Human milk macronutrient analysis using point-of-care near-infrared spectrophotometry

Targeted fortification with human milk analysis: An opportunity for innovation

Human milk's variable macronutrient composition is a necessary consideration when caring for very low birthweight infants. Targeted fortification is the practice of fortifying human milk using its known composition from human milk analysis, rather than its assumed macronutrient values. Utilization of human milk analyzers to measure the protein, fat, lactose, and energy composition within human milk samples has allowed the translation of this practice into the clinical setting. This review discusses the rationale of why targeted fortification is an important practice, what barriers exist in its implementation in the clinical setting, and what research gaps remain to be addressed.

Near-Infrared Sensors for Onsite and Noninvasive Quantification of Macronutrients in Breast Milk

Breast milk is an optimal food that covers all the nutritional needs of the newborn. It is a dynamic fluid whose composition varies with lactation period. The neonatal units of hospitals have human milk banks, a service that analyzes, stores, and distributes donated human milk. This milk is used to feed premature infants (born before 32 weeks of gestation or weighing less than 1500 g) whose mothers, for some reason, cannot feed them with their own milk. Here, we aimed to develop near-infrared spectroscopy (NIRS) measures for the analysis of breast milk. For this purpose, we used a portable NIRS instrument scanning in the range of 1396-2396 nm to collect the spectra of milk samples. Then, different chemometrics were calculated to develop 18 calibration models with and without using derivatives and the standard normal variate. Once the calibration models were developed, the best treatments were selected according to the correlation coefficients (r²) and prediction errors (SECVs). The best results for the assayed macronutrients were obtained when no pre-treatment was applied to the NIR spectra of fat (r² = 0.841, SECV = 0.51), raw protein (r² = 0.512, SECV = 0.21), and carbohydrates (r² = 0.741, SECV = 1.35). SNV plus the first derivative was applied to obtain satisfactory results for energy (r² = 0.830, SECV = 9.60) quantification. The interpretation of the obtained results showed the richness of the NIRS spectra; moreover, the presence of specific bands for fat provided excellent statistics in quantitative models. These results demonstrated the ability of portable NIRS sensors in a methodology developed for the quality control of macronutrients in breast milk.

Using Nature to Nurture: Breast Milk Analysis and Fortification to Improve Growth and Neurodevelopmental Outcomes in Preterm Infants

Premature infants are born prior to a critical window of rapid placental nutrient transfer and fetal growth-particularly brain development-that occurs during the third trimester of pregnancy. Subsequently, a large proportion of preterm neonates experience extrauterine growth failure and associated neurodevelopmental impairments. Human milk (maternal or donor breast milk) is the recommended source of enteral nutrition for preterm infants, but requires additional fortification of macronutrient, micronutrient, and energy content to meet the nutritional demands of the preterm infant in attempts at replicating in utero nutrient accretion and growth rates. Traditional standardized fortification practices that add a fixed amount of multicomponent fortifier based on assumed breast milk composition do not take into account the considerable variations in breast milk content or individual neonatal metabolism. Emerging methods of individualized fortification-including targeted and adjusted fortification-show promise in improving postnatal growth and neurodevelopmental outcomes in preterm infants.

Challenges in providing adequate and reliable nutrition for extremely low birth weight infants

BACKGROUND

There is limited data on macronutrient content and its variability in mothers' milk of extremely low birth weight (ELBW) infants. The primary objectives were to determine the mean and the range of macronutrient content in milk from mothers of ELBW infants.

METHODS

A near-infrared milk analyzer was used to measure fat, protein and carbohydrate. Data is presented as mean ± SD, median, and minimum/maximum values. Intraclass correlation coefficients (ICC) and linear regression were used to examine differences between repeat analyses.

RESULTS

The mean GA and BW of infants were 25.6 ± 1.9 weeks and 678.6 ± 78.6 g respectively. The mean caloric content of 212 milk samples (10 infants) was 20.1 ± 5.4 cals/oz. The mean fat, protein and carbohydrate content were 3.2 ± 1.8, 1.6 ± 0.5 g% and 8.0 ± 0.8 g% respectively. Large subject to subject and day to day variations were observed. The range of calories, fat, protein and carbohydrate content were 10.4-42.3 cals/oz, 0.2-14.1, 0.6-3.3 and 6.4-13.7 g% respectively. Nearly half of all samples had 17 or less cals/oz and 10% had 15 or less cals/oz. There were no significant differences between repeat readings on a single sample.

CONCLUSIONS

Standard fortification in presence of significant variation in macronutrient and caloric content of mother's milk can lead to large day to day variation in macronutrient and caloric intake of ELBW infants. Clinical significance of variable intake from one day to another in infants at high risk of NEC and growth failure is unclear and needs further study.

Individualized versus standard diet fortification for growth and development in preterm infants receiving human milk

BACKGROUND

Human milk as compared to formula reduces morbidity in preterm infants but requires fortification to meet their nutritional needs and to reduce the risk of extrauterine growth failure. Standard fortification methods are not individualized to the infant and assume that breast milk is uniform in nutritional content. Strategies for individualizing fortification are available; however it is not known whether these are safe, or if they improve outcomes in preterm infants.

OBJECTIVES

To determine whether individualizing fortification of breast milk feeds in response to infant blood urea nitrogen (adjustable fortification) or to breast milk macronutrient content as measured with a milk analyzer (targeted fortification) reduces mortality and morbidity and promotes growth and development compared to standard, non-individualized fortification for preterm infants receiving human milk at < 37 weeks' gestation or at birth weight < 2500 grams.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 9), in the Cochrane Library; Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Daily and Versions(R); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL), on September 20, 2019. We also searched clinical trials databases and the reference lists of retrieved articles for pertinent randomized controlled trials (RCTs) and quasi-randomized trials.

