Articles & Studies

Breastfeeding: Unraveling the Mysteries of Mother’s Milk

Reproduced from Medscape Women’s Health eJournal 1(5), 1996. 
© 1996 Medscape Portals, Inc
Margit Hamosh, PhD
Georgetown University Medical Center

Abstract and Introduction

Most of the major progress in understanding the unique and complex features of human breast milk has emerged in just the past 2 decades. Since the late 1970s, key research has examined such aspects as the composition of breast milk, effects of maternal and environmental factors on human milk, and the effect of human milk on the infant, including the protection against disease that breast milk can confer on the newborn. The composition of human breast milk includes growth factors, hormones, enzymes, and other substances that are immune-protective and foster proper growth and nutrition in the newborn. Research suggests that lactation is robust and that a mother’s breast milk is adequate in essential nutrients, even when her own nutrition is inadequate. Mature breast milk usually has constant levels of about 7g/dL carbohydrate and about 0.9g/dL proteins. But the composition of fats essential for neonatal growth, brain development, and retinal function varies according to a woman’s intake, the length of gestation, and the period of lactation. Vitamins and minerals also vary according to maternal intake. But even when these nutrients are lower in breast milk than in formulas, their higher bioactivity and bioavailability more nearly meet the complete needs of neonates than do even the best infant formulas. Also, in many instances human milk components compensate for immature function, such as a neonate’s inability to produce certain digestive enzymes, immunoglobulin A (IgA), taurine, nucleotides, and long-chain polyunsaturated fatty acids.

Introduction

Even when a mother’s own supply of nutrients and energy is limited, she still is able to produce breast milk of sufficient quantity and quality to support the growth and health of her infant. This finding that "lactation is robust" is one of several discoveries to emerge in recent years.[1] The quest to better understand the complex features of human breast milk has been building in the past 2 decades, as evidenced by the growing number of international meetings, expert work groups, and publications focusing on human breast milk. Since the late 1970s, key research has addressed such topics as analyzing human milk,[2-4] identifying how maternal and environmental factors affect breast milk,[5] and determining the effect of human milk on the infant,[6,7] including the protection against disease that breast milk can confer on the newborn.[8]

Human milk, like the milk of many other mammals, is specifically adapted to the needs of the newborn. Before birth, the mother transfers nutrients and bioactive components through the placenta[9]; after birth, these substances are transferred through colostrum and milk. In contrast to infant formula, human milk offers the infant nutrients with high bioavailability as well as a large number of bioactive components that confer immune and nonimmune protection against pathogens in the infant’s environment. Also, in many instances human milk components compensate for immature function, such as a neonate’s inability to produce certain digestive enzymes, immunoglobulin A (IgA), taurine, nucleotides, and long-chain polyunsaturated fatty acids (LC-PUFA), among other substances. Because many of these components remain intact during pasteurization, it is more advisable to feed pasteurized human donor milk to infants whose mothers are unable to nurse than it is to substitute formula.[1] Its bioactive components make human milk superior to even the best infant formulas.

Milk Volume and Composition

Volume. Milk volume is relatively constant irrespective of maternal nutritional status (Fig. 1). In general, healthy infants consume an average of 750-800mL milk daily for the first 4-5 months after birth (range, 450 to 1200mL/day).[1,10,11] Similar findings were reported from developing countries where maternal nutrition is sometimes subject to greater seasonal variation and may be less adequate compared with industrial countries.[1,11] Increasing the intake of fluid does not seem to affect milk volume.[10] Therefore, lactating women should maintain adequate fluid intake but should not attempt to boost milk volume by consuming excess fluids.[1]
mother and child breastfeeding
Figure 1. In general, healthy infants consume 450 to 1200mL/day first 4-5 months after birth. Milk volume is relatively constant irrespective of maternal nutritional status. Photo courtesy of Susanrachel Condon.

Major nutrients. Lactose, 5.5-6.0g/dL, is the most constant nutrient in human milk (Table I). Its concentration in breast milk is not affected by maternal nutrition.

Proteins amount to about 0.9g/dL in mature milk.[12]Recent studies comparing the impact of nutrition on lactation in industrialized and developing countries suggest that neither maternal diet nor body composition affects milk protein level.[1] However, limited data from earlier studies seem to indicate that short-term, high-protein diets can increase the protein and nonprotein nitrogen content of human milk,[13] while limiting maternal food intake can lead to lower milk protein levels.[13-15]

The majority of milk proteins provide the newborn with immune and nonimmune protection from infection. These proteins--immunoglobulins A, G, and M; lactoferrin; and lysozyme--have various functions in the newborn.[16] Early studies suggested that the level of these protective proteins in milk is affected by maternal diet, but more recent research suggests that immunoglobulins might be stable for a wide range of diets.[17-20]

Fat. While the amount and composition of carbohydrate and protein remain relatively constant in mature human milk, the composition of fat is highly variable and is affected within hours and to a large extent by maternal nutrition intake.[21] Gestation, lactation, parity, milk volume, caloric and carbohydrate intake, and weight changes are among the maternal factors that can alter the fat content and composition of breast milk. Specifically, phospholipid and cholesterol content are higher in colostrum preterm than term breast milk. Also, long chain polyunsaturated fatty acids (LC-PUFA) are higher in preterm and transitional milk and remain high for the first 6 months in women who deliver preterm. In term milk, on the other hand, LC-PUFA declines throughout the first 6 to 12 months of lactation. The endogenous synthesis of fatty acids (FA) declines with parity, most notably after 10 births, but FAs (C6-C16) rise with a high-carbohydrate diet. Palmitic acid (C16) content of breast milk increases in a low-calorie diet. Weight gain during pregnancy is positively associated with higher milk fat content. During infant feedings, fore milk has less fat content than hind milk. Also, the higher the volume of breast milk, the lower the milk fat concentration.[92] The lengths of both gestation and lactation affect phospholipid and cholesterol, the lipids that constitute the milk fat globule membrane.[22]In the early stage of lactation, because the milk fat globules are much smaller than in mature milk,[23,24] the total "membrane" lipid level is higher in colostrum and transitional milk than in mature milk. The period of colostrum lasts less than 10 days, but during this short time the higher lipid levels are beneficial in such processes as neonatal cell membrane production needed for growth, brain development, and bile salt synthesis. LC-PUFAs--C20:4n6 and C22:6n3, arachidonic, and docosahexaenoic acids, respectively--are milk fats essential for neonatal growth, brain development, and retinal function.[25,26] These fatty acids are stored in the fetus only in the last trimester of pregnancy; therefore, preterm infants are born with low reserves of LC-PUFA, and their best source for these essential fatty acids is human milk. LC-PUFA levels normally decrease in breast milk during lactation, but in women who have delivered infants before term, the levels remain constant in preterm milk for at least 6 months[27]. Holman and colleagues[28] have reported that levels of LC-PUFA often decline in pregnant and lactating women, suggesting that there is a preferential transfer of these essential fatty acids from mother to fetus or to the newborn through milk, even at the cost of possible depletion of maternal reserves. Depletion of maternal reserves might suggest the need for supplementation of pregnant and lactating women with LC-PUFA.

