IgG4 in human colostrum and human milk: continued local production or selective transport from serum

Colostrum, mature milk, and paired plasma samples were obtained from 10 postpartum women who had not been previously studied. The geometric mean concentration of IgG4 in colostrum (3.3 micrograms/ml) was similar to the mean concentration in mature milk (3.0 micrograms/ml). The arithmetic mean for the percent of IgG = IgG4 was 10.3 +/- 3.3% for colostrum, 10.3 +/- 3.1% for mature milk, 2.6 +/- 0.3% for early plasma, and 1.7 +/- 0.3% for later plasma. Local mammary production of immunoglobulin was determined by subtracting the estimated serum contribution from the measured concentration in colostrum or milk. Evidence for local mammary production of IgG4 was found in 5 of 10 colostrum samples and 8 of 10 mature milk samples. These observations indicate that the previously observed selective enrichment of IgG4 in colostrum is also true for mature milk. These are the first studies suggesting continued local production of any immunoglobulin other than IgA in mature human breast milk.     

A SUGGESTED ROLE FOR PRECOLOSTRUM IN PRETERM AND SICK NEWBORN INFANTS

ABSTRACT. Samples of precolostrum (colostrum gravidarum), colostrum and mature milk obtained from five women during their antenatal and postnatal periods were measured for IgA, IgG, IgM, alpha-1-antitrypsin, lactoferrin, lysozyme, B, A globulin (C3) and B, E globulin (C4) by single radial immunodiffusion. Protein concentrations in precolostrum were equal to or greater than those found in colostrum obtained during the first 12-48 hours following delivery. Secretion of precolostrum is common, occurs early in the antenatal period and may often be of considerable volume. The anti-microbial proteins contained within this milk can be preserved intact by freezing. This represents an untapped pool of bacteriostatic proteins with specific activity against neonatal pathogens. We suggest that a potential protective effect against serious infection may be obtained by administering precolostrum to "at risk" infants during the first few days of life.     

IgG4 in Human Colostrum and Human Milk: Continued Local Production or Selective Transport from Serum

ABSTRACT. Colostrum, mature milk, and paired plasma samples were obtained from 10 postpartum women who had not been previously studied. The geometric mean concentration of IgG4 in colostrum (3.3 μg/ml) was similar to the mean concentration in mature milk (3.0 μg/ml). The arithmetic mean for the percent of IgG = IgG4 was 10.3±3.3% for colostrum, 10.3±3.1% for mature milk, 2.6±0.3% for early plasma, and 1.7±0.3% for later plasma. Local mammary production of immunoglobulin was determined by subtracting the estimated serum contribution from the measured concentration in colostrum or milk. Evidence for local mammary production of IgG4 was found in 5 of 10 colostrum samples and 8 of 10 mature milk samples. These observations indicate that the previously observed selective enrichment of IgG4 in colostrum is also true for mature milk. These are the first studies suggesting continued local production of any immunoglobulin other than IgA in mature human breast milk.     

Concentrations of Fe, K, Na, Ca, P, Zn and Mg in maternal colostrum and mature milk

The objective of this study was to determine the concentrations of Fe, K, Na, Ca, P, Zn and Mg in colostrum and mature milk (2 months) from nursing mothers, and the correlation between the concentration of these micronutrients and newborn weight, maternal age, gestational age GA, inter-pregnancy interval, and gestational weight gain. Thirty one women donated milk on the 2nd postpartum day and on the 2nd month of lactation. Micronutrients were analysed by atomic emission spectrophotometry. The concentrations (mean+/-SD) of Fe (0.12+/-0.08; 0.09+/-0.5 mg/100 ml), Zn (0.93+/-0.36; 0.15+/-0.06 mg/100 ml), K (62.8+/-11.5; 46.2+/-0.84 mg/100 ml) and Na (33.3+/-12.3; 20.5+/-15.6 mg/100 ml) decreased from colostrum to mature milk, whereas Ca (21.4+/-5.8; 25.0+/-3.1 mg/100 ml) and P (11.12+/-2.8; 13.7+/-2.0 mg/100 ml) increased. Correlations were observed between Zn and Ca concentrations and GA (r=-0.41, p=0.042; r=0.48, p=0.014, respectively), between Ca and K and inter-pregnancy interval (r=0.56, p=0.001; r=0.38, p=0.033, respectively), and between Mg and P and maternal age (r=0.49, p=0.005; r=0.37, p=0.042, respectively). The Zn concentration in colostrum showed a negative correlation with gestational weight gain (r=-0.49, p=0.006), and Na concentration showed a negative correlation with newborn weight (r=-0.38, p=0.036). The concentration of micronutrients in colostrum and mature milk (2 months) suffers alterations, including a decrease in Fe, Zn, K and Na and an increase in Ca and P, probably in order to satisfy the requirements of the nursing infant. Micronutrients are influenced by birth weight, maternal age, gestational weight gain, GA and inter-pregnancy interval.     