SELECTION CRITERIA

We considered randomized, quasi-randomized, and cluster-randomized controlled trials of preterm infants fed exclusively breast milk that compared a standard non-individualized fortification strategy to individualized fortification using a targeted or adjustable strategy. We considered studies that examined any use of fortification in eligible infants for a minimum duration of two weeks, initiated at any time during enteral feeding, and providing any regimen of human milk feeding.

DATA COLLECTION AND ANALYSIS

Data were collected using the standard methods of Cochrane Neonatal. Two review authors evaluated the quality of the studies and extracted data. We reported analyses of continuous data using mean differences (MDs), and dichotomous data using risk ratios (RRs). We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

Data were extracted from seven RCTs, resulting in eight publications (521 total participants were enrolled among these studies), with duration of study interventions ranging from two to seven weeks. As compared to standard non-individualized fortification, individualized (targeted or adjustable) fortification of enteral feeds probably increased weight gain during the intervention (typical mean difference [MD] 1.88 g/kg/d, 95% confidence interval [CI] 1.26 to 2.50; 6 studies, 345 participants), may have increased length gain during the intervention (typical MD 0.43 mm/d, 95% CI 0.32 to 0.53; 5 studies, 242 participants), and may have increased head circumference gain during the intervention (typical MD 0.14 mm/d, 95% CI 0.06 to 0.23; 5 studies, 242 participants). Compared to standard non-individualized fortification, targeted fortification probably increased weight gain during the intervention (typical MD 1.87 g/kg/d, 95% CI 1.15 to 2.58; 4 studies, 269 participants) and may have increased length gain during the intervention (typical MD 0.45 mm/d, 95% CI 0.32 to 0.57; 3 studies, 166 participants). Adjustable fortification probably increased weight gain during the intervention (typical MD 2.86 g/kg/d, 95% CI 1.69 to 4.03; 3 studies, 96 participants), probably increased gain in length during the intervention (typical MD 0.54 mm/d, 95% CI 0.38 to 0.7; 3 studies, 96 participants), and increased gain in head circumference during the intervention (typical MD 0.36 mm/d, 95% CI 0.21 to 0.5; 3 studies, 96 participants). We are uncertain whether there are differences between individualized versus standard fortification strategies in the incidence of in-hospital mortality, bronchopulmonary dysplasia, necrotizing enterocolitis, culture-proven late-onset bacterial sepsis, retinopathy of prematurity, osteopenia, length of hospital stay, or post-hospital discharge growth. No study reported severe neurodevelopmental disability as an outcome. One study that was published after our literature search was completed is awaiting classification.

AUTHORS' CONCLUSIONS

We found moderate- to low-certainty evidence suggesting that individualized (either targeted or adjustable) fortification of enteral feeds in very low birth weight infants increases growth velocity of weight, length, and head circumference during the intervention compared with standard non-individualized fortification. Evidence showing important in-hospital and post-discharge clinical outcomes was sparse and of very low certainty, precluding inferences regarding safety or clinical benefits beyond short-term growth.

Infrared analyzers for the measurement of breastmilk macronutrient content in the clinical setting

INTRODUCTION

There is growing interest in the possibility of measuring the macronutrient content of human milk. Several studies that intend to validate commercially available human milk analyzers have been published with inconsistent results. This review will focus on currently available, verified methodologies for analyzing macronutrients in human milk.

AREAS COVERED

A literature search was conducted in the PubMed database. Five milk analyzers were chosen to be included in this review: MIRIS (Uppsala, Sweden) (seven articles found), Calais (Cleveland, United States) (four articles), SpectraStar (Brookfield, United States) (four articles), MilkoScan (Hillerdo, Denmark) (two articles), and Delta LactoScope (Stockholm, Sweden) (one article). The following information was extracted from published manuscripts: measuring device, sample preparation, purpose of the study, type of macronutrients studied, results, and conclusions.

EXPERT OPINION

Infrared spectroscopy can be an accurate and reliable technology for assessing the macronutrient content of human milk, specifically crude protein, and total fat. However, an optimal handling of samples, the development of standardized quality-control protocols, and an improvement in calibration procedures are required before the full implementation of infrared technology in neonatal units.

Macronutrient analysis of donor human milk labelled as 24 kcal/oz

OBJECTIVE

To measure the macronutrient content (MNC) of donor human milk labelled as 24 kcal/oz ("high-calorie DHM," hcDHM), compare to bank-labelled MNC, and examine variability of hcDHM MNC among milk banks.

STUDY DESIGN

MNC was measured with near-infrared spectroscopy for 75 convenience samples from five milk banks collected during September 2016-July 2017. Concordance of measured MNC with labelled values was evaluated using three different thresholds: within ±20%, similar to FDA labelling standards for class II nutrients in foods; ±10%; and ±5%.

RESULTS

Protein and caloric content differed significantly between measured and labelled values and varied significantly among milk banks. Measured caloric content ranged from 16.50 to 30.27 kcal/oz, with 89.3% of hcDHM samples within ±20%, 58.7% within ±10%, and 18.7% within ±5% of labelled content.

CONCLUSIONS

MNC of hcDHM used in clinical practice shows variation that may result in differences from desired diet. The clinical implications of such differences are unexplored.

Optimizing individual nutrition in preterm very low birth weight infants: double-blinded randomized controlled trial

OBJECTIVE

In preterm neonates fed human milk, fortification may be adjusted by (1) optimization, based on growth rate and serum nutrient analyses, or (2) individualization, based on serial milk nutrient analyses. The primary aim was to determine whether individualized plus optimized nutrition (experimental) improves velocity of weight gain and linear growth from birth to endpoint (36 weeks postmenstrual age or discharge) when compared with optimized nutrition alone (controls).