Milk fat content changes dramatically during each feeding[29,30] and fat composition is markedly affected by the maternal diet.[31] Some studies have shown that the mechanism for endogenous synthesis of fatty acids (ie, mainly medium chain fatty acids) seems to become exhausted in women of very high parity[32]; that infants who receive milk with low fat content (ie, less than 3.0 g/dl when the norm is 3.5 to 4.5 g/dl) tend to nurse more frequently and for longer time periods, thereby causing an increase in milk volume[33]; and that there is a strong positive relationship between weight gain during pregnancy and milk fat content.[34]

Vitamins and minerals. The vitamin content of human milk depends on the mother’s vitamin status; when maternal intake of specific vitamins is chronically low, these vitamins in turn are found in low levels in the milk. Vitamin supplementation raises vitamin concentrations in milk. Water-soluble vitamins in milk are generally more responsive to maternal dietary intake than fat-soluble ones.[1]

The relationship between maternal intake of vitamins and their concentration in milk varies according to the specific vitamin. For example, excess vitamin C intake does not further increase the level in milk (above that associated with adequate intake), whereas vitamin B6 concentrations in milk continue to rise with higher intakes. Folate levels in milk remain normal even at the expense of maternal folate stores and do not decrease until the latter are depleted.[1] Based on infant needs and the concentrations of fat-soluble vitamins in human milk, the Institute of Medicine (IOM) advises that in the US all newborns receive 0.5-1.0mg vitamin K by injection or 1.0-2.0mg orally immediately after birth.[1,10]Infants should receive 5.0-7.5ug vitamin D per day if exposure to sunlight seems inadequate.

The concentration of trace minerals (iron, copper, zinc, selenium) varies as a function of length of lactation. Concentrations of iron[35,36] and fluoride[37] in milk seem to be independent of maternal nutrition. Concentrations of manganese,[38] iodine,[39] and selenium[40] depend on maternal nutrition. Iodine is unique among trace elements in that it is avidly accumulated by the mammary gland[1].

Because of the high bioavailability of iron in human milk, exclusively breast-fed infants do not need iron supplements during the first 6 months of life. When supplementary foods are introduced (as recommended after 4-6 months of exclusive breast-feeding), iron supplements should be added to the infant’s nutrition[35, 36]. It is recommended that breast-fed infants receive supplemental fluoride if the water supply in the area has only low levels (<0.3ppm).

It is important to assess not only the concentration of milk components but also the amount delivered to the infant. Thus, while some milk components are present at a higher concentration in colostrum than in milk, one has to consider the marked differences in volume: colostrum amounts to about 100mL/day, whereas average milk volumes are 750-850mL/day.

Bioactivity of Human Milk

Breast milk provides not only essential nutrients but also a great number of other specific functions in the newborn. For example, major nutrients, protein, carbohydrate, and fat, in addition to serving as building blocks for the infant’s tissue, carry out anti-infective as well as nutrient-enhancing functions, such as transporting essential elements and aiding digestion. Furthermore, even when concentrations in human milk are markedly lower than in bovine milk or formula, nutrients from human milk might have much greater bioavailability for the infant because of specific biologic factors, such as the infant’s receptor-mediated uptake of iron from human milk. Thus, in spite of a relatively low concentration of some nutrients, human milk might be superior to other nutrient sources in providing these nutrients to the infant. The apparently lower concentration of some nutrients in human milk such as vitamin D, pantothenic acid, and folate, might be due to the fact that they are bound to other components or, lower concentrations may be due to shifts from the aqueous phase to the fat phase of milk upon standing after the milk has been expressed from the breast (vitamin D).

Immune and Nonimmune Protecting Agents

All proteins in human milk have bioactive functions in addition to providing amino acids for protein synthesis by the newborn. Whey proteins, for example, have been reported to provide immune and nonimmune protection.[41,42] Recently, casein has been shown to prevent the attachment of Helicobacter pylori to human gastric mucosa.[43]

Most proteins in human milk are heavily glycosylated[44] and are therefore resistant to proteolysis both after ingestion by the infant[42,45] and after short-term storage (4-24 hours) at low to moderate ambient temperatures (15deg.-25deg.C).[46,47]

Early in studies of human milk, researchers became aware that certain substances--most notably, IgA, lysozyme, and lactoferrin--that are abundant in human milk (compared with bovine milk)[41] might protect the infant from infection.[47] This observation has progressed within the last 2 decades to a fuller appreciation of several characteristics of breast milk’s protective features:

  • Immunoprotective substances act at mucosal sites.
  • Because of their resistance to digestive enzymes, protective factors are well adapted to persist in the hostile environment of the gastrointestinal tract.
  • They kill certain bacterial pathogens synergistically.
  • Protection is achieved without triggering inflammatory reactions.
  • The daily production of many immunoprotective factors changes as lactation proceeds.
  • The secretion of many soluble defense agents by the mammary gland is inversely related to the capacity of the recipient infant to produce them at mucosal sites.[41, 49-51]
The presence in milk of immunomodulators that fine-tune the interrelationships among the various protective agents has recently been reported and is currently being investigated (Table II).[52] Secretory immunoglobulin A (sIgA), dimeric IgA coupled to the secretory component, is the main immunoglobulin in human milk. IgG and IgM are also present in milk, but at much lower concentrations. The changing concentration of these immunoglobulins in milk provides an example of the interaction between milk components and the functional development of the infant: while IgG and IgM rise rapidly after birth, the newborn maintains low levels of endogenous IgA during the first year of life. IgA is produced in the mammary gland in B cells, which originate at maternal sites of high environmental pathogen exposure (eg, the small intestine or respiratory tract), and therefore protects the infant against pathogens present in the immediate environment.

Table III summarizes the enteric and respiratory pathogens against which the infant is protected by specific IgA antibodies in human milk. IgA is resistant to proteolysis, acts at mucosal surfaces, and protects by noninflammatory mechanisms; all of these properties enable efficient action in the infant.

Human milk lacks inflammatory mediators, and contains anti-inflammatory agents such as antiproteases, antioxidants, and enzymes that degrade inflammatory mediators and modulators of leukocyte activation (Table IV).[49] Furthermore, IgE (the principal immunoglobulin responsible for immediate hypersensitivity reactions), basophils, mast cells, eosinophils (the principal effector cells in these reactions), and the mediators from these cells are absent in human milk. Immune and nonimmune protecting agents are present in milk throughout lactation and some, such as lysozyme, are present at higher concentrations during prolonged lactation than during the early stages. Therefore, although it is strongly advocated that breast-fed infants receive food supplements after 4 to 6 months of exclusive breast-feeding, it is advisable to breast-feed for longer periods in geographic areas where the environment may be contaminated with pathogenic microorganisms, in order to provide the infant and toddler the benefits of milk-borne protective agents.

Studies also indicate that a glycoconjugate present in human milk, but absent in either human serum or bovine milk, inhibits the binding of HIV envelope glycoprotein (gp120) to the CD4 receptor of T lymphocytes.[53,54]

In addition to soluble antigens and anti-infective agents, human milk contains leukocytes; the majority (90%) are neutrophils and macrophages. Lymphocytes account for approximately 10%. The number and type of leukocytes change with duration of lactation. Most of the lymphocytes in milk are T cells. The proportions of CD4 (helper) to CD8 (suppressor/cytotoxic) cells in human milk are similar to those in blood. Cytokines in human milk (eg, TNF-alpha and IL-1-beta) have been shown to enhance the anti-infective function of milk leukocytes. Milk macrophages might participate in the process of immunogenesis in the infant.

The immune and nonimmune protection provided by milk results in a lower incidence of necrotizing enterocolitis[55] and other gastrointestinal and respiratory infections in breast-fed infants than in formula-fed infants[56]. The incidence of otitis media is also lower than in formula-fed infants. In addition to protection against some infectious diseases, breast-fed infants might also be protected at later ages from diseases that are sequelae of infectious insults (eg, insulin-dependent diabetes mellitus, lymphoma, and Crohn’s disease). Immune factors provided by human milk that compensate for their delayed production by the infant are summarized in Table V.