Beta endorphin concentrations in human milk

BACKGROUND: The source and regulatory mechanisms that elevate beta-endorphin (beta-EP) approximately twofold higher than circulating plasma levels in the colostrum of lactating mothers are still unknown, and no studies have examined beta-EP availability previously during maturation phases of human milk. Therefore, the aim of this study was to determine whether concentrations of beta-EP vary over time between colostrum, transitional, and mature breast-milk and to evaluate whether this depends on the method of delivery. METHODS: Mothers of healthy full-term and pre-term newborn infants who planned to breast-feed their newborn infants were considered for this study. They were consecutively recruited in one of 3 groups of 14, according to delivery method: group 1, vaginal delivery at term (gestational age 40.2 +/- 0.3 weeks; birth weight, 3.48 +/- 0.09 kg); group 2, preterm vaginal delivery (gestational age, 35.6 +/- 0.3 weeks; birth weight, 2.49 +/- 0.08 kg); and group 3, at-term elective cesarean section (gestational age, 39.0 +/- 0.3 weeks; birth weight, 3.32 +/- 0.14 kg). Three consecutive breast milk samples were obtained on the fourth day after birth, before each mother's discharge, and thereafter on the 10th and 30th postpartum days, close to expression of the colostrum, transitional, and mature milk production phases, respectively, to test beta-EP concentrations (beta-Endorphin 125I RIA; INCSTAR Corporation, Stillwater, MN). Data are presented as mean +/- standard deviation. Statistical comparison of beta-EP concentration among the three lactating mother groups was performed using the Kruskal-Wallis nonparametric test. In addition, to test the hypothesis of a trend toward smaller values with time of beta-EP, the authors computed within each mother group a P value per trend (Kruskal-Wallis test) of beta-EP concentration averages on the 4th, 10th, and 30th days, respectively. Student's t test for independent samples was used for the analysis of the other data. The 0.05 significance level was used in the statistical analysis. All computations were made by computer. RESULTS: Colostrum beta-EP concentrations on the fourth postpartum day of group 1 and group 2 mothers who were delivered of a neonate vaginally, at term, or prematurely were significantly higher (P < 0.01) than colostrum levels of group 3 mothers who underwent cesarean section. Group 2 mothers who were delivered of a neonate vaginally and prematurely presented the highest beta-EP concentrations (P < 0.05), lasting until the transitional milk phase (10th day). No significant differences were found across all 3 groups of lactating mothers in mature milk (30th day) beta-EP concentrations. In addition, the beta-EP trend toward smaller values with time within each of the three groups on days 4, 10, and 30 was statistically significant (P < 0.01 per trend). CONCLUSIONS: It is hypothesized that elevated beta-EP concentrations in colostrum and transitional milk of mothers who were vaginally delivered of infants may contribute to postnatal fetal adaptation, to overcoming birth stress of natural labor and delivery, and at the same time to the postnatal development of several related biologic functions of breast-fed infants.     

Interleukin-12 in human milk.

The presence of interleukin-12 (IL-12) in 39 samples of human milk was investigated using the enzyme-linked immunosorbent assay. IL-12 (>40 pg/mL) was detected in 24 of the 39 samples collected (1408 +/- 2256 pg/mL, mean +/- SD, n = 24). A range of concentrations of IL-12 was observed in colostrum, transitional, and mature milk, with an apparent decrease in the mean concentration over time postpartum.     