STUDY DESIGN

Double-blinded parallel group randomized trial in 120 neonates <29 weeks gestational age (GA) or <35 weeks and small for GA (birth weight < 10th centile).

RESULT

Weight-gain velocity (13.1 ± 2.1, n = 57 controls, vs. 13.0 ± 2.6 g kg^-1 day^-1, n = 59 experimental, P = 0.87), linear growth (0.9 ± 0.2, n = 55, vs. 0.9 ± 0.2 cm week^-1, n = 52, P = 0.90) and frequency of weight/length disproportion (2% vs. 2%, P = 0.98) were similar in both groups.

CONCLUSIONS

Individualized plus optimized nutrition does not improve weight gain, linear growth, or weight/length disproportion at endpoint versus optimized nutrition alone.

Accuracy and Reliability of Infrared Analyzers for Measuring Human Milk Macronutrients in a Milk Bank Setting

BACKGROUND

Infrared (IR) analysis is an emerging technology that may be a useful tool for milk banks to manage the nutrient variability in donor human milk.

OBJECTIVE

To evaluate the accuracy, reliability, and comparability of commercial infrared analyzers for measuring human milk macronutrients in a milk bank setting.

METHODS

Three nonprofit milk banks received blinded test kits of human milk that had been assessed using reference methods. Four infrared instruments were used to measure macronutrients as follows: 1 filtered mid-IR, 2 Fourier-transformed full-spectra mid-IR, and 1 near-IR. Twenty-five unique samples were read concurrently for the accuracy arm. An identical sample was read daily for 1 mo for the reliability arm.

RESULTS

Values for R 2 describing relationships with reference methods for total fat, crude protein, and lactose, were as follows: filtered mid-IR, 0.98, 0.94, and 0.48; Fourier-transformed full-spectra mid-IR, 0.97, 0.93, and 0.36 for instrument 1 and 0.98, 0.98, and 0.31 for instrument 2; and near-IR 0.93, 0.93, and 0.12. There was no significant difference between instruments for crude protein and total fat measurements. There were significant differences in carbohydrate measurements between instruments. For 1 mo of daily measurements in the reliability arm, CVs for filtered mid-IR were ≤4.6%, for Fourier-transformed full spectra mid-IR were ≤1.7%, and for near-IR were ≤5.1%.

CONCLUSIONS

Infrared analysis is an accurate and reliable method for measuring crude protein and total fat in a milk bank setting. Carbohydrate measurements are less accurate and are significantly different between instruments, which will likely lead to differences in derived calorie values.

Macronutrient Analysis of Target-Pooled Donor Breast Milk and Corresponding Growth in Very Low Birth Weight Infants

The macronutrient composition of target-pooled donor breast milk (DBM) (milk combined strategically to provide 20 kcal/oz) and growth patterns of preterm infants receiving it have not been characterized. Caloric target-pooled DBM samples were analyzed by near-infrared spectroscopy. Weekly growth velocities and anthropometric z-scores were calculated for the first 30 days and at 36 weeks corrected gestational age (CGA) for 69 very low birthweight (VLBW) infants receiving minimum one week of DBM. Samples contained mean 18.70 kcal/oz, 0.91 g/dL protein, 3.11 g/dL fat, 7.71 g/dL carbohydrate (n = 96), less than labeled values by 2.43 kcal/oz and 0.11 g/dL protein (p < 0.001). By week 3, growth reached 16.58 g/kg/day, 0.95 cm/week (length), and 1.01 cm/week (head circumference). Infants receiving <50% vs. >50% DBM had similar growth, but infants receiving >50% DBM were more likely to receive fortification >24 kcal/oz (83% vs. 51.9% in the <50% DBM group; p = 0.005). From birth to 36 weeks CGA (n = 60), there was a negative z-score change across all parameters with the greatest in length (−1.01). Thus, target-pooling does not meet recommended protein intake for VLBW infants. Infants fed target-pooled DBM still demonstrate a disproportionate negative change in length z-score over time.

Comparison of the Effect of Three Different Fortification Methods on Growth of Very Low Birth Weight Infants

BACKGROUND

This study aimed to compare the effects of adjustable fortification (AF), targeted fortification (TF), and standard fortification (SF) methods on the early growth of very low birth weight infants.

MATERIALS AND METHODS

Sixty infants <32 weeks of gestational age and weighing <1,500 g were selected. These infants were exclusively fed with breast milk and were randomized into three fortification groups: SF, AF, and TF. SF consists of adding a fixed amount of fortifier to maternal milk. Blood urea nitrogen levels are used to adjust fortifier in AF. In TF, breast milk is analyzed and fortified accordingly based on the macronutrient content to achieve the targeted intake.

RESULTS

A total of 76 preterm infants were eligible for the study. Sixty infants were randomized into three groups. At the end of the fourth week of fortification period, median daily weight gain of the infants was similar in the AF [23.5 g/(kg·d)] and TF groups [25.5 g/(kg·d)], and significantly higher in both groups than in SF group [12 g/(kg·d)] (AF versus SF group, p < 0.001 and TF versus SF group, p < 0.001). Weight, head circumference, and length were compared across the three groups regarding percentile. Significant improvement in the percentile groups of weight and head circumference was observed in the AF and TF groups. In the SF group, a significant decline in the percentile groups of weight, head circumference, and length was detected. Daily protein and energy intakes in AF and TF groups were significantly higher than those in SF group (SF versus AF, p < 0.001 and SF versus TF, p < 0.001).

CONCLUSIONS

Fortifying breast milk with AF and TF methods was found to improve body weight, length, and head circumference percentiles of preterm infants, whereas SF method was found unsatisfactory. To provide optimum growth for preterm babies, breast milk that has been fortified by using AF and TF strategies should be recommended in neonatal intensive care units.

