Fortification of human milk: evaluation of a novel fortification scheme and of a new fortifier

Human Milk Fortification for Very Preterm Infants: Toward Optimal Nutrient Delivery, Neonatal Intensive Care Unit Growth, and Long-Term Outcomes

Human milk is the preferred diet for very preterm infants due to short-term and long-term benefits for health and neurodevelopment. Fortification of human milk is required to deliver sufficient nutrients to attain recommended growth targets during the neonatal hospitalization. Intrinsic variability in human milk composition poses a challenge in clinical practice because some infants fail to meet recommended nutrient intakes even with existing approaches of standard (fixed-dose) and adjustable fortification. Individually targeted fortification is an emerging strategy to minimize nutrition delivery gaps through application of point-of-care human milk analysis and has potential to improve growth and related outcomes.

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.

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.

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.

What should be the protein target for adjustable Human Milk fortification in premature infants?

Objective:

To assess the short- and long-term effects of the adjustable fortification (ADJ) regimen on growth parameters in premature infants and to evaluate the amount of protein supplements given to reach the targeted blood urea nitrogen (BUN) levels.

Methods:

In this retrospective study, preterm babies who were born at ≤32 weeks gestational age and fed with human milk, were evaluated in two groups. Infants in Group-I were fed only standard fortification (STD). Infants in Group-II were fed the ADJ regimen. The study was conducted between 2011 and 2016.

Results:

There were 123 infants in the STD group and 119 in the ADJ group. The mean gestational age of the patients in Group-I was 29.7±1.8 weeks, and mean birth weight was 1266.1±347.1 g. The mean gestational age of the patients in Group-II was 29.5±1.9 weeks, and the mean birth weight was 1217.5±345.5 g. The daily increase in weight and weekly increase in HC were significantly higher in the ADJ group infants. Weight and HC of infants in the ADJ group were significantly higher at 40 weeks. At one year corrected age, weight, length, and HC measurements of both groups were similar. In Group-II, 63% of patients required additional protein supplementation up to 1.6 g/day to achieve the target BUN levels.

Conclusion:

A higher protein intake through the ADJ regimen improves the physical growth rate of premature infants in the NICU and after discharge. However, sometimes, the targeted growth and BUN values cannot be achieved despite the administration of protein at the recommended increased doses. Increasing protein supplementation up to 1.6 g/day is safe, feasible, and beneficial for these infants.

Commencing Nutrient Supplements before Full Enteral Feed Volume Achievement Is Beneficial for Moderately Preterm to Late Preterm Low Birth Weight Babies: A Prospective, Observational Study

The aim of this study was to observe after following a routine change in the feeding protocol whether the earlier introduction of nutrient supplements improved nutritional outcomes in moderately preterm to late preterm low birth weight (LBW) babies. In this prospective observational study, LBW babies between 31 and 39 weeks’ gestation admitted to a Special Care Nursery were assigned to two groups (F80, n = 45, F160, n = 42) upon commencing nutrient supplement at total fluid intake achievement of 80 or 160 mL/kg/day. Outcomes included weight, protein intake, biochemical markers, feeding intolerance, and length of stay (LOS). F80 nutrient supplements commenced before F160 (2.8 vs. 6.7 days, p < 0.0001) and lasted longer (15.2 vs. 12.2 days, p < 0.03). Weight gain velocity and LOS were similar. F80 mean protein intake during the first 10 days was higher (3.38 vs. 2.74 g/kg/day, p < 0.0001). There were fewer infants with protein intake <3 g/kg/day in the F80 group (8% vs. 65%, p < 0001). F80 babies regained birthweight almost two days earlier (7.5 vs. 9.4 days, p < 0.01). Weight gain Z-scores revealed an attenuation of the trend towards lower weight percentiles in the F80 group. Feeding intolerance was decreased for F80 (24.4% vs. 47.6%, p < 0.03). There were no adverse outcomes. Earlier nutrient supplementation for LBW babies lifts mean protein intake to above 3 g/kg/day and reduces both the duration of post-birth weight loss and incidence of feeding intolerance.

Feeding the feeble: steps towards nourishing preterm infants

This paper describes historic steps in feeding techniques and knowledge on the nutritional needs of premature infants. Devices to overcome weak sucking and swallowing were developed from 1851 to 1920, including tube feeding by gavage, medicine droppers and pipettes, feeding bottles with an air inlet, and beaked spoons for nasal feeding. Indwelling nastrogastric tubes were in use from 1951. For alleged safety concerns in the 1950s, postnatal feeding was postponed until a week of starvation was reached, and studies showed an association with neurological handicaps. The premature infant's elevated need for energy, protein, and minerals has been established since 1919. However, these remained controversial, and nutritional practices continued to lag behind theoretical knowledge. Concentrated formula was developed in the 1940s, parenteral supplementation in the 1960s, and human milk fortifiers in the 1970s. In the 1990s, necrotizing enterocolitis was found to be more frequent in infants who were fed formula than in those who were fed human milk. Recently, probiotics were shown to reduce the risk of necrotizing enterocolitis. Nevertheless, compared with other aspects of neonatal medicine, there is still remarkably little evidence on how to feed preterm infants.