Lower energy content of human milk than calculated using conversion factors

BACKGROUND: Bodyweight gain of formula-fed babies is usually higher than that of breast-fed ones. The energy content of human milk is usually quantified not by direct measurement but by calculation based on The Standard Tables of Food Composition in Japan. For this study, the energy of human milk was quantified in two ways, using a direct measurement and a calculation method. METHODS: A total of 227 milk samples (192 colostrum, 21 transitional milk, and 14 mature milk) were collected from 114 healthy women. Energy of the whole milk was measured by ballistic bomb calorimetry. The content of protein, fat, and carbohydrate was determined by direct measurement methods. Energy of the milk was also calculated according to the indices in The Standard Tables. RESULTS: The mean value for all milk samples of directly measured energy was significantly lower than that of the calculated energy (58.1 +/- 8.1 vs. 64.5 +/- 10.6 kcal/100 g, n = 227, P < 0.05). Similar results were observed in colostrum and transitional milk but not in mature milk. Measured energy in mature milk was significantly higher than that in colostrum (64.2 +/- 3.6 vs. 57.1 +/- 8.0 kcal/100 g, P < 0.05). Protein concentration in mature milk was significantly lower than that in colostrum (1.4 +/- 0.4 vs. 2.2 +/- 0.7 g/100 g, P < 0.05). CONCLUSIONS: The measured energy content of human milk was lower than the calculated energy based upon the Standard Tables, suggesting that formula milk contains excessive energy.     

Sequential changes in the antimicrobial protein concentrations in human milk during lactation and its relevance to banked human milk

The concentrations of eight antimicrobial proteins, 11S IgA, IgG, IgM, alpha 1-antitrypsin, lactoferrin, lysozyme, C3, and C4 were measured in sequential samples of colostrum, transitional and mature milk from 47 women in Merseyside, England by single radial immunodiffusion. Concentrations were highest in colostrum and then declined until relatively stable concentrations were reached in mature milk. A wide variation in protein concentrations was noted in the milk from different individuals at any given postpartum time interval and this was particularly so during the first 4 days postpartum. The decline in individual antimicrobial protein concentrations seen in samples of transitional milk appeared to take a variable period of time to stabilize to mature milk concentrations of each protein. These variations may reflect different rates of transport or secretion of these proteins from the alveolar epithelial cells into the alveolar lumen. Because of the wide variations in antimicrobial proteins observed in milk samples from the individuals in this study at similar postpartum time intervals, it is suggested that banked milk should be monitored not only for bacterial contamination, but also for levels of antimicrobial proteins, if it is considered that a major advantage of unprocessed human milk is the immune protection which it confers.     

Lipid composition of prepartum human mammary secretion and postpartum milk

Changes in lipid composition of mammary secretions of five women were studied at two prepartum periods and compared with composition of colostrum, transitional, and mature human milk. Fat content was approximately 1 g/dl during early (-42.0 days before parturition) and late (-9.5 days) prepartum periods and increased to 3-4 g/dl in colostrum (3.0 days post partum), transitional (7.2 days), and mature milk (56.2 days). Most of the lipid present was triglyceride either pre- (93%) or post- (97%) partum. All fat globule core lipids, with the exception of 1,3-diglycerides, increased from prepartum concentrations to levels usually found in milk. Prepartum secretions contained higher amounts of the membrane components, phospholipid (3.2 g/dl), cholesterol (2.3 g/dl), and cholesteryl ester (1.1 g/dl), which declined postpartum to 0.65, 0.37, and 0.09 g/dl, respectively. Thus, the content of core lipids exhibited an opposite pattern to the content of membrane lipids pre- and postpartum. With regard to synthesis of fatty acids, prepartum secretory mechanisms appeared to be very similar to those occurring postpartum since fatty acid composition of prepartum secretions closely resembled that of postpartum milk.     

A longitudinal study of human milk composition in the second year postpartum: implications for human milk banking

While the composition of human milk has been studied extensively in the first year of lactation, there is a paucity of data regarding human milk composition beyond one year postpartum. Policies vary at milk banks around the world regarding how long lactating women are eligible to donate their milk. The primary purpose of this study is to describe longitudinal changes in human milk composition in the second year postpartum to support the development of evidence based guidelines regarding how long lactating women can donate human milk to a milk bank. Nineteen lactating women in North Carolina provided monthly milk samples from 11 months to 17 months postpartum (N = 131), and two non‐profit milk banks provided (N = 33) pooled, unpasteurized milk samples from 51 approved donors less than one year postpartum. There was a significant increase (P < 0.05) in the concentration of total protein, lactoferrin, lysozyme, Immunoglobulin A, oligosaccharides and sodium in longitudinal samples of mother's milk between 11 and 17 months postpartum, while zinc and calcium concentrations declined, and no changes were observed in lactose, fat, iron and potassium. Human milk in the second year postpartum contained significantly higher concentrations of total protein, lactoferrin, lysozyme and Immunoglobulin A, than milk bank samples, and significantly lower concentrations of zinc, calcium, iron and oligosaccharides. Accepting milk bank donations beyond one year postpartum is a potential strategy for increasing the supply of donor milk, but may require mineral fortification.     