Transmission infrared spectroscopy for rapid quantification of fat, protein, and lactose concentrations in human milk

OBJECTIVE

To develop partial least squares regression (PLSR) calibration models in combination with transmission infrared (TIR) spectroscopy for rapid and optimal quantification of human milk macronutrient concentrations.

STUDY DESIGN

Human milk samples (n = 306) were characterized simultaneously by reference chemical analytical methods and TIR spectroscopy. Reference macronutrient concentrations were linked to pre-processed spectra and divided into two (training and test) sets. PLSR was used to develop trial calibration models using training set, and the test set was used to assess the accuracy of the trial analytical methods.

RESULTS

For the methods selected as optimal, the concordance correlation coefficients between reference and TIR-based methods were 0.93 for fat, 0.96 for protein, and 0.52 for lactose. The Bland-Altman plots showed no evidence of systematic bias between TIR and reference methods.

CONCLUSIONS

TIR spectroscopy provides the basis for accurate and rapid quantification of human milk fat and protein concentrations but is less accurate for measuring lactose concentration.

Dose-response Relationship Between Donor Human Milk, Mother's Own Milk, Preterm Formula, and Neonatal Growth Outcomes

BACKGROUND

A dose-response relationship between proportions of donor human milk (DHM) intake and in-neonatal intensive care unit (in-NICU) growth rates, if any, remains poorly defined. Objective was to evaluate interrelationships between percentages of DHM, mother's own milk (MOM), and preterm formula (PF) intake and neonatal growth parameters at 36 weeks postmenstrual age or NICU discharge.

METHODS

Infants eligible for this single-center retrospective study were inborn at ≤32 weeks gestation or ≤1800 g, stayed in the NICU for ≥7 days, and received enteral nutrition consisting of human milk fortified with Enfamil human milk fortifier acidified liquid. Study exposures were defined as 10% increments in the total volumetric proportions of infant diet provided as MOM, DHM, or PF. Outcomes were growth parameters at 36 weeks postmenstrual age or NICU discharge. Multivariable linear regression modeled the adjusted additive effect of infant diet on individual growth parameters.

RESULTS

A total of 314 infants records were eligible for analysis. Using MOM as reference, the adjusted mean growth velocity for weight significantly decreased by 0.17 g · kg · day for every 10% increase in DHM intake, but did not vary with PF intake. The adjusted mean change in weight z score significantly decreased with increasing proportion of DHM intake but significantly improved with increasing PF intake. The adjusted mean head circumference velocity was significantly decreased by 0.01 cm/wk for every 10% increase in DHM intake, in reference to MOM, but did not vary with PF intake. Neither proportion of DHM nor PF intake was associated with length velocity.

CONCLUSIONS

When DHM and MOM are fortified interchangeably, preterm infants receiving incremental amounts of DHM are at increased risk of postnatal growth restriction. The dose-response relationship between DHM, MOM, and PF and long-term growth and neurodevelopmental outcomes warrants further research.

Neonatal Diabetes Mellitus

Neonatal diabetes is a rare cause of hyperglycemia in the neonatal period. It is caused by mutations in genes that encode proteins playing critical roles in normal functions of pancreatic beta cells. Neonatal diabetes is divided into temporary and permanent subtypes. Treatment is based on the correction of fluid-electrolyte disturbances and hyperglycemia. Patients respond to insulin or sulfonylurea treatment according to the mutation type. Close glucose monitoring and education of caregivers about diabetes are vital.

Validation of mid-infrared spectroscopy for macronutrient analysis of human milk

OBJECTIVE

Human milk has considerable variation in its composition. Hence, the nutrient profile is only an estimate and can result in under- or over-estimation of the intake of preterm infants. Mid-infrared (MIR) spectroscopy is an evolving technique for analyzing human milk but needs validation before use in clinical practice.

STUDY DESIGN

Human milk samples from 35 mothers delivering at 35 weeks to term gestation were analyzed for macronutrients by MIR spectroscopy and by standard laboratory methods using Kjeldahl assay for protein, Mojonnier assay for fat and high-pressure liquid chromatography assay for lactose.

RESULTS

MIR analysis of the macronutrients in human milk correlated well with standard laboratory tests with intraclass correlation coefficients of 0.997 for fat, 0.839 for protein and 0.776 for lactose. Agreement between the two methods was excellent for fat, and moderate for protein and lactose (P<0.001).

CONCLUSIONS

This methodological paper provides evidence that MIR spectroscopy can be used to analyze macronutrient composition of human milk. Agreement between the methodologies varies by macronutrient.

Wide Variability in Caloric Density of Expressed Human Milk Can Lead to Major Underestimation or Overestimation of Nutrient Content

BACKGROUND

Very-low-birth-weight infants continue to face significant difficulties with postnatal growth. Human milk is the optimal form of nutrition for infants but may exhibit variation in nutrient content.

OBJECTIVE

This study aimed to perform macronutrient analysis on expressed human milk from mothers whose babies are hospitalized in the neonatal intensive care unit.

METHODS

Up to five human milk samples per participant were analyzed for protein, carbohydrate, and fat content using reference chemical analyses (Kjeldahl for protein, high pressure liquid chromatography for carbohydrates, and Mojonnier for fat). Calorie content was calculated.

RESULTS

A total of 64 samples from 24 participants was analyzed. Wide variability was found in calorie, protein, carbohydrate, and fat composition. The authors found an average of 17.9 kcal/ounce, with only 34% of samples falling within 10% of the expected caloric density.

CONCLUSION

The assumption that human milk contains 20 kcal/ounce is no longer supported based on this study. This supports promoting an individualized nutrition strategy as a crucial aspect to optimal nutrition.