Individualized fortification of breast milk in 41 Extremely Low Birth Weight (ELBW) preterm infants

BACKGROUND

The use of breast milk presents numerous early and long-term advantages for ELBW preterms. However, breast milk without fortification does not cover the high nutritional needs of such patients. The aim of our study was to assess the effect of individualized fortification of breast milk on the growth of ELBWs hospitalized in a neonatal intensive care unit (NICU).

METHODS

Retrospective single-center observational study.

RESULTS

We assessed the growth of 41 consecutive ELBWs (21 females, 20 males) with gestational ages between 23 and 30 weeks (mean GA 26.31±1.8) fed with breast milk in an individualized way. The rate of growth as the mean weight increase with breast milk fortification was 16.04±3.13 g/kg/day, more than the growth of the fetus in the uterus (~15 g/kg/day). This result was confirmed also among the ELBWs of lower GA. However, only 24.4% of all the ELBWs at the time of discharge from the NICU presented an appropriate weight for their gestational age. No cases of Necrotizing Enterocolitis (NEC) were observed.

CONCLUSIONS

Despite high growth velocity, the ELBWs failed to remain in the same percentiles of birth and, at discharge, only 27.7% had a weight of >10 centiles. Further studies are needed to improve growth during early critical phases of development.

Protein Intake and Growth in Preterm Infants: A Systematic Review

Objective. This review aimed to investigate the relationship between varying levels of enteral protein intake and growth in preterm infants, regardless of feeding method. Data Sources. Electronic databases were searched for relevant studies, as were review articles, reference lists, and text books. Study Selection. Trials were included if they were randomized or quasirandomized, participants were <37 weeks gestation at birth, and protein intakes were intentionally or statistically different between study groups. Trials reporting weight, length, and head circumference gains in infants fed formula, human milk, or fortified human milk were included. Data Extraction. Studies were categorized by feeding-type and relevant data were extracted into summary tables by one reviewer and cross-checked by a second. Data Synthesis. A meta-analysis could not be conducted due to extensive variability among studies; thus, results were synthesized graphically and narratively. Twenty-four trials met the inclusion criteria and were included in a narrative synthesis and 19 in a graphical synthesis of study results. Conclusions. There was extensive variability in study design, participant characteristics, and study quality. Nonetheless, results are fairly consistent that higher protein intake results in increased growth with graphical representation indicating a potentially linear relationship. Additionally, intakes as high as 4.5 g/kg/day were shown to be safe in infants weighing >1000 g.

Considerations in meeting protein needs of the human milk-fed preterm infant

Preterm infants provided with sufficient nutrition to achieve intrauterine growth rates have the greatest potential for optimal neurodevelopment. Although human milk is the preferred feeding for preterm infants, unfortified human milk provides insufficient nutrition for the very low-birth-weight infant. Even after fortification with human milk fortifier, human milk often fails to meet the high protein needs of the smallest preterm infants, and additional protein supplementation must be provided. Although substantial evidence exists to support quantitative protein goals for human milk-fed preterm infants, the optimal type of protein for use in human milk fortification remains uncertain. This question was addressed through a PubMed literature search of prospective clinical trials conducted since 1990 in preterm or low-birth-weight infant populations. The following 3 different aspects of protein quality were evaluated: whey-to-casein ratio, hydrolyzed versus intact protein, and bovine milk protein versus human milk protein. Because of a scarcity of current studies conducted with fortified human milk, studies examining protein quality using preterm infant formulas were included to address certain components of the clinical question. Twenty-six studies were included in the review study. No definite advantage was found for any specific whey-to-casein ratio. Protein hydrolyzate products with appropriate formulations can support adequate growth and biochemical indicators of nutrition status and may reduce gastrointestinal transit time, gastroesophageal reflux events, and later incidence of atopic dermatitis in some infants. Plasma amino acid levels similar to those of infants fed exclusive human milk-based diets can be achieved with products composed of a mixture of bovine proteins, peptides, and amino acids formulated to replicate the amino acid composition of human milk. Growth and biochemical indicators of nutrition status are similar for infants fed human milk fortified with human milk protein and bovine milk protein.