Total lipid content and fatty acid composition of preterm human milk

The total lipid content and fatty acid composition of preterm human colostrum and milk were analyzed from aliquots of 24-h collections of colostrum, transitional milk, and mature milk obtained from 21 women who had delivered premature infants with a mean birth weight of 1,049 +/- 38 g (mean +/- SEM) and a mean gestational age of 29 +/- 0.4 weeks. The total lipid content increased significantly with time of lactation (p less than 0.001), from 1.99 +/- 0.25 g/dl in colostrum to 3.89 +/- 0.28 g/dl in mature milk. With respect to the fatty acid pattern, the percentages of 12:0 and 14:0 increased significantly (p less than 0.001), while those of 16:0 (p less than 0.05) and 18:1 (p less than 0.001) decreased significantly with time of lactation. The percentages of 10:0, 16:1, 18:0, 18:2, and 18:3 did not vary significantly with the duration of lactation. Similar compositional changes have been described in term human colostrum and milk as the duration of lactation progresses.     

Atrial natriuretic peptide and endothelin concentrations in human milk during postpartum lactation

Abstract Milk samples from lactating women ( n = 24) were examined for atrial natriuretic peptide (ANP) and endothelin-1 (ET-1) content throughout the first 3 months postpartum. Samples were collected at the beginning (foremilk) and towards the end (hindmilk) of nursing. ANP was detected in the milk samples. A value of 9.4 ±1.8 pmol/1 (mean ± SEM) was observed on the third day postpartum. No significant variations in concentrations were observed during the 3 months examined. Foremilk and hindmilk ANP concentrations were also similar. ET-1, as previously reported, is present in the milk of lactating women. According to our observations, the concentration of ET-1 varies during the first 3 postpartum months. The highest concentrations were observed on the third day (10.2 ± 1.8 pmol/1) of lactation, decreasing to 4.5 ± 0.8 pmol/1 after 1 week ( p < 0.05) and to 2.0 ± 0.3 pmol/1, at 1 month postpartum ( p < 0.05), this level being maintained for up to 3 months postpartum. Foremilk samples on the third day postpartum contained significantly higher concentrations of ET-1, compared to hindmilk samples (10.2 ± 1.8 vs 7.7 ± 1.2 pmol/1, p < 0.05). The stable levels of ANP and the initial high and subsequently decreasing levels of ET-1 in human milk, during the first 3 months postpartum, suggest that these peptides might be of importance either in the lactating mammary gland or in the suckling newborn.     

Intestinal absorption of IgA in the newborn

The aim of this study was to establish whether or not the newborn can absorb IgA from colostrum, using two feeding regimens. Single radial immunodiffusion on commercial Behring plates was used for IgA quantitation. In group A, 30 mature newborn infants born by vaginal delivery and fully breast fed, cord serum IgA concentration was 0.0990 +/- 0.0294 mg/ml (means +/- SEM). IgA was detectable in 9 of 30 infants. On the 3rd day of life, IgA concentration in serum was 0.3610 +/- 0.0194 mg/ml (means +/- SEM). It was detectable in all 30 infants; on the 5th day of life, its concentration was 0.4293 +/- 0.0365 mg/ml (means +/- SEM). In group B, 39 newborn infants born by cesarean section and fed boiled human milk exclusively, IgA was not detected either in cord, or in venous blood on the 3rd and 5th day of life. The rise of serum IgA in breast-fed newborn infants, highly significant from the 1st to the 3rd day of life (p less than 0.0001), and its increase between the 3rd and 5th day, although not significant, was in distinct contrast to the undetectable serum IgA in newborn infants fed boiled human milk. These data strongly suggest that IgA absorption from colostrum occurs at least until the 3rd day of life.     

Longitudinal study of vitamins A, E and lipid oxidative damage in human milk throughout lactation

Background

Little is known about the intensity of oxidative damage in human milk resulting from maternal oxidative stress. The aim of our study was to explore the changes in Total Antioxidant Status (TAS) and concentrations of antioxidative vitamins and isoprostanes (markers of oxidative stress) in human colostrum and mature milk.