Assessment of human milk composition using mid-infrared analyzers requires calibration adjustment

OBJECTIVE

Nutrient composition of human milk (HM) is highly variable. Targeted HM fortification has been proposed to address these variations and reduce the cumulative nutritional deficit in preterm infants. Near-infrared analysis is used to measure the protein and fat content in HM; however, the reliability of this technique has not been evaluated. The objective of this study is to evaluate the reproducibility and accuracy of two generations of HM analyzers (HMA1 and HMA2) in estimating protein and lipid contents.

STUDY DESIGN

Reproducibility was assessed by analyzing in duplicate 146 and 128 HM samples with HMA1 and HMA2 (Miris), respectively. To evaluate the accuracy, lipid and protein concentrations were assessed in 31 and 39 samples using HMA1 or HMA2, respectively. Values were compared with measurements obtained using reference methods and correction equations were calculated. After applying the correction equations on 12 HM samples, the performance of the two devices were compared and the equation was validated according to the reference methods.

RESULTS

The coefficients of variation for protein and lipid assessments were below 3% for both HMA1 and HMA2. Protein concentrations were significantly underestimated by HMA2 (-0.53±0.23 g dl^-1). Lipid content was significantly overestimated by both devices, but the error was greater with HMA1 (0.76±0.48 g dl^-1) than with HMA2 (0.36±0.33 g dl^-1). Correction equations were specific for each generation of HMA. Finally, after correction, both instruments provided similar and accurate results.

CONCLUSION

HMAs require calibration adjustment before their use in clinical practice, to avoid inappropriate HM fortification.

"Bed Side" Human Milk Analysis in the Neonatal Intensive Care Unit: A Systematic Review

Human milk analyzers can measure macronutrient content in native breast milk to tailor adequate supplementation with fortifiers. This article reviews all studies using milk analyzers, including (i) evaluation of devices, (ii) the impact of different conditions on the macronutrient analysis of human milk, and (iii) clinical trials to improve growth. Results lack consistency, potentially due to systematic errors in the validation of the device, or pre-analytical sample preparation errors like homogenization. It is crucial to introduce good laboratory and clinical practice when using these devices; otherwise a non-validated clinical usage can severely affect growth outcomes of infants.

Fortification of human milk for preterm infants

Human milk is the preferred feeding for all infants, including those of very low birth weight (<1500 g). It has both nutritional and anti-infective properties which are especially important for infants at risk for sepsis and necrotizing enterocolitis. When maternal milk is not available or the amount produced is not sufficient to meet daily needs, donor human milk may (should) be used in its place. However, donor human milk is generally term in quality and likely has insufficient protein to promote appropriate growth. Whether donor or mother's own milk, fortification of human milk is required to meet nutrient requirements for growth and development for these preterm infants who are at high risk for growth faltering during the hospital stay. There are multiple strategies and products that may be employed to support desired growth rates. The advent of human milk analyzers may be helpful in a more customized approach to fortification.

Preterm human milk composition: a systematic literature review

There are wide variations in the macronutrient values adopted by neonatal intensive care units and industry to fortify milk in efforts to achieve recommended intakes for preterm infants. Contributing to this is the variation in macronutrient composition of preterm milk between and within mothers and the variable quality of milk analyses used to determine the macronutrient content of milk. We conducted a systematic review of the literature using articles published in English between 1959 and 2013 that reported the concentrations of one or more macronutrients or energy content in human preterm milk, sampled over a representative 24-h period. Searched medical databases included Ovid Medline, Scopus, CINAHL and the Cochrane Library. Results are presented as mean values and ranges for each macronutrient during weeks 1-8 of lactation, and preferred mean values (g/100 ml) for colostrum (week 1) and mature milk (weeks 2-8; protein: 1·27, fat: 3·46, lactose: 6·15 and carbohydrate: 7·34), using data from studies employing the highest-quality analyses. Industry-directed fortification practices using these mean values fail to meet protein targets for infants weighing <1000 g when the fortified milk is fed <170-190 ml/kg per d, and the protein:energy ratio of the fortified milk is inadequate. This study aimed to provide additional information to industry in order to guide their future formulation of breast milk fortifiers. Quality macronutrient analyses of adequately sampled preterm breast milk would improve our understanding of the level of fortification needed to meet recommended protein and energy intakes and growth targets, as well as support standardised reporting of nutritional outcomes.

Human Milk Analyser shows that the lactation period affects protein levels in preterm breastmilk

AIM

This study measured the composition of preterm human breastmilk, particularly the protein content, with the MIRIS Human Milk Analyser, compared our results with published values and determined the relationship between protein content and lactation period.

METHODS

We analysed 83 samples of 24-hour pooled human milk from 76 mothers who delivered preterm infants weighing under 1500 g at less than 32 weeks of gestational age. The milk's protein, fat and energy were measured by the MIRIS Human Milk Analyser and compared to reference values. The relationship between protein content and lactation period was quantified.

RESULTS

On average, the samples contained 1.1 ± 0.37 g (0.2-2.2 g) of protein, 3.2 ± 0.85 g (range 1.1-6.1 g) of fat, 6.6 ± 0.34 g of lactose (5.5-8.0 g) and 60 ± 11 kcal (39-94 kcal) of energy per 100 mL. The wide variations in macronutrient content were not influenced by the gestational age of the infant and the lactation day results from 70 of the mothers correlated inversely with the protein content (p < 0.0001; r = -0.42). The MIRIS proved useful, but some adjustments are needed.

CONCLUSION

Variations in macronutrients were high in the breastmilk of women who delivered preterm babies and the protein content decreased with lactation. With adjustments, the MIRIS might provide a helpful tool for individualised fortification.