An intention to achieve better postnatal in-hospital-growth for preterm infants: adjustable protein fortification of human milk

OBJECTIVE

We assessed the effect of human milk (HM) fortification with extra protein supplement by an adjustable protein fortification method according to the weekly blood urea nitrogen (BUN) levels on growth in hospitalized preterm infants.

METHOD

A prospective observational intervention study in 58 preterms born ≤32 weeks of gestation and fed with breast milk was conducted. Preterms who were given a commercial HM fortifier which provides an additional protein of 0.8 g/3 scales according to the standard feeding strategy served as a historical control group. Infants who were given extra protein in addition to the HM fortifier with another commercial protein supplement which provides an additional protein of 2.2g/1 scale comprised the intervention group. Additional protein supplementation was adjusted according to BUN levels weekly in the intervention group. Weight gain velocities (g/kg/day), length, head circumferences (HC) gain velocities (mm/day) and daily growth indexes for weight, height and HC (percentage per day) were calculated.

RESULTS

The median amount of daily enteral protein intake [4 (3.4-4.6) vs. 2.78 (2.1-3.1) g/kg/day, p < 0.0001] was significantly higher in the interventional group. Length (p = 0.008) and HC (p < 0.0001) gain velocities were significantly higher in the intervention group. Daily growth indexes for weight (2.2% vs. 1.8%, p = 0.026), for length (0.4% vs. 0.3%, p = 0.027) and for HC (0.48% vs. 0.36% per day, p = 0.003) were significantly higher in the intervention group.

CONCLUSION

A higher protein intake by adjustable protein fortification method without energy or volume change leads to improved postnatal in-hospital-growth in very low birth weight infants.

Effect of increasing protein content of human milk fortifier on growth in preterm infants born at <31 wk gestation: a randomized controlled trial

BACKGROUND

Preterm human milk-fed infants often experience suboptimal growth despite the use of human milk fortifier (HMF). The extra protein supplied in fortifiers may be inadequate to meet dietary protein requirements for preterm infants.

OBJECTIVE

We assessed the effect of human milk fortified with a higher-protein HMF on growth in preterm infants.

DESIGN

This is a randomized controlled trial in 92 preterm infants born at <31 wk gestation who received maternal breast milk that was fortified with HMF containing 1.4 g protein/100 mL (higher-protein group) or 1.0 g protein/100 mL (current practice) until discharge or estimated due date, whichever came first. The HMFs used were isocaloric and differed only in the amount of protein or carbohydrate. Length, weight, and head-circumference gains were assessed over the study duration.

RESULTS

Length gains did not differ between the higher- and standard-protein groups (mean difference: 0.06 cm/wk; 95% CI: -0.01, 0.12 cm/wk; P = 0.08). Infants in the higher-protein group achieved a greater weight at study end (mean difference: 220 g; 95% CI: 23, 419 g; P = 0.03). Secondary analyses showed a significant reduction in the proportion of infants who were less than the 10th percentile for length at the study end in the higher-protein group (risk difference: 0.186; 95% CI: 0.370, 0.003; P = 0.047).

CONCLUSIONS

A higher protein intake results in less growth faltering in human milk-fed preterm infants. It is possible that a higher-protein fortifier than used in this study is needed. This trial was registered with the Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au/) as ACTRN12606000525583.

Fortification of maternal milk for very low birth weight (VLBW) pre-term neonates

Human milk is the best food for all neonates; however, in pre-term infants, especially those with a very low birth weight, it may lead to insufficient intake of protein and energy. The use of fortified human milk produces adequate growth in premature infants and satisfies the specific nutritional requirements of these babies. To improve the nutritional management of pre-term infants < or =35 weeks' gestational age, an individualised human milk fortification system based on the analysis of maternal milk was evaluated.

Optimization of human milk fortification for preterm infants: new concepts and recommendations

Preterm infants fed fortified human milk (HM) in standard (STD) fashion grow slower than preterm formula fed infants. Recently, low protein intake has been proven to be the primary limiting factor responsible for this growth failure. The main reason of protein undernutrition despite fortification is that STD fortification is based on the customary assumptions about the composition of HM. However, the protein concentration of preterm HM is variable and decreases with the duration of lactation. Also, the protein concentration of banked donor milk, which is most often provided by mothers of term infants, is likely to be lower. Hence, most of the HM fed to preterm infants during the fortification period is likely to have an inadequately low protein concentration. This hypothesis has been confirmed very recently by comparing the assumed and actual protein intakes in preterm infants fed fortified HM. Novel fortification models have been devised to deal with the problem of ongoing protein undernutrition. Individualized fortification is the recommended method to optimize HM fortification. There are two models of individualization: "adjustable fortification" and "targeted fortification". Both ways are feasible and effective in improving protein intakes and growth. Adjustable