seemingly offers little protection against necrotizing enterocolitis, although a recent paper3 does not exclude the possibility that breast milk could decrease its incidence.

MILK BANKS

Human milk has come back “into favor” in inten-sive care nurseries; consequently, there has been a resurgence of interest in human milk banks, which stopped operating in North America shortly after World War II. However, the milk bank tradition was never abandoned in certain British hospitals and in Scandinavia. The Helsinki Children’s Hos-pital experience now spans a 50-year period.4 The collection, processing, and storage of human milk may be initiated to meet the needs of low-birth-weight infants, of full-term newborn infants who temporarily cannot breast feed, or of sick infants with intractable diarrhea, the short-gut syndrome, or intolerance to cow milk or soy proteins who are responsive to other measures.

CONTAMINATION OF HUMAN MILK

An important property of breast feeding is the relative freedom from bacterial contamination of breast milk. However, bacterial contamination can be a major problem with banked human milk. The precautions which need to be taken to make breast

milk microbiologically safe require careful atten-tion, especially when breast milk is collected and stored prior to feeding. A recent outbreak of sal-monellosis has been reported in a milk bank,5 and recurrent group B streptococcal disease has been associated with the ingestion of infected breast milk.6 A variety of other bacteria, bacterial toxins, and viruses such as rubella, cytomegalovirus, and hepatitis B particles have been identified. Breast milk may also be a vehicle for transmission of herpes simplex type I.

COMPOSITION OF BREAST MILK

Human milk leukocytes are thought to constitute an important component of the antiinfective and immunologic protection conferred by breast milk.8’9 Colostral and breast milk phagocytes have a low-killing power but a considerable capacity for phag-ocytosis. They may sequester pathogens and pre-vent their attachment and subsequent colonization of the gut.’#{176}In addition to the known enteromam-mary circulation of B lymphocytes,” maternal T lymphocytes may also be absorbed intact through the gastrointestinal tract of newborn infants.’2 This possibility raises theoretical questions about the safety of feeding “fresh” (unfrozen or unheated) human milk from a mother other than the infant’s own. A syndrome resembling a graft vs host reaction has been observed in young animals fed breast milk white cells from a different species; this is not the case with human breast milk.

From a nutritional standpoint, human milk offers the reassurance of being specific, but some doubts have been expressed regarding the adequacy of protein, sodium, chloride, and calcium in human milk for small premature infants.’3”4 Although ni-trogen and mineral requirements of the small pre-mature infant are higher than in the full-term in-fants, they may be adequately met if the infant is fed by his/her mother because the composition of breast milk from mothers of young preterm infants

is substantially different from that of mothers of

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AMERICAN ACADEMY OF PEDIATRICS 855

are needed. Data on the benefits of the differences in composition of milk at term and preterm would be particularly important for extremely low-birth-weight infants. Donated human milk is usually ma-ture milk; therefore, it may not meet protein and mineral (particularly sodium) needs of the ex-tremely low-birth-weight infant.’8 A sodium

supple-ment has been recommended for these infants (P.

Sunshine, personal communication, 1979) and the possibility of adding human milk protein is under

study.

COLLECTION AND TREATMENT OF BREAST

MILK

A woman’s fresh breast milk is especially suited to her infant’s nutritional and immunologic needs; and, breast milk can be made microbiologically safe if certain precautions are taken. Recent information suggests that bacterial contamination is minimized if the donor is properly selected and trained and if the first 10 ml of milk are rejected. Some authors feel that manual expression is preferable to the suction breast pump.’9 Milk samples identified by bacteriologic screening as unacceptable must be rejected. Healthy donors are generally recruited from mothers who nurse their infants but have extra milk. The screening of potential donors, their training, and the set-up to carry out routine or spot-check bacteriologic cultures are essential compo-nents of a human milk bank.