Oligosaccharides (which amount to 1.0-1.5g/100mL of human milk),[53]glycoconjugates, mucins, and glycolipids act as receptor analogs and thereby inhibit the binding of enteric and respiratory microorganisms and their toxins.[57] In addition, the hydrolysis of milk triglycerides (the major component of milk fat) during digestion in the stomach and intestine[59]produces free fatty acids and monoglycerides that have been shown to have antiviral, antiprotozoan, and possibly also antibacterial activity.[60]

Growth Factors and Hormones

The presence of growth factors and hormones in milk and their function has been known for some time (Table VI, VII).[61-64] Interestingly, the concentration of many growth factors and hormones is higher in a woman’s milk than in her plasma. The milk hormones, however, often differ in structure from their maternal serum counterparts, suggesting modification (often post-translational processing such as glycosylation) within the mammary gland. These glycosylated forms often are difficult to detect by standard RIA techniques and have to be quantitated by specific bioassays.[62] The stronger glycosylation protects these bioactive components during passage through the gastrointestinal tract and probably enables the newborn to absorb growth factors and hormones from mother’s milk.

It appears that variants of prolactin are present in the circulation of the newborn and that the prolactin acquired from breast milk, and not endogenous prolactin secreted by the newborn’s pituitary gland, is essential for the normal development of the neuroendocrine regulation of prolactin in the newborn.[62,65]

Many hormones act in the newborn. While the exact mechanisms of uptake from milk and their mode and site of action in the newborn are known for some, further study is needed to identify these mechanisms for most hormones. Agents in milk seem to stabilize hormones in the gastrointestinal tract of the newborn.

In addition to prolactin, other hormones such as progesterone are present in different form in breast milk than in maternal serum. Transfer of these hormones from milk to infant was documented in some studies directly; in other studies, this transfer is inferred from the documentation of higher serum level of the hormone--for example, thyrotropin releasing hormone (TRH) and somatostatin--in breast-fed than in formula-fed newborns[61]. The milk hormones may also be modified as they pass through the gastrointestinal tract and prior to release into the newborn’s blood.

Enzymes

Human milk contains a great number of enzymes, many of which have specific transport functions (Table VIII). For instance, xanthine oxidase acts as a carrier of iron[65] and glutathione peroxidase carries selenium.[66] Although proteases are present in human milk, it is not known how much of that activity is expressed because of the antiprotease activity of human milk itself.[66] One can postulate that antiproteases might protect the mammary gland from local proteolysis (caused by leukocytic or lysosomal proteases) and might prevent the proteolytic breakdown of milk proteins, many of which have to reach the infant intact (eg, immunoglobulins, digestive enzymes). The antitryptic and antichymotryptic activity of human milk might prevent the absorption of endogenous and bacterial proteases in infants and thereby contribute to the passive protection of extraintestinal organs such as the liver.[67] The high activity of antiproteases in colostrum coincides with the period of greatest transfer of nonimmunoglobulin protein from the intestine to the systemic circulation of the newborn.

The digestive enzymes in milk (amylase and digestive lipase) act in the newborn to compensate for immature pancreatic function. These enzymes are remarkably stable for years in milk stored at low temperature (-20deg.C or -70deg.C). Moreover, activity is unchanged after storage for 24 hours at 38deg.C. The stability of enzymes and of other proteins in milk might be due to the antiprotease activity of milk. Furthermore, many enzymes are stable in the gastrointestinal tract of the newborn.

Amylase,[68] an enzyme identified in milk more than a century ago,[69]may be more important to the infant after initiation of starch supplements[70] or when formula that contains oligosaccharides hydrolyzed by amylase is fed to partially breast-fed infants. Amylase activity in the duodenum of the newborn is only 0.2% to 0.5% of the adult level. At the time of supplementation (after 4 to 6 months of exclusive breast-feeding), the infant is still deficient in endogenously produced amylase.[71] The latter secreted from salivary glands and pancreas does not reach adequate levels until 2 years after birth. Other infants and toddlers who might benefit from milk amylase are those with pancreatic insufficiency caused by diseases such as cystic fibrosis[72] or malnutrition.[73-75] Because of the potential of bile salt-dependent lipase in milk[76] to compensate for the low pancreatic lipase in the newborn,[77,78] this enzyme has received great attention in the past decade.[44,66] The characteristics of the digestive enzymes of human milk are summarized in Table IX.

Other Essential Components in Human Milk

Several milk components are essential because they have to be provided to the newborn, while older children and adults have the ability to synthesize these components. Among these are carnitine,[79] taurine,[80]and LC-PUFAs[26] that are produced by elongation and desaturation of the precursor fatty acids, linoleic (C 18:2, n-6), and linolenic (C18:3, n-3) acids, and nucleotides[81] that have to be provided to the intestine and lymphatic tissues because they cannot be synthesized either from the diet or de novo in other organs.[82] The need for these essential components might be even greater in premature infants who are born before fetal intrauterine reserves have been laid down.

The breakdown of milk casein produces beta-casomorphins; these short peptides have been shown to affect a variety of physiologic systems.[83]Because they are opioid agonists, these peptides also have behavioral effects, such as lowering response to pain and elevating mood, that can affect the nursing mother or the newborn. Most of the effects of the beta-casomorphins have been studied in such animals as rats, pigs, and chickens[83].

Human Milk After Preterm Delivery

The milk produced by women who deliver prematurely differs from that produced after a full-term pregnancy. Specifically, during the first month after parturition, preterm milk maintains a composition similar to that of colostrum. Colostrum, secreted during the first few days after parturition, contains higher concentrations of protein (including higher levels of protective proteins such as secretory IgA, lactoferrin, and lysozyme), sodium, and chloride, and contains lower amounts of potassium, carbohydrate, fat, and certain vitamins. While the transition from colostrum to mature milk is rapid after full-term pregnancy, it proceeds much more slowly after premature delivery.[84]

Some of the nutritional needs of preterm infants, therefore, cannot be met by feeding the preemie breast milk only. While the mother’s own preterm milk is preferable to donor-banked full-term milk, either diet has to be supplemented with protein, calcium, and phosphorus in the preterm infant.[85] However, given the many benefits to the preterm infant that accrue from the mother’s own milk, efforts should be made to encourage mothers of preterm infants to breast-feed, even if during the early stages this might necessitate milk pumping while the infant is hospitalized or is too immature to nurse.

Long-Term Effects of Breast-feeding

Human milk not only is beneficial during infancy,[1,2,7,8] but it also may protect the child from chronic diseases that develop at later ages, such as Crohn’s,[86] diabetes mellitus,[87] and lymphomas.[88] Also, cognitive development, assessed at 7.5-8.0 years of age, seems to be affected by early diet in the preterm infant. A significantly higher score on the Wechsler Intelligence Scales for Children-Revised (WISC-R) was found in children fed expressed human milk than in those fed formula in early infancy.[89,90] Similar findings have been reported for full-term infants.[91]

Conclusion: Continuing the Progress in Understanding and Promoting Breast-feeding

Given the short-term and long-term benefits of breast-feeding, many working women continue to breast-feed after returning to work. Collection and proper storage of milk in the workplace might not always be easy, because it may be difficult to find a quiet, isolated place where the mother can pump milk, or a refrigerator for milk storage. However, one study showed that milk can be safely stored for up to 24 hours at 60deg.F,[47] a temperature that can be maintained in a styrofoam box with a frozen ice pack. Efforts should be made to make the workplace an easier environment in which women who choose to breast-feed can do so.

We have just begun to assess the many components in human milk and their interaction with the infant. Much work lies ahead to understand in depth the immediate and long-term effects of feeding mother’s milk to newborns. As researchers continue to discover the unique features of breast milk, clinicians need to encourage the practice for the sake of the benefits breast-feeding can bring to both mothers and infants.