Validation of Correction Algorithms for Near-IR Analysis of Human Milk in an Independent Sample Set-Effect of Pasteurization

Commercial infrared (IR) milk analyzers are being increasingly used in research settings for the macronutrient measurement of breast milk (BM) prior to its target fortification. These devices, however, may not provide reliable measurement if not properly calibrated. In the current study, we tested a correction algorithm for a Near-IR milk analyzer (Unity SpectraStar, Brookfield, CT, USA) for fat and protein measurements, and examined the effect of pasteurization on the IR matrix and the stability of fat, protein, and lactose. Measurement values generated through Near-IR analysis were compared against those obtained through chemical reference methods to test the correction algorithm for the Near-IR milk analyzer. Macronutrient levels were compared between unpasteurized and pasteurized milk samples to determine the effect of pasteurization on macronutrient stability. The correction algorithm generated for our device was found to be valid for unpasteurized and pasteurized BM. Pasteurization had no effect on the macronutrient levels and the IR matrix of BM. These results show that fat and protein content can be accurately measured and monitored for unpasteurized and pasteurized BM. Of additional importance is the implication that donated human milk, generally low in protein content, has the potential to be target fortified.

Human Milk Analysis Using Mid-Infrared Spectroscopy

BACKGROUND

The composition of human milk is known to vary with length of gestation, stage of lactation, and other factors. Human milk contains all nutrients required for infant health but requires fortification to meet the needs of low-birth-weight infants. Without a known nutrient profile of the mother's milk or donor milk fed to a baby, the composition of the fortified product is only an estimate. Human milk analysis has the potential to improve the nutrition care of high-risk newborns by increasing the information about human milk composition. Equipment to analyze human milk is available, and the technology is rapidly evolving. This pilot study compares mid-infrared (MIR) spectroscopy to reference laboratory milk analysis.

METHODS

After obtaining informed consent, we collected human milk samples from mothers of infants weighing <2 kg at birth. Duplicate samples were analyzed for macronutrients by MIR and by reference laboratory analysis including Kjeldahl for protein, Mojonnier for fat, and high-pressure liquid chromatography for lactose. Intraclass correlation coefficients, Bland-Altman scatter plots, and paired t tests were used to compare the two methods.

RESULTS

No significant differences were detected between the macronutrient content of human milk obtained by MIR vs reference laboratory analysis.

CONCLUSIONS

MIR analysis appears to provide an accurate assessment of macronutrient content in expressed human milk from mothers of preterm infants. The small sample size of this study limits confidence in the results. Measurement of lactose is confounded by the presence of oligosaccharides. Human milk analysis is a potentially useful tool for establishing an individualized fortification plan.

Implementation of a human milk management center

Current hospital practices surrounding the use of human milk and fortification are suboptimal. Safety of milk preparation should be a priority, as should optimization of the milk to meet the nutritional needs of hospitalized infants. This article describes the implementation of a human milk management center (HMMC) at a children's hospital. This centralized center allows for milk to be safely prepared under aseptic technique. In addition, the HMMC staff can analyze milk composition. The widely variable nutrient composition of human milk has been well established and, therefore, should be considered when fortifying human milk. The HMMC staff have the ability to perform creamatocrits on milk, conduct human milk nutrient analysis, and make skim milk for infants. The processes for developing an HMMC are also detailed in this article.

Fortification of human milk in very low birth weight infants (VLBW <1500 g birth weight)

The American Academy of Pediatrics supports the feeding of human milk for all infants. Very-low-birth-weight and extremely low-birth-weight infants especially can benefit from the immune and neurodevelopmental effects of human milk. However, human milk alone is nutritionally inadequate for the rapid growth of the very-low-birth-weight infant during a critical window for brain development and requires fortification to meet current recommendations. There are a variety of products, devices, and strategies that can be used to fine tune nutritional support of these very vulnerable infants.

Rapid measurement of macronutrients in breast milk: How reliable are infrared milk analyzers?

BACKGROUND & AIMS

Significant biological variation in macronutrient content of breast milk is an important barrier that needs to be overcome to meet nutritional needs of preterm infants. To analyze macronutrient content, commercial infrared milk analyzers have been proposed as efficient and practical tools in terms of efficiency and practicality. Since milk analyzers were originally developed for the dairy industry, they must be validated using a significant number of human milk samples that represent the broad range of variation in macronutrient content in preterm and term milk. Aim of this study was to validate two milk analyzers for breast milk analysis with reference methods and to determine an effective sample pretreatment. Current evidence for the influence of (i) aliquoting, (ii) storage time and (iii) temperature, and (iv) vessel wall adsorption on stability and availability of macronutrients in frozen breast milk is reviewed.

METHODS

Breast milk samples (n = 1188) were collected from 63 mothers of preterm and term infants. Milk analyzers: (A) Near-infrared milk analyzer (Unity SpectraStar, USA) and (B) Mid-infrared milk analyzer (Miris, Sweden) were compared to reference methods, e.g. ether extraction, elemental analysis, and UPLC-MS/MS for fat, protein, and lactose, respectively.

RESULTS

For fat analysis, (A) measured precisely but not accurately (y = 0.55x + 1.25, r(2) = 0.85), whereas (B) measured precisely and accurately (y = 0.93x + 0.18, r(2) = 0.86). For protein analysis, (A) was precise but not accurate (y = 0.55x + 0.54, r(2) = 0.67) while (B) was both precise and accurate (y = 0.78x + 0.05, r(2) = 0.73). For lactose analysis, both devices (A) and (B) showed two distinct concentration levels and measured therefore neither accurately nor precisely (y = 0.02x + 5.69, r(2) = 0.01 and y = -0.09x + 6.62, r(2) = 0.02 respectively). Macronutrient levels were unchanged in two independent samples of stored breast milk (-20 °C measured with IR; -80 °C measured with wet chemistry) over a period of 14 months.

CONCLUSIONS

Milk analyzers in the current configuration have the potential to be introduced in clinical routine to measure fat and protein content, but will need major adjustments.