Heat treatment is a widely used method for re-duction of bacterial contamination. However, it is important to restrict the extent and duration of heating to that required for the destruction of path-ogens. Holder pasteurization (62.5 C for 30 minutes) appears to be adequate, although 6% of the samples may not be acceptable.2#{176} Even this modest heat treatment has had significant adverse effects on the protective immunochemical constituents of human milk.8’2’ At 80 C, the ability of human milk to inhibit the growth of added bacteria largely disappears.

There is little information on the effect of heat treatment on the nutritional properties of human milk, and the results are conflicting. A recent study22 suggests that Holder pasteurization de-creases the high coefficient offat absorption of fresh human milk. The likely explanation is that heat treatment inactivates milk lipase. Nitrogen reten-tion is affected only if milk is boiled.

The storage of milk by freezing is an alternative to heating for the preservation of optimal nutri-tional value and immunologic benefits. The use of frozen storage requires more attention to bacterio-logic screening. Efforts should be made to collect clean milk with minimal bacterial contamination and to store it immediately in a freezer until it is gently thawed and fed.

There are at least three routines for collecting human milk for infants who cannot be breast fed. These include: (1) collection of milk from a mother to be supplied to her own infant, (2) collection of milk from healthy donors for feeding specific in-fants, and (3) pooling of milk from several donors.

Collection of Milk for a Mother’s Own Infant

The collection of milk for a woman’s own infant

is the most physiologic method. As previously noted, the composition of milk from the mothers of preterm infants has a higher protein, nitrogen, and mineral content than that from mothers of full-term

infants. Although these differences may meet the needs or preterm infants, critical studies are needed. Furthermore, the mother who collects her milk for her own infant is usually highly motivated and more likely to take antiseptic precautions in collecting, storing, and delivering the milk; she also is more likely to avoid exposing herself to toxic substances that might be secreted into the milk.

The greatest obstacle to the wider use of this method is a logistic one. A growing proportion of preterm infants are cared for in referral centers, which frequently are located at a considerable dis-tance from the home. This makes it difficult for some mothers to deliver milk to the hospital on a regular basis, especially if they have other children and/or heavy family responsibilities. Because most donors cannot deliver fresh milk daily, breast milk usually must be stored frozen, either in single do-nations or as pooled samples. Some mothers will experience lactation failure as they return home. This is not surprising because manual or mechani-cal expression is not as good as suckling for the stimulation of milk production and the “let down reflex.” In Finland, the percentage of mothers nurs-ing their low-birth-weight infants at 3 months of age could not be raised above 30%, even with con-siderable effort (M. A. Siimes, personal communi-cation, 1979).

The preservation of leukocytes in milk would be desirable when the mother’s milk is fed to her own infant, but there are practical obstacles to accom-plishing this. Milk cells are best preserved by col-lecting the expressed milk in plastic bags because cell counts are much higher than those retrieved from samples in glass containers.23 However, plastic bags are prone to leak and to be easily punctured.

Furthermore after 24 hours of storage, cell counts

in glass containers are higher than in plastic bags. (D. Garza, personal communication). Freezing is necessary when the interval between collection and freezing is longer than 24 hours. This procedure will

destroy viable cells.24 Storage of breast milk near body temperature is the most effective procedure to preserve viable cells, but this procedure also

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carries an increased risk of unacceptable bacterial growth. Because of these difficulties and unan-swered questions regarding white cells from the milk of a mother other than the infant’s own, a recent recommendation following a symposium on human milk suggests that attempts to preserve the cells should not influence the processing and storage conditions used for human milk.26

Collection of Milk for a Specific Infant

Providing milk from an individual donor for each infant has been proposed as a means of decreasing the risk of infection after a donor’s milk has been shown to consistently meet the criteria for numbers and types of bacteria. Disadvantages of this system are that it complicates banking procedures, results in some wastage of milk, and increases the risk of transmitting undiluted toxic substances (eg, drugs, nicotine, pesticides and environmental contami-nants) which are secreted in milk.27

Collection of Pooled Milk

Pooled milk from several donors simplifies rou-tine procedures for ensuring microbiologic safety. The mixing of milk from a group of donors also results in a more uniform nutrient content and dilutes drugs or toxins present in the milk of an individual donor. A possible disadvantage of pooled milk is the increased potential for the transmission of viral infections, particularly if the milk is frozen

only.