Tables

Table I. Concentrations of Nutrients in Mature Human Milk

 

Major nutrients g/liter
Carbohydrate 72.0±2.5
Protein 10.5±2.0
Fat 39.0±4.0
Macronutrients
Minerals mg/liter
Calcium 280±26
Chloride 420±60
Magnesium 35±2
Phosphorus 140±22
Potassium 525±35
Trace Elements ug/liter
Chromium 50±5
Copper 250±30
Fluoride 16±5
Iodine 110±40
Iron 300±100
Manganese 6±2
Molybdenum NR
Selenium 20±5
Zinc 1200±200
Vitamins
Fat-soluble mg/liter
Vitamin A, RE* 670±200 (2230 IU)
Vitamin D 0.55±0.10
Vitamin E 2300±1000
Vitamin K 2.1±0.1
Water-soluble mg/liter
Vitamin B6 93,000±8,000
Vitamin B12 0.97
Biotin 4±1
Vitamin C 40,000±10,000
Folate 85±37
Niacin 1500±200
Pantothenic acid 1800±200
Riboflavin 350±25
Thiamin 210±35

Reprinted from Hamosh et al: Nutrition During Lactation, (1991, p 116), Copyright (c) 1991, National Academy Press.Data (means ± SD); IU = international units; NR = not reported; RE = retinol equivalents.


Table II. Cytokines in Human Milk: Mean Concentrations and Potential Functions*

 

Cytokines Possible Functions Concentrations
IL-1b Activates T cells ~ 1130pg/mL
IL-6 Enhances IgA production ~ 151pg/mL
IL-8 Chemotaxin for neutrophils/T cells ~ 3500pg/mL
IL-10 Decreased inflammatory cytokine synthesis ~ 3500pg/mL
TNF-a Increased secretory component production ~ 620pg/mL
TGF-b Enhances Ig isotype switching to IgA+ B cells ~ 130pg/mL
M-CSF Induce proliferation and differentiation of macrophages ~ 2000-9000 U/mL

*Milk collected during the first several days of lactation. Data are mean values.
From Goldman AS, et al.[42]


Table III. Enteric and Respiratory Pathogens Commonly Targeted By Secretory IgA Antibodies Found in Human Milk

 

Enteric Pathogens Respiratory Pathogens
* Bacteria, Toxins, Virulence Factors
Clostridium difficile
Escherichia coli
Salmonella spp
Shigella spp
Vibrio cholerae
* Parasites
Giardia lamblia
* Viruses
Polioviruses
Rotaviruses
* Bacteria
Haemophilus influenzae
Streptococcus pneumoniae
Klebsiella pneumoniae
* Viruses
Influenza viruses
Respiratory syncytial virus
* Fungi
Candida albicans
* Food Proteins
Cow’s milk
Soy

From Goldman AS, Goldblum RM. Immunologic systems in human milk: Characteristics and effects, in Lebenthal E (ed): Textbook of Gastroenterology and Nutrition in Infancy, ed 2. New York, Raven Press, 1989, pp 135-142.


Table IV. Anti-Inflammatory Components in Human Milk

 

Component Enzymes Function
Catalase Degrades hydrogen peroxide
Histaminase Degrades histamine
Arysulfatase Degrades leucotrienes
Antioxidants
a-Tocopherol
Cysteine
Ascorbic acid		 Scavengers of oxygen radicals
Antiproteases
a -1-antitrypsin
a -1-antichymotrypsin		 Neutralize enzymes that act in inflammation
Prostaglandins
PG-E2
PG-F2		 Cytoprotective

Reprinted from Acta Paediatr Scand (1986; 689), Copyright (c) 1986, Scandinavian University Press.


Table V. Immune Factors in Human Milk that Compensate for Delayed Production in Infants

 

Immune Factors in Human Milk When Immune Factors Mature in the Infant
Secretory IgA (sIgA) ~ 4-12 months
Full antibody repertoire ~ 24 months
Lysozyme ~ 1-2 years
Lactoferrin ?
Interleukin-6 ?
PAF-acetylhydrolase ?
Memory T cells 2 years

Reprinted from Pediatr Infect Dis J (1993; 12:664-672), Copyright (c) 1993, Williams and Wilkins.


Table VI. Growth Factors in Human Colostrum and Milk

 

Growth Factor Colostrum Milk
EGF* 6-73 nM 3-19 nM
NGF Not quantified  
Insulin* 21.5±5mg/L 2.6±0.3mg/L
IGF-I 10.9±5.3mg/L 7.1-19.1mg/L
IGF-II NR 2.7±0.7mg/L
Relaxin 327±110mg/L 509±5.3ng/L
TGF-a 2.2-7.2mg/L 0-8.4mg/L

* EGF concentration higher in preterm colostrum and milk, insulin concentration lower in preterm colostrum and milk than in term milk. From Donovan et al. [64]


Table VII. Function of Milk-Growth Factors and Hormones in the Mammary Gland and Newborn

 

Growth Factor/Hormone Maternal Mammary Gland Newborn
PRL Maintenance of lactation Neuroendocrine and immune system
Corticosterone Synthetic capacity (enzymes, specific proteins, etc.) Response to stress in the adult
Insulin Growth via IGF-II or IGF-I Neonatal glycemia
IGFs Growth and (?) differentiation of gland GI growth, affect IGF receptors in intestine (?) systemic growth effects
Relaxin Growth and differentiation  
EGF, TGF-a Growth GI growth, gut closure, eye opening
TGF-b Inhibits growth Inhibits enterocyte growth in ovarian GnRH receptors
GnRH   (?) GH secretion
GRH   (?) GH secretion
TRH   (?) TSH secretion
PTHrP (?) Ca/P/Mg in milk  
Salmon calcitonin-like peptide PRL inhibiting factor  
Erythropoietin   Stimulates erythropoiesis
Prostaglandins Cytoprotection for intestine  

EGF: epidermal growth factor; IGF: insulin like growth factor; PRL: prolactin.
From Grosvenor et al.[62]


Table VIII. Functions of Enzymes in Human Milk

 

Function Enzyme(s) Process(s)
Biosynthesis of milk components in the mammary gland Phosphoglucomutase Synthesis of lactose
Lactose synthetase Synthesis of lactose
Fatty acid synthetase Synthesis of medium-chain fatty acids
Lipoprotein lipase Uptake of circulating triglyceride fatty acids
Digestive function in the infant Amylase Hydrolysis of polysaccharides
Lipase (bile salt-dependent) Hydrolysis of triglycerides
Proteases* Proteolysis (not verified)
Transport in the infant Xanthine oxidase Carrier of iron, molybdenum
Glutathione peroxidase Carrier of selenium
Alkaline phosphatase Carrier of zinc, magnesium
Preservation of milk components Antiproteases Protection of bioactive proteins (ie, enzymes and immunoglobulins)
Sulfhydryl oxidase Maintenance of structure and function of proteins containingS-S bonds
Anti-infective agents Lysozyme Bactericidal
Peroxidase Bactericidal
Lipases (lipoprotein lipase, bile salt-dependent lipase) Release of free fatty acids that have antibacterial, antiviral,and antiprotozoan actions
Protection against enterocolitis PAF-AH Hydrolysis of platelet necrotizing activity factor
*It is not known whether the proteolytic enzymes of milk are active because of possible interaction with milk antiproteases. PAF-AH = Platelet activity factor acetyl hydrolase.
From Hamosh.[66]


Table IX. Characteristics of Milk Enzymes Active in Infant Digestion Enzyme

 

Characteristic Maternal factors Amylase Bile salt-dependent lipase
High parity (>10) Low activity ?
Malnutrition ? Decrease in activity
Diurnal and within feed activity Constant Constant
Pattern of secretion
Prepartum ? Present
Colostrum Colostrum greater than milk Colostrum lower than milk
Milk after preterm (PT) and term (T) delivery Equal activity PT and T Equal activity PT and T
Weaning ? Activity constant independent of milk volume
Distribution in milk Aqueous phase Aqueous phase
Effect of milk storage Temperature
Cold: -20deg.C to -70deg.C Stable Stable
Warm: +15deg.C to +38deg.C Stable (at least 24 hrs)  
Stable (at least 24 hrs)    
Effect of pH
Low pH (pH>3.0) (passage through stomach) Stable Stable
pH optimum 6.5-7.5 7.4-8.5
Enzyme character Identical to salivary amylase isozyme Identical to pancreatic carboxyl ester lipase
Evidence of activity in infant’s intestine Yes Yes
Presence in milk of other species ? Yes, in primates and carnivores

From Hamosh.[66]

 

References

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Dr. Hamosh is a professor of pediatrics and chief, Division of Developmental Biology and Nutrition, Department of Pediatrics, at Georgetown University Medical Center in Washington, D.C.