Methods

The study included 49 postpartum women with normal, spontaneous full term delivery. The exclusion criteria included active and passive smoking, acute and chronic disorders, and pharmacotherapy other than vitamin supplementation. Colostrum samples were collected on the 3rd day after delivery and breast milk samples between the 30th and the 32nd day after delivery. TAS of colostrum/breast milk was determined by Rice-Evans and Miller method. The amount of vitamins A and E was measured by HPLC. Isoprostane concentrations in colostrum/mature milk and urine were determined immunoenzymatically.

Results

No significant differences were observed in maternal dietary intakes of vitamins A and E determined prior to the colostrum and mature milk sampling. The TAS of mature milk was significantly higher compared to colostrum (P = 0.002), while vitamin A and E concentrations were significantly lower (P = 0.003 and P = 0.001). Although the isoprostane concentration of mature milk was significantly higher than the colostrum concentration, this difference was not significant (P = 0.129).

Conclusion

Human milk is a source of antioxidative vitamins and their concentrations decrease throughout the lactation, while their total antioxidative properties increase. The phase of lactation does not affect the degree of human milk's lipid oxidative damage.     

Tri-iodothyronine and thyroxine in human milk

The concentration of tri-iodothyronine (T3) and thyroxine (T4) in human milk was determined by radioimmunoassay (RIA). The analysis of T3 was performed on unextracted milk and on ethanol extracts of defatted milk. Analysis of unextracted milk was complicated by artifacts. Reliable and reproducible results were achieved only with the milk extracts. In 10 colostral milk samples the mean T3 levels +/- SD were 0.80 +/- 0.52 nmol/l before feeding (early milk) and 0.93 +/- 0.62 after feeding (hind milk). The T3 concentration in colostrum did not change significantly during the feeding to the infant. In 12 mature milk samples collected between infant feedings, the mean T3 +/- SD was 1.19 +/- 0.42 nmol/l. T4 was not detected in any of the samples analysed (detection limit 3 nmol/l).     

Aluminum contents of human milk, cow's milk, and infant formulas

BACKGROUND: Aluminum toxicity is well documented and contamination of milk formulas has been implicated as the source of accumulation in bone and brain tissues. The purpose of the current study was to evaluate the aluminum contents of human milk, cow's milk, and infant formulas. METHODS: Aluminum contents were determined by atomic absorption spectrometry in samples of human milk in the colostrum, intermediate, and mature stages; infant formulas from eight manufacturers; and various types and brands of commercially available cow's milk. RESULTS: Mean aluminum concentration was lowest in human milk (23.4 +/- 9.6 microg/l), and did not differ significantly between colostrum, intermediate-stage and mature-stage milk. Mean aluminum concentration was 70 microg/l in cow's milk, and 226 microg/l in reconstituted infant formulas. Aluminum concentrations in infant formulas differed markedly among manufacturers; concentration in milk from one of the manufacturers was particularly high (mean, 551 microg/l; range, 302-1149 microg/l). These values are for milk reconstituted with aluminum-free water under laboratory conditions; formulas prepared with tap water in the University Hospital's infant-feeding unit had even higher aluminum content. Experiments showed that aluminum concentration in the high-aluminum milk could be reduced by more than 70% at the manufacturing stage, by using low aluminum components. CONCLUSIONS: The results of the present study support the recommendations for infant formula manufacturers to strive to reduce aluminum concentration in their products.     

上海地区人乳中脂肪酸成分的研究

目的对上海地区人乳脂肪酸成分再次进行调查,以获得上海地区人乳脂肪酸成分的最新数据。方法选择健康产妇31例,平均年龄(27±4)岁,平均孕期(39±1)周,婴儿平均出生体质量为(3 405±375)g。采集每位产妇产后1～7 d的初乳、14 d和28 d的过渡乳以及42 d的成熟乳,采用气相色谱法对人乳中的脂肪酸成分进行测定。结果人乳中的总脂肪酸含量从初乳、过渡乳到成熟乳逐渐增加;饱和脂肪酸的含量在1～7 d的初乳中逐渐增加,至过渡乳和成熟乳逐渐下降;单不饱和脂肪酸含量在1～7 d的初乳中逐渐降低,到过渡乳和成熟乳又逐渐升高;长链多不饱和脂肪酸、花生四烯酸(AA)和二十二碳六烯酸(DHA)的含量在初乳中很高,到成熟乳后明显降低,而必需脂肪酸、亚油酸(LA)和α-亚麻酸(ALA)则随哺乳期的延长逐渐增加。与10年前的上海人乳资料相比较,DHA含量有所增加,而ALA含量却有下降。结论人乳中的脂肪酸含量随哺乳期的延长不断发生变化。中国上海地区人乳中必需脂肪酸、LA的含量显著高于国外报道。     