CONCLUSIONS

The experience of Finnish workers, as well as that of others, shows that the banking of heat-treated and frozen human milk is a practical and safe means of feeding low-birth-weight newborn infants. The continuous and exclusive use of human milk is associated with a low incidence of infection and with a rate of survival which is among the highest reported.4 The rate of growth and weight gain is also considered satisfactory, although there is some controversy about whether weight gain is quite as rapid as in formula-fed infants.28 Long-term studies should be carried out to see if these infants grow and develop as well, or better than, those on formula feedings.

It is still uncertain whether banked human milk will prove sufficiently superior to formula with re-spect to its nutritional and immunologic

character-istics to compensate for the difficulties of maintain-ing bacteriologic control and to warrant the cost of setting up and running a milk bank for premature infants. At this time, the Committee considers it optimal for mothers of low-birth-weight newborn infants to collect their milk for feeding their own

infants fresh milk. Once home, the mothers can freeze the expressed milk and organize for transpor-tation of samples on a regular basis. However, since this procedure wifi be impossible or impractical for many infants, bacteriologically safe milk from a donor seems a reasonable alternative for these in-fants.

REFERENCES

COMMITTEE ON NUTRITION

Lewis A. Barness, MD, Chairman Peter R. Dailman, MD

Homer Anderson, MD Platon Jack Collipp, MD Buford L. Nichols, Jr, MD W. Allan Walker, MD Calvin W. Woodruff, MD

1. Nutrition Committee of the Canadian Paediatric Society

and the Committee on Nutrition: Breast-feeding. Pediatrics

62:591, 1978

2. Howard FM, Flynn DM, Bradley JM, et al: Outbreak of necrotizing enterocolitis caused by Clostridium butyricum. Lancet 2:1099, 1977

3. Moriartey RR, Finer NN, Cox SF, et al: Necrotizing

enter-ocolitis and human milk. J Pediatr 94:295, 1979

4. Siimes MA, Hailman N: A perspective on human milk

bank-ing, 1978. J Pediatr 94:173, 1979

5. Ryder RW, Crosby-Ritchie A, McDonough B, et al: Human

milk contaminated with Salmonella kottbus. JAMA 238:

1533, 1977

6. Kenny JF, Zedd AJ: Recurrent group /‘3 streptococcal disease

in an infant associated with the ingestion ofinfected mother’s milk. JPediatr9l:158, 1977

7. Dunkle LM, Schmidt RR, O’Connor DM: Neonatal herpes simplex infection possibly acquired via maternal breast milk.

Pediatrics 63:250, 1979

8. Welsh JK, May JT: Medical progress: Anti-infective prop-erties of breast milk. J Pediatr, 94:1, 1979

9. Pittard WB III: Breast milk immunology: A frontier in infant nutrition. Am J Dis Child 133:83, 1979

10. Ho PC, Lawton JWM: Human colostral cells: Phagocytosis and killing of E coli and C albicans. J Pediatr 93:910, 1979

11. Goldblum RM, Ahlstedt 5, Carisson B, et al: Antibody-forming cells in human colostrum after oral immunization. Nature 257:797, 1975

12. Schlesinger JJ, Covelli HD: Evidence for transmission of

lymphocyte responses to tuberculin by breast-feeding.

Lan-cet 2:529, 1977

13. Heird WC: Feeding the premature infant: Human milk or an

artificial formula? Am J Dis Child 131:468, 1977

14. Forbes GB: Is human milk the best food for low birth weight

babies?, abstracted. Pediatr Res 12:434, 1978

15. Atkinson SA, Bryan MH, Anderson GH: Human milk:

Dif-ferences in nitrogen concentration in milk from mothers of

term and premature infants. J Pediatr 93:67, 1978

16. Gross SJ, David RJ, Bauman L, et al: Nutritional

composi-tion of human milk in mothers of preterm infants, abstracted.