Studies on Human Lactation

The Development of the Computerized Breast Measurement System

by D. B. Cox, R. A. Owens* and Peter E. Hartmann

INTRODUCTION

Mammary gland physiology has been extensively investigated in both dairy and laboratory species. However, in women little is known about the control of breast function, due to the lack of suitable measurement techniques. Conventional test-weighing techniques measure the amount of milk transferred to the infant. However, since babies that are breastfed on demand drink to appetite and usually do not empty the mother’s breasts at each breastfeed, test weighing does not necessarily measure the synthetic activity of the breast (Daly and Hartmann, 1995). We reasoned that the increase in breast volume from the end of one breastfeed to the beginning of the next, divided by the time between breastfeeds, provides a measure of the mother’s short-term rate of milk synthesis. Following the exploration of a number of photo-topographic systems, we developed a non-invasive Computerized Breast Measurement (CBM) system capable of quantifying changes in breast volume from one breastfeed to the next.

This paper describes the conception of the volume measurement system and its evolution. We highlight the principle findings from studies using the CBM system, and explain how they relate to the understanding of breast physiology.

CONCEPTION OF THE IDEA

Western Australia has a large mining industry, and for many years mining surveyors, here and elsewhere, have quantified large stockpiles of ore by stereoscopic aerial photography. Stockpiles of ore and ore-containing mountains, viewed from an altitude of about 1000 m, have similar characteristics to a breast viewed from a distance of about one metre.

Stockpiles of salt and a mineral containing mountain
Stockpiles of salt (left) and a mineral containing mountain (right), that provided
the inspiration to measure breast volume stereoscopically.

This lead to the concept of measuring the volume of the breast stereoscopically. Working in collaboration with a local mining company (Associated Surveys International Pty, Ltd), the volume of volunteers' breasts were measured. Unfortunately the breast was smoother and had a more uniform colour than ore bodies, presenting problems for the stereoscopic measurement technique. Nevertheless, it was possible to calculate breast volume (albeit in metric tonnes!).

MOIRE TOPOGRAPHY

Following the success of the stereoscopic measurement of breast volume, Arthur et al. (1986) investigated breast volume, this time using Moire fringe patterns to create topographic maps of the breast.

Moire fringe patterns projected onto a breast
Moire fringe patterns projected onto a breast.
These patterns were formed by projecting light through a screen of closely spaced moving wires.

While Moire topography allowed accurate measurement of breast volume, slow data processing made this method impractical for the measurement of large sample numbers. Also, the method required the formation of uninterrupted fringe patterns on the breast and, hence, was limited to the study of smaller breasts (Figure 2), since large breasts exhibit sharp depth discontinuities at the base and sides and these discontinuities cause the fringe patterns to break up. Therefore, a topographic system that could rapidly determine breast volume, on a wide range of breast sizes, was required. These conditions have been satisfied by the development of the CBM system.

The CBM system.
The CBM system

COMPUTERISED BREAST MEASUREMENT SYSTEM

The CBM system consists of a repositioning frame which provides physical constraints to enable the mother to return to approximately the same position each time a measurement is made (Figure 3). Precise repositioning for subsequent measurements is achieved by using a video mixer so that the mother can view a video monitor and match her live image to an overlaid image stored from her initial measurement. In order to measure the changes in breast volume a circle, encompassing all of the breast tissue, is drawn around the breast with non-toxic, black acrylic paint.

The CBM system is both a hardware and software development of the ShapeC Measurement System (Alexander & Ng, 1987), which utilises the apparent distortion of horizontal coded light stripes to make volume measurements. A sequence of structured light patterns is projected on to the woman’s breast so that interrupted stripes can be tracked by the computer program.

The CBM system (inset panel), surrounded by images of a breast with each of the coded light striping patterns projected onto it
The CBM system (inset panel), surrounded by images of a breast with each of the coded light striping patterns projected onto it. The final image that is captured and used for the topographic reconstruction contains no stripes.

The images are captured over a period of 0.3 second by a CCD camera linked to a frame grabber. We now have two projector-camera pairs coupled to the system so that the breast can be sequentially viewed from above and below (Figure 3). This improves the precision of measurements for women with larger breasts. When the breast is viewed by the CCD camera from a position offset (by 15o in our system) from the plane of the light stripes (Figure 4), the parallel pattern of stripes is distorted by the curvature of the breast and a topographic map is created.

Three-dimensional topographic maps of a breast
Three-dimensional topographic maps of a breast viewed from two angles.
These surface maps were constructed as described by Cox et al. (1994).

From the apparent distortion of the light stripes, the x, y, and z co-ordinates of individual points which track the light stripes are calculated by active triangulation. The aggregate of these points describes the three dimensional surface of the breast. Relative breast volume is then simply calculated by integration of the region under the surface curve, and within the black painted circle that surrounds the breast

View of the breast from an angle offset from the plane of light
(Huynh et al., 1990) View of the breast from an angle offset from the plane of light.
Note the apparent distortion of the stripes as they fall on the breast. Also note the hand-applied black acrylic paint circle that delimits the tissue for volume determination.

Thus, the CBM system does not determine absolute breast volume, but rather measures a relative volume, that is, the volume of tissue enclosed within the black painted circle. It is assumed that when synthetic tissue is making and secreting milk, the volume of non-breast tissue remains the same.

VALIDATION OF MEASUREMENTS

The CBM system has been designed to maximise accuracy and sensitivity for the measurement of changes in breast volume. The validity of using the CBM system for these measurements was confirmed by relating the change in breast volume from before to after a breastfeed (measured by the CBM system) to the mass of milk removed from the breast over the same interval (measured by test weighing). These two parameters were strongly related (r^2=0.93), for volumes ranging up to ~200 mL (Daly et al., 1992). Consequently, it was concluded that any increase in breast volume after a breastfeed must be related to the volume of milk that is synthesised, and therefore the increase in breast volume divided by the time between measurements gives a measure of the short-term (between feeds) rate of milk synthesis.

Chart: Calculation of the rate of milk synthesis
Calculation of the rate of milk synthesis. The solid red lines represent the change in breast volume with breastfeeding, and the dashed blue line represents the change in breast volume with the synthesis of milk. The rate of milk synthesis was calculated as the change in breast volume over time.