Nutritional and immunological considerations relevant to infant nutrition

Optimal nutrition during infancy is critical not only to support the dramatic growth and development that takes place during the first 12 months following birth but also for establishing a healthy immune response throughout childhood and across the life span. The normative standards for infant feeding and nutrition are breast-feeding and human breast milk. However, in cases in which human breast milk is not available, infant formula is substituted. Providing optimal patient care that results in the best clinical outcomes depends on understanding the unique attributes of the 3 main sources of nutrition for newborns. This state of the science review provides an update on the macronutrient and immunological content of human milk, donor milk, and infant formula and highlights the relevance of these sources of infant nutrition on the development of immune system.

Challenges in the practice of human milk nutrition in the neonatal intensive care unit

The use of human milk for preterm infants has increased over the past decade reflecting an improved awareness of the benefits of human milk. Inherent in this paradigm shift is the recognition that human milk is a living tissue; full of immune cells, probiotics and hundreds of compounds that confer bioactivity and immune protective properties. Together these factors deliver a powerful effect in reducing clinical morbidities such as necrotizing enterocolitis and sepsis in the preterm infant. However, as breastfeeding is not possible for the very premature infant, human milk needs to be introduced in the neonatal intensive care unit through alternative means, resulting in significant handling and manipulation of maternal milk. This presents risks in quality control and provision of optimal nutrition delivery. Therefore, a comprehensive approach to standardizing preterm infant nutrition is essential to optimize the collection, storage, fortification and delivery of human milk to preterm neonates. In this paper we discuss the challenges presented by supporting human milk nutrition, and the rationale for the development of the Supporting Premature Infant Nutrition (SPIN) program at our institution.

Target fortification of breast milk with fat, protein, and carbohydrates for preterm infants

OBJECTIVES

Fortification of breast milk is an accepted practice for feeding very low birth weight infants, however, fixed dosage enhancement does not address variations in native breast milk. This could lead to deficiencies in calories and macronutrients. We therefore established the infrastructure for target fortification in breast milk by measuring and adjusting fat, protein, and carbohydrate content daily. We analyzed nutrient intake, growth, and safety variables.

STUDY DESIGN

Each 12-hour batch of breast milk was analyzed using near-infrared spectroscopy. Macronutrients were individually added to routine fortification to achieve final contents for fat (4.4 g), protein (3 g), and carbohydrates (8.8 g) (per 100 mL). Fully breast milk fed healthy very low birth weight infants (<32 weeks) were fed the fortified breast milk for at least 3 weeks. Matched pair analysis of 20 infants fed routinely fortified breast milk was performed using birth weight, gestational age, and postnatal age.

RESULTS

All 650 pooled breast milk samples required at least 1 macronutrient adjusted. On average, 0.3 ± 0.4 g of fat, 0.7 ± 0.2 g of protein, and 1.2 ± 0.2 g of carbohydrate were added. Biochemistry was normal in the 10 target fortified infants (birth weight: 860 ± 309 g, 26.3 ± 1.6 weeks gestational age); weight gain was 19.9 ± 2.7 g/kg/d; and milk intake was 147 ± 5 mL/kg/d (131 ± 16 kcal/kg/d). Osmolality of fortified breast milk was 436 ± 13 mOsmol/kg. Matched pair analysis of infants indicated a higher milk intake (155 ± 5 mL/kg/d) but similar weight gain (19.7 ± 3.3 g/kg/d). No adverse event was observed. The linear relationship between milk intake and weight gain observed in study babies but not seen in matched controls may be related to the variable composition of breast milk.

CONCLUSIONS

Daily target fortification can be safely implemented in clinical routine and may improve growth.

Establishment of micromethods for macronutrient contents analysis in breast milk

Commercially available milk analysers were originally developed for use in the dairy industry, but they are now used to analyse macronutrient content of breast milk in clinical studies and routine care of the premature or very low birthweight (VLBW) infants. Due to the different composition of cow and breast milk, these devices need to be validated against reference methods before they can be used in daily routine. However, current reference methods require a sample volume of 30-100 mL to analyse fat, protein and lactose. It is not feasible to obtain this volume of milk for research purposes, especially from VLBW infants as lactation may be delayed or impaired and the limited volume of breast milk must be provided to the infant. To support validation of milk analysers in both clinical and research settings, the aim of this study is to establish and validate micromethods for precise macronutrient analysis in small volume of breast milk and conduct a feasibility study of the micromethods as a post-validation. Methods include a modified Mojonnier ether extraction (fat), elemental analysis (protein) and ultra-performance liquid chromatography-tandem mass spectrometry (lactose). We were able to downsize volumes required for analysis of fat, protein and lactose to 1 mL, 260 μL and 100 μL; corresponding coefficients of variation are 1.7, 1.8 and 2.3%, respectively. The presented methods allow for reliable and precise analyses of macronutrients in ≤1.5 mL of breast milk and will be used to validate milk analysers.

Four-week nutritional audit of preterm infants born <33 weeks gestation

AIM

Preterm nutritional audits have previously been conducted using assumed milk composition. We audited protein and energy intakes in the first 28 days of preterm life using both assumed milk composition and milk analysis to assess their effect on weight gain and to determine if the recommended reasonable range of intakes were met.

METHODS

Parenteral and enteral intakes and weight gain were recorded daily for infants (n = 63) born <33 weeks gestation, using assumed milk composition. Macronutrient composition was determined by milk analysis for a subset of infants (n = 36). Linear mixed models analysis was used to assess the influence of energy and protein intakes on weight gain.