Pediatr Res 13:400, 1979

17. Chan GM: Preterm and term breast milk calcium and

vi-tamin D, abstracted. Pediatr Res 13:396, 1979

18. Chance GW, Radde IC, Willis DM, et al: Postnatal growth of infants of < 1.3 kg birth weight: Effects of metabolic

acidosis, of caloric intake and of calcium, sodium and phos-phate supplementation. J Pediatr 91:787, 1977

19. Liebhaber M, Lewiston NJ, Asquith MT, et al: Comparison

of bacterial contamination with two methods of human milk

collection. J Pediatr 92:236, 1978

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distri-AMERICAN ACADEMY OF PEDIATRICS 857

bution in the mother’s milk unit of the Northern California

Transplant Bank. Presented at Nutrition for the High-risk

Infant Conference, Denver, Colorado, September 1978

21. Ford JE, Law BA, Marshall VME, et al: Influence of the

heat treatment of human milk on some of its protective

constituents. J Pediatr 90:29, 1977

22. Williamson S, Finucane E, Ellis H, et al: Effect of heat

treatment of human milk on absorption of nitrogen, fat,

sodium, calcium and phosphorus by preterm infants. Arch

Dis Child 53:555, 1978

23. Paxson CL Jr, Cress CC: Survival of human milk leukocytes.

j Pediatr, 94:61, 1979

24. Pitt J: Breast milk leukocytes. Pediatrics 58:769, 1976 25. Kleigman R, Pittard W, FanaroffA: Necrotizing enterocolitis

in neonates fed breast milk, abstracted. Pediatr Res 13:402,

1979

26. Widdowson EM: Symposium report: Protective properties

of human milk and the effects of processing on them. Arch

Dis Child 53:684, 1978

27. Committee on Nutrition of the Mother and Preschool Child:

A Selected Annotated Bibliography on Breast Feeding 1970-1977. Washington, DC, Food and Nutrition Board,

National Research Council, 1978, pp 27-33

28. Raiha NCR, Heinonen K, Rassin DK, et al: Milk protein

quantity and quality in low-birth-weight infants. I. Metabolic

responses and effects on growth. Pediatrics 57:659, 1976

29. Fomon SJ: Human milk in premature infant feeding: Report

of a second workshop. Am J Public Health 67:361, 1977

PLATO ON SLAVES AND FREEMEN

Did you ever observe that there are two classes of patients in states, slaves and freemen; and the slave doctors run about and cure the slaves, or wait for them in dispensaries-practitioners of this sort never talk to their patients individually or let them talk about their own individual complaints. The slave doctor prescribes what mere experience suggests, as if he had exact knowledge, and when he has given his orders, like a tyrant, he rushes off with equal assurance to some other servant who is ill. But the other doctor, who is a freeman, attends and practices on freemen; and he carries his inquiries far back, and goes into the nature of the disorder; he enters into discourse with the patient and with his friends, and is at once getting information from the sick man and also instructing him as far as he is able, and he will not prescribe until

he has at first convinced him. If one of those empirical physicians, who practice medicine without science, were to come upon the gentleman physician talking to his gentleman patient and using the language almost of philosophy, beginning at the beginning of the disease and discoursing about the whole nature of the body, he would burst into a hearty laugh-he would say what most of those who are called doctors always have at their tongues’ end: Foolish fellow, he would say, you are not healing the sick man but educating him; and he does not want to be made a doctor but to get well.

Submitted by Student

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1980;65;854

Pediatrics

Nichols, Jr, W. Allan Walker and Calvin W. Woodruff

Lewis A. Barness, Peter R. Dallman, Homer Anderson, Platon Jack Collipp, Buford L.