SHORT-TERM RATE OF MILK SYNTHESIS

Using the CBM system we have focused on identifying the factors regulating the short-term (i.e. between breastfeeds) rate of milk synthesis. Popular theory suggests that milk synthesis is controlled through prolactin. The rationale for this was that the prolactin levels in the maternal plasma increase in response to suckling (Noel et al., 1974). Thus, it was envisaged that the elevated prolactin levels would stimulate the synthesis of enough milk to replace the removed milk. Although this theory has not been tested, it has become entrenched in the text-books (e.g. Dulbecco, 1987). We used the CBM system to measure the in vivo rate of milk synthesis and to investigate its relationship with prolactin. We measured the concentration of prolactin in the plasma before and 45 minutes after the commencement of breastfeeds over the first six months of lactation. Both the basal and the peak concentrations of prolactin in the plasma declined over this period. In contrast, neither 24 h milk production nor the average short-term rates of milk synthesis changed significantly over this period. Thus, the concentration of prolactin in the plasma was not related to the rate of milk synthesis (Cox et al., 1996). In addition, it was concluded that the control of milk synthesis was located within each breast, since the rate of milk synthesis in one breast was not related to the rate of milk synthesis in the other breast.

Chart: The variation in the rate of milk synthesis
(Cox et al., 1996) The variation in the rate of milk synthesis, both within and between the breasts, of an individual mother over a single day.

Daly et al. (1993b) used the CBM system to measure the changes in breast volume of seven breastfeeding mothers over each breastfeed during a 24 h period. From these measurements they could determine the maximum and minimum volume of the breast over the 24 h period, the storage capacity of each breast (maximum-minimum breast volume), the degree of emptying of the breast, before and after each breastfeed, and the short-term rates of milk synthesis. They found that the storage capacity of the breasts ranged from 80 to 600 mL. The breast was not necessarily completely emptied at each breastfeed (Mother A; Figure 8), indicating that the infants regulated their milk intake presumably according to their appetite. Daly et al. (1993b) suggested that the storage capacity of the breast influenced the frequency of breastfeeding. Compared to mother A, mother B had a much smaller storage capacity and her infant nursed more frequently. By more frequent breastfeeding this infant was able to obtain at least as much milk as the infant of mother A (956 vs 896 mL/24 h, respectively).

degrees of fullness
The degree of fullness (1-degree of emptying (Cox et al., 1996)) of the left breast from before to the end of a breastfeed and the rate of milk synthesis in that breast for two of the women described by Daly et al. (1993b). Note that there is an inverse relationship between these two factors in the case of mother A, while for mother B both the rate of milk synthesis and the minimum degree of fullness after each breastfeed are relatively constant.

The rate of milk synthesis varied from breastfeed to breastfeed (Figs. 8and 9). Taking the example of mother A, the rate of milk synthesis was lowest when the breasts were full and highest when they were near empty. In the case of mother B there was no major variation in the rate of milk synthesis throughout the day. Overall, Daly et al. (1993b) found that the rate of milk synthesis was related to the degree of emptying of the breast and concluded that the control of the rate of milk synthesis was localised within the breast. Furthermore, this control responded to changes in the degree of breast fullness (Daly et al., 1993b; Cox et al., 1996). The short-term rates of synthesis for mother B’s right breast are consistent with this conclusion as it was emptied to a constant degree (Figure 9).

Since prolactin is a potent stimulator of the synthesis of milk components (Cowie et al., 1980), and the control of milk synthesis is localised within the breast (Daly et al., 1993b; Cox et al., 1996), we hypothesized that the control of milk synthesis may be related to a restriction on the binding and subsequent entry of prolactin into the mammary gland. Noilin (1979) found that the entry of prolactin into lactating rat lactocytes was restricted by the morphology of the lactating cell, that is, prolactin entered the cells only when they were tall and columnar and had minimal milk in the alveolus. We found that the amount of prolactin in the milk from a full gland was high at first and then declined as milk was removed from the breast. This is consistent with Noilin (1979) assuming that there is minimal mixing of milk within the breast, and that the fore-milk is synthesized during the periods when the lactocytes are in the columnar formation and the alveolus is close to empty (Cox et al., 1996).

MILK FAT

For many years it has been known that the fat content of milk that is expressed from the breast following a breastfeed (hind-milk) is higher than in the milk before a breastfeed (fore-milk). This has lead to the suggestion that, in cases of lactation insufficiency, women should feed their infants more "hind-milk", assuming that this milk has a higher energy content. Daly et al. (1993a) measured the fat content of the milk, before and after every breastfeed for 24 h and found that rather than being related to whether it was fore- or hind-milk, the fat content was related to the degree of fullness of the breast. Therefore, as the breast is progressively emptied, the fat content in the milk increases.

PRINCIPAL FINDINGS

  1. The concentration of prolactin in the maternal plasma does not control milk synthesis.
  2. Infants can regulate their own milk intake.
  3. The rate of milk synthesis is regulated within each breast.
  4. The rate of milk synthesis is related to the degree of emptying of the breast.
  5. The capacity of each breast to store milk varies greatly between women.
  6. Storage capacity of the breasts can influence the flexibility a mothers has in relation to the frequency of breastfeeding her infant.
  7. The control of milk synthesis may restrict the binding and entry of prolactin into the cell.
  8. The fat content of the milk progressively increased as the breast was emptied, thus the fat content of milk was related to the fullness of the breast.

REFERENCES

Alexander, B. F., and Ng, K. C., 1987, "3-D Shape measurement by active triangulation using an array of coded light stripes", SPIE, Optics, Illumination and Image Processing for Machine Vision II, 850:199-209.

Arthur, P. G., Jones, T. R., Spruce, J., and Hartmann, P. E., 1989, "Measuring short-term rates of milk synthesis in breast-feeding mothers", Quarterly Journal of Experimental Physiology, 74:419-428.

Cox, D. B., Kent, J. C., Owens, R. A. and Hartmann, P. E., 1994, "Mammary morphological and functional changes during pregnancy in women", Proceedings of the Australian Society for Reproductive Biology, 26:47.

Cox, D. B., Owens, R. A., and Hartmann, P. E., 1996, "Blood and milk prolactin and the rate of milk synthesis in women", Experimental Physiology, 81:1007-1020.

Cowie, A. T., Forsyth, I. A., and Hart, I. C., 1980, "Hormonal Control of Lactation", (Springer-Verlag; Berlin).

Daly, S. E. J., Di Rosso, A., Owens, R. A., and Hartmann, P. E., 1993a, "Degree of breast emptying explains changes in the fat content, but not fatty acid composition, of human milk", Experimental Physiology, 78:741-755.

Daly, S. E. J., and Hartmann, P. E., 1995, "Infant demand and milk supply. Part 2: The short-term control of milk synthesis in lactating women", Journal of Human Lactation, 11:27-37.

Daly, S. E. J., Kent, J. C., Huynh, D. Q., Owens, R. A., Alexander, B. F., Ng, K. C., and Hartmann, P.E., 1992, "The determination of short-term breast volume changes and the rate of synthesis of human milk using computerized breast measurement", Experimental Physiology, 77:79-87.

Daly, S. E. J., Owens, R. A., and Hartmann, P. E., 1993b, "The short-term synthesis and infant-regulated removal of milk in lactating women", Experimental Physiology, 78:209-220.

Dulbecco, R., 1987, "The Design of Life", (Yale University Press; New Haven) p. 161.

Huynh, D. Q., Owens, R. A., Daly, S. E. J., Kent, J. C., and Hartmann, P. E., 1990, "The rapid estimation of short term changes in breast volume", Proceedings of the 6th International Conference on Biomedical Engineering, Singapore, 93-96.

Noel, G. L., Suh, H. K., and Frantz, A. G., 1974, "Prolactin release during nursing and breast stimulation in post partum and non-post partum subjects", Journal of Clinical Endocrinology and Metabolism, 38; 413-423.

Noilin, J. M., 1979, "The prolactin incorporation cycle of the milk secretory cycle", Journal of Histochemistry and Cytochemistry, 27:1203-1204.

This information has been contributed by

David B. Cox, Robyn Owens and Peter Hartmann 
Department of Biochemistry 
University of Western Australia 
Nedlands, Perth 
W.A. 6907 Perth, Australia

phone: +61 9 380 2303 
fax : +61 9 380 1148

For additional information contact David Cox (e-mail:This email address is being protected from spambots. You need JavaScript enabled to view it. )

last update: June 1998

Breast-feeding: Perseverance brings results

Reproduced from www.oregonlive.com 
10/06/02 
PATRICK O'NEILL - THE OREGONIAN

It’s not news that mother’s milk is the best for baby, but that is certainly the reason new moms give for their decision to breast-feed.

Few speak about the new research that has shown that breast-feeding can protect against a wide variety of cancers as well as osteoporosis, infections, obesity and even depression.

No one mentions the landmark study published in July in The Lancet medical journal that found that the more children a woman has and the longer she nurses them, the less chance she has of developing breast cancer.

Women simply answer in chorus: It’s the best thing for my baby.

More and more, research shows it’s good for mom, too.

Despite all this good news, nursing doesn't necessarily come easily to everyone. Problems with Starting Out Right, producing enough milk and feeling comfortable are common physical concerns. At times, career demands and social stigmas play against nursing, leaving new moms to abandon their desires and this good news altogether.

Success, experts say, starts with early commitment -- which means you need to start thinking about it even before you become pregnant.

"The commitment to breast-feeding occurs before pregnancy," says Margi Munson, an international board-certified lactation consultant and coordinator of lactation services for Legacy Health System. "The more you are really planning on breast-feeding, the more likely you are to succeed."

She has found that women who say they're going to "try" to breast-feed are the least likely to succeed because they seem to lack a positive attitude.

"So much of breast-feeding is psychological anyway," she says. "Breast-feeding is 90 percent in your brain and the other 10 percent is on your chest."

Munson says 85 percent to 90 percent of new mothers in the Legacy system start breast-feeding in the hospital.

Figures on breast-feeding are sketchy, but Munson guesses that 30 percent to 60 percent of Legacy mothers are still breast-feeding their infants six months later.

A 1998 survey by Abbott Laboratories found that 64 percent of women nationwide begin breast-feeding. The national figure tapered off to 29 percent by six months and 16 percent by one year, the length of time the American Academy of Pediatrics recommends that mothers breast-feed.

"We feel like we struggle keeping women on track," Munson says, adding that breast-feeding is far more popular with women on the West Coast than in the East.

A learned skill At Legacy hospitals moms and babies are encouraged to breast-feed within the first hour of life, something Jennifer Merrill had planned to do when Sophie was born. Sophie, however, had other thoughts, leaving new mom and little daughter in a frustrated state for a couple of weeks.

Merrill, a recent graduate from Oregon Health & Science University, knew the benefits of breast milk and was discouraged when Sophie didn't immediately nurse.

"It was hard at the beginning," Merrill, 32, says. "I was scared." Sophie wasn't eating enough and lost weight, so Merrill sought out advice from Legacy. The "incredibly helpful" advice she received put her and Sophie back on track. "A lot of people say, 'Oh, you'll know, the baby will know' how to nurse, and we didn't," says Merrill, who remembers wondering why as a mother and a nurse she couldn't make it work. "If I didn't have the help (of the lactation services), the pediatrician would have put her on formula. With Margi’s support, I was able to say this is what I’m going to do," says Merrill, who lives with husband Anthony in Southeast Portland. "As long as we saw increments in her weight gain, I was encouraged to keep going."

Third time’s a charm Shannon Kirk’s desire to get breast milk to her first baby met with different hurdles. Colin, who is now 5, was born prematurely at 32 weeks.

Colin was not strong enough to eat on his own and was in the neonatal intensive care unit at Legacy Emanuel Hospital & Health Center for three weeks. During that time Kirk, 34, pumped her milk for Colin until he learned to latch on and nurse on his own.

When her daughter came along two years later, also prematurely, at 31 weeks, Kirk maintained her desire to nurse, but little Caitlin was born with pneumonia, and her lungs were not developed. "I pumped for two straight months," Kirk says, adding that Munson was her biggest supporter.

No one had told Kirk that it was uncommon for preemies to latch on to nursing, and it took Caitlin a long time to get it. "It was devastating for me," Kirk says. "It was something I wanted to do so badly. . . . It’s important for them to have my milk." Kirk says she and Caitlin "muddled through," and two weeks past her full-term date, "Caitlin got it."

The support Kirk, who lives in Happy Valley with her husband, Troy, received from Munson is the kind that’s vital to successful nursing for many new moms.

Kirk was thrilled with the immediate bond she had with her third child, Ryan. Although Kirk spent 13 weeks on bed rest, it paid off when she carried Ryan to term and was able to hold him and nurse him nearly immediately. "Nursing is an amazing relationship with your child," Kirk says.

Kirk, who isn't working outside the home now, did return to work after the birth of her first child, Colin, and is passionate about employers making it easy for women to continue to nurse.

"It’s the best thing for the baby," Kirk says

Balancing nursing, work Merrill, who returns to work in February, hopes to continue nursing Sophie for a year. "I'll be working in a hospital, which is supportive of breast-feeding."

The best way to tune in your commitment is to surround yourself with friends and relatives who support your decision to breast-feed.

"Any mom who has an opportunity to breast-feed at work or at day care is going to have a higher rate of success -- whatever their goal," Munson says.

Lee Wyatt’s goal was to get her milk to her daughter.

Wyatt’s third child, Gehrig, was born 10 months ago with an undiagnosed neuromuscular condition. "There is some disconnect in her brain from what her brain wants to do and what her body is able to do," says Wyatt, an attorney who lives with her husband, Pete Baur, daughter Gretel, 5, and son Gustav, 2 1/2, in Corbett. Gehrig is unable to take food by mouth, so Wyatt pumped her "Mom’s milk," as she calls it, and fed it to Gehrig through a gastrointestinal tube. "Mom’s milk is brain food," Wyatt, 37, says.

Gehrig is showing improvements in both motor and brain function, something "we had no hope for" when Wyatt left the hospital after Gehrig’s birth. "Where she is today is part miracle, part mother’s milk and part physical therapy," Wyatt says.

Moms benefit from nursing Breast-feeding may also be "brain food" for the mom, according to Dr. Elizabeth Mezzacappa, assistant clinical professor of medical psychology in psychiatry at Columbia University College of Physicians & Surgeons and a breast-feeding researcher.

Mezzacappa says there’s a deep connection between breast-feeding and activity in the brain, which helps explain why nursing women suffer less depression than their bottle-feeding counterparts.

"My analysis of data indicated that women who breast-fed were half as likely to have a high depression score shortly after the baby’s birth than mothers who bottle-feed," she says.

Research shows that cells in the brains of rats actually change their structure when the animals begin lactating. The cells in question, called oxytocin neurons, are in areas of the brain that control emotions. Researchers are only beginning to understand the depth of the connection between the brain and the act of breast-feeding. That connection is an evolutionary certainty, Mezzacappa says, because feeding infant mammals is essential to their survival.

Carol Houtari, manager of La Leche League’s Center for Breast-Feeding Information, says medical schools don't stress the importance of breast-feeding. As a result, doctors don't give their patients enough guidance in that area.

"Women need to understand from their obstetricians how important breast-feeding is," she says.

That information is essential to overcoming the embarrassment some women feel about nursing in public. "In our country breasts are considered to be sexual objects," she says. "Even if women use a pump at work, they're embarrassed because people hear the pump."

Kirk finds nothing to be embarrassed about.