Immune regulatory cytokines in the milk of lactating women from farming and urban environments

Peroni DG, Pescollderungg L, Piacentini GL, Rigotti E, Maselli M, Watschinger K, Piazza M, Pigozzi R, Boner AL. Immune regulatory cytokines in the milk of lactating women from farming and urban environments.
Pediatr Allergy Immunol 2010: 21: 977–982.
© 2010 John Wiley & Sons A/S Children living on farms have fewer allergies. It is unclear whether breastfeeding in different environments contributes to preventing allergies by exposing offspring to different cytokines that can modulate immune responses. The aim of this study was to quantify and compare levels of Transforming Growth Factor‐β1 (TGF‐β1) and Interleukin‐10 (IL‐10) in the colostrum and mature milk of mothers living in towns at sea level (references) and mothers on farms. Milk samples were collected within 3 days postpartum (colostrum) and at the first month of the baby’s life (mature milk). Sixty‐nine reference mothers and 45 farm mothers participated in the study. TGF‐β1 concentrations were significantly higher both in the colostrum (p < 0.05) and in mature milk (p < 0.05) of farm mothers. In the reference mothers, a significant decrease in TGF‐β1 concentrations was observed between colostrum (650, range 0–8000 pg/ml) and mature milk (250, range 0–8000 pg/ml) (p < 0.05). In farm mothers, TGF‐β1 concentrations were 1102 pg/ml (range 0–14,500) in colostrum and remained high in mature milk (821 pg/ml, range 0–14,650). IL‐10 concentrations were higher in the mature milk of farm mothers (p < 0.05). No significant differences in IL‐10 were observed between colostrum and mature milk in the control group (15 pg/ml, range 0–1800, and 0 pg/ml, range 0–230) or in farm mothers (9.5 pg/ml, range 0–1775, and 14.2 pg/ml, range 0–930), respectively. Exposure to a farm environment is associated with higher concentrations of TGF‐β1 and IL‐10 in breast milk when compared to exposure to an urban environment. Higher cytokine concentrations in breast milk may influence early modulation of the development of an immune response, leading to a reduced prevalence of allergy‐related diseases in farm children.     

The influence of parity, age and maturity of pregnancy on antimicrobial proteins in human milk

Sequential samples of colostrum, transitional and mature milk from 47 women were investigated to determine the concentrations of 11S IgA, IgG, IgM, alpha 1-antitrypsin, lactoferrin, lysozyme, B1A globulin (C3) and B1E globulin (C4) by single radial immunodiffusion. These were all found to be high in colostrum with a decline in concentration as lactation proceeds although a wide variation in concentration was noted between different individuals at any given post-partum time interval. For each time interval considered, parity, age and maturity of pregnancy did not appear to influence significantly the variation in protein concentrations. Statistical analyses of the results obtained from samples taken during the first four days of lactation, when protein concentrations were highest, showed that parity and age did influence the variation in antimicrobial protein concentrations when examined using an analysis of variance but significantly higher concentrations of protective proteins were not consistently seen in the milk from any one or more parity or age groups. Mean concentrations of all proteins excluding IgA were found to be greater in those women delivering before their expected date of confinement during the first four days of lactation. This was statistically significant for C3 and C4 and approaching significance (p less than 0.08) for alpha 1-antitrypsin.     

哈尔滨地区早产儿母乳营养素含量的调查研究

目的了解当前哈尔滨地区早产儿母乳中各种营养素的含量,为研制国内早产儿强化母乳提供科学依据,为更加合理喂养早产儿促进其健康成长提供科学依据。方法收集哈尔滨市四个地区62名产妇的乳汁(早产儿初乳32份、成熟乳28份;足月儿初乳及成熟乳各30份),测定乳汁中蛋白质、脂肪、钙、磷、镁、铜、铁、锌、锰的含量。结果哈尔滨地区早产儿母乳中蛋白质、磷、锌、镁在成熟乳期下降明显,铁、铜略有下降,但差异无统计学意义,脂肪、锰随泌乳期呈上升趋势,钙无明显变化。早产儿母乳在初乳及成熟乳期蛋白质含量均高于足月儿母乳,其他元素差异两者间无统计学意义。结论早产儿母乳中蛋白质、锌、脂肪含量在成熟乳阶段含量偏低,建议适当补充,注意喂养。