RESULTS

(Data median (range)): Infants (n = 63) gestation and birth weight were 30 (24-32) weeks and 1400 (540-2580) g, respectively. Macronutrient milk composition was variable: protein 16.6 (13.4-27.6) g/L, fat 46.1 (35.0-62.4) g/L, lactose 68.0 (50.9-74.8) g/L, energy 3074 (2631-3761) kJ/L. Intakes based on measured composition differed from assumed. Protein intake was significantly associated with weight gain. Compared to infants with longer gestations, those born <28 weeks gestation were fed lower volumes, were more reliant on parenteral nutrition, took an additional seven days to transition to fortified feeds and median weight gain velocity took a fortnight longer to reach targets.

CONCLUSION

Preterm milk composition is variable and routine fortification using assumed composition may result in inappropriate nutrition. Fortification regimens stratified by birth gestation may be necessary to achieve preterm nutrition and growth targets. Milk analysis is required for accurate nutritional audit.

Pooling expressed breastmilk to provide a consistent feeding composition for premature infants

OBJECTIVE

We hypothesized that pooling a mother's expressed breastmilk for 24 hours compared with individual pump session collection of milk would provide a more consistent caloric product without increasing bacterial contamination.

STUDY DESIGN

We investigated 24-hour pooled breastmilk collection by enrolling 19 mothers who were expressing milk for their infants. Mothers followed a standardized milk collection protocol for 4 study days: daily milk was pooled in a sterile 1-L bottle on Day 1, and on Day 2 milk was aliquoted for each pump session into a sterile 120-mL container. The next week the order of collection was reversed. Milk samples were plated, incubated, and evaluated for bacteria colonization. Milk samples were analyzed for protein, fat, and carbohydrate content.

RESULTS

There was inherently less variability in the caloric and nutrient content of pooled milk compared with individual samples, in which caloric density varied by as much as 29%. Mother's milk had highly variable bacterial counts ranging from 0 to greater than 100,000 colonies/mL. High bacteria counts (>100,000 colonies/mL) occurred in 14.7% (31 of 211) of individual samples compared with 8.6% (three of 35) of pooled samples (p=0.39).

CONCLUSIONS

Twenty-four-hour pooling of human milk reduces nutrient and caloric variability without increasing bacterial counts.

Comparison of mid-infrared transmission spectroscopy with biochemical methods for the determination of macronutrients in human milk

The variability of human milk (HM) composition renders analysis of its components essential for optimal nutrition of preterm fed either with donor's or own mother's milk. To fulfil this requirement, various analytical instruments have been subjected to scientific and clinical evaluation. The objective of this study was to evaluate the suitability of a rapid method for the analysis of macronutrients in HM as compared with the analytical methods applied by cow's milk industry. Mature milk from 39 donors was analysed using an infrared human milk analyser (HMA) and compared with biochemical reference laboratory methods. The statistical analysis was based on the use of paired data tests. The use of an infrared HMA for the analysis of lipids, proteins and lactose in HM proved satisfactory as regards the rapidity, simplicity and the required sample volume. The instrument afforded good linearity and precision in application to all three nutrients. However, accuracy was not acceptable when compared with the reference methods, with overestimation of the lipid content and underestimation of the amount of proteins and lactose contents. The use of mid-infrared HMA might become the standard for rapid analysis of HM once standardisation and rigorous and systematic calibration is provided.

Evaluation of human milk fortification from the time of the first feeding: effects on infants of less than 31 weeks gestational age

OBJECTIVE

To determine whether human milk fortification from the time of the first feeding significantly improves weight gain and bone mineral status in infants of <31 weeks estimated gestational age as compared with delayed or standard human milk fortification.

STUDY DESIGN

This was a retrospective pre-post design. In all, 95 infants born at <31 weeks estimated gestational age were compared. There were 53 infants in the early fortification group (EFG) and 42 infants in the delayed fortification group (DFG). They were compared with regard to weight gain at 34 weeks postmenstrual age (PMA), and their serum levels of calcium, phosphorus and alkaline phosphatase levels were compared as an indicator of bone mineral status. The practice change of fortifying all human milk given to preterm infants at <34 weeks PMA commenced in June 2009. The usual practice of fortification took place once an infant had reached a feeding volume of 50 to 100 ml kg(-1) per day. The new practice fortified all human milk with a powdered human milk fortifier to 24 calories per ounce, starting with the first feeding, no matter how small the volume.

RESULT

There were no differences in weight gain between the EFG and the DFG. The group that received fortification from the time of the first feeding were significantly less likely to have alkaline phosphatase levels >500 U l(-1) from 33 weeks PMA onward. There was no incidence of feeding intolerance with early fortification.

CONCLUSION

Fortification of human milk from the time of the first feeding does not affect weight gain at 34 weeks PMA, but is related to a lower incidence of elevated alkaline phosphate levels and does not cause feeding intolerance.

Management of diabetes mellitus in infants

Diabetes mellitus diagnosed during the first 2 years of life differs from the disease in older children regarding its causes, clinical characteristics, treatment options and needs in terms of education and psychosocial support. Over the past decade, new genetic causes of neonatal diabetes mellitus have been elucidated, including monogenic β-cell defects and chromosome 6q24 abnormalities. In patients with KCNJ11 or ABCC8 mutations and diabetes mellitus, oral sulfonylurea offers an easy and effective treatment option. Type 1 diabetes mellitus in infants is characterized by a more rapid disease onset, poorer residual β-cell function and lower rate of partial remission than in older children. Insulin therapy in infants with type 1 diabetes mellitus or other monogenic causes of diabetes mellitus is a challenge, and novel data highlight the value of continuous subcutaneous insulin infusion in this very young patient population. Infants are entirely dependent on caregivers for insulin therapy, nutrition and glucose monitoring, which emphasizes the need for appropriate education and psychosocial support of parents. To achieve optimal long-term metabolic control with low rates of acute and chronic complications, continuous and structured diabetes care should be provided by a multidisciplinary health-care team.