"I’ve been to two home Ducks games with 57,000 fans," Kirk says about nursing in public. "I don't care. This is what we do. It’s so healthy." 

Patrick O'Neill; 503-221-8233; 
This email address is being protected from spambots. You need JavaScript enabled to view it.

Natural but not necessarily easy

Reproduced from Burlington Free Press 
Published: Monday, August 1, 2005 
By Susan Green - Correspondent

Sonya Sapir, Vickie Durgin and Topaz Weis are nothing if not determined.

The three mothers range in age from 29 to 24 to 43, respectively, and live in different towns: Williston, Monkton and Burlington. They don't know each other, but share a common belief that breastfeeding is ideal for all babies.

This credo does not necessarily mean that Sapir, Durgin and Weis have had an easy time of it. Despite varying degrees of difficulty, however, they remain undeterred when it comes to nursing their children:

"It just makes sense," Sapir says of breastfeeding her 8-week-old son, Colden.

"I like looking into my babies' eyes while they nurse," acknowledges Durgin, the mother of toddler Hunter and his brother Hayden, who turns 1 this week. "At the end of a hectic day, it’s a way of saying, ’mommy loves you.'"

"I want the absolute best for my daughter," says Weis, who adopted 3-month-old Kiki in mid-May.

World Breastfeeding Week, Aug. 1-7, is a time for parents and health professionals to celebrate the advantages of drinking mother’s milk.

"Most pediatricians recognize the nutritional, immunological, social, economic and developmental benefits of nursing," observes Dr. Lewis First, chief of pediatrics for Vermont Children’s Hospital at Fletcher Allen Health Care. "The best thing a mom and dad can do is breastfeed their baby for as long as possible."

Sometimes it appears to be easier said than done. While many newborns take to the breast without a hitch, periodically, challenges emerge even for mothers who are totally dedicated to the idea of breastfeeding.

Dr. Eliot Nelson of University Pediatrics in Williston has found that it’s a delicate balance. "I encourage moms to keep going, but recognize that some may feel anxious or uncertain about breastfeeding," he says. "I try to not to make them feel bad about that decision. Formula is a good alternative these days if nursing is out of the question."

Some pediatricians, like Dr. Pat Colander of Middlebury, are wary of formula and of the vast influence that formula companies have on the medical establishment. When she’s not available, "I dread that my patients who are breastfeeding moms might see other physicians in this area who happen to be on call." In her view, "some babies are naturals (at nursing); for others, it can take a little getting used to."

Colander’s own life reflects that equation. "After giving birth in 1973, I had a breast infection called mastitis," says Colander, "but I turned to the La Leche League, and they got me through it. I was able to nurse my firstborn for 5 1/2 years."

She went on to have four more children, all instant breastfeeding success stories. Colander’s initial hardships are similar to those encountered by Sonya Safir, who nursed Colden smoothly in the hospital but hit a roadblock during her first weekend at home. "My milk came in quickly and the latch got more painful," she says, referring to the way a baby connects with the nipple. "Although he was gaining weight, I wasn't comfortable because I had a blister."

Once Safir applied a medicated cream to her nipple and "got the latch right" about seven weeks ago, Colden’s feedings no longer hurt.

By contrast, Vickie Durgin has been to hell and back twice. Hunter was delivered in 2001 via Caesarean section, which required antibiotics that are known to sometimes cause complications when she started breastfeeding.

"A visiting nurse said he was latching correctly, but I was so sore I would clench my teeth and dig my nails into a pillow," Durgin recalls. "I was at war with myself. Even though the pain was intolerable, I didn't want to stop nursing."

She had a clogged milk duct, both nipples were bleeding, and an ensuing infection emitted green pus. The agony continued for almost three months. "Eventually, I had only two choices: Quit nursing and have surgery to cut open the abscess or figure out how to latch properly," Durgin says. "I’m stubborn, so I chose to continue and was able to breastfeed Hunter for 22 months."

But her ordeal resumed when Hayden was born -- also by C-section -- a year ago. Durgin’s nipple cracked around the edge. A doctor wanted to use stitches that once again would have interfered with breastfeeding.Instead, Durgin’s general practitioner repaired the tear with a medicated substance "like Superglue" said Dr. Jack Newman, a renowned Canadian breastfeeding expert who was in St. Albans to conduct a workshop. She has had no subsequent problems.

For Topaz Weis, the issue has been producing milk against all odds. Even after losing her biological baby while 16 weeks pregnant in January, she began lactating.

"We were already in the process of trying to adopt. I decided to use a breast pump so I’d have all that good stuff, like colostrum," Weis says of the antibody-rich secretion in mother’s milk during the first week. She intended to be ready for any infant that might come into her life.

Weis stopped pumping at the end of February. On May 11, she and her husband received a call from the adoption agency about a 10-day-old baby in Philadelphia that was theirs if they could head for Pennsylvania almost immediately.

"We packed all that breast milk in dry ice," Weis says, "but what took me eight months to pump took Kiki about five days to drink."

The couple quickly embarked on a multifaceted approach. "I’m in the process of re-lactating," Weis explains. "I take herbs like fenugreek, blessed thistle and chasteberry tincture, as well as a drug called domperidone that helps me produce more of my own milk."

The domperidone was prescribed by her primary-care physician, who is kept abreast of what Weis calls the "established protocol of herbal supplements" that she follows.

Kiki’s intake is supplemented by lactating women from across the country who contribute their excess to a "human milk bank" in North Carolina. A week’s supply of frozen milk, which has been thoroughly tested and pasteurized, is FedExed overnight to its Vermont destination. The baby later drinks it through a thin tube placed next to her mother’s nipple, which delivers some authentic Weis milk at the same time.

The downside of this arrangement is primarily expense -- $500 per week, which her insurance company declines to cover. She’s now in touch with three local women who are breastfeeding their children and willing to donate extra milk at no cost, until Weis is able to become the sole wellspring for her daughter.

Meanwhile, she is reveling in motherhood. "Kiki’s such a nice, sweet, good-natured girl, and she sure loves the booby juice," Weis quips.

The "booby juice" has been Kathleen Bruce’s mission in life as a Williston mother of three who became a La Leche League leader in 1988 and an international board-certified lactation consultant in 1993. She helped Safir, Durgin and Weis through their darkest days. They all sing her praises.

"I plan to have more breastfed babies," vows Durgin, whose optimism sounds like a profile in courage. "And I hope Kathleen can be with me in the delivery room."

As a pediatric nurse who once worked with premature infants at Fletcher Allen, Bruce is not stranger to the hospital setting.

"Breastfeeding is a behavior that requires support," she contends. "If a mother is uncomfortable when feeding, she doesn't have to suffer through it. We can always find a solution."

"We" includes her two partners in Lactation Resources of Vermont, a private practice that offers home visits to nursing mothers in Chittenden, Franklin, Grand Isle, Addison and Washington counties.

Bruce is also the online nurse-lactation consultant for Medela, a breast pump manufacturer based in Switzerland and Chicago. "I answer more than 900 questions about breastfeeding a month that are e-mailed from all over the world," she notes.

Her philosophy about nursing, no matter the hurdles, is unequivocal: "Our bodies are able to build a baby and feed a baby. The human race has survived because breastfeeding works, or we wouldn't be here on this planet."

Dr. Eliot Nelson is a bit less adamant. "More than 50 percent of new moms in my practice start breastfeeding," he says. "Others come to it with a less firm commitment: 'I'll at least give this a shot.'"

His colleague, Dr. Lewis First, has a more of an advocacy perspective. "There are so many things you can try before you even think about giving up," he points out. "I’m not here to condemn formula, but immunity protection and health benefits come with nursing. Breastfeeding is the No. 1 choice for babies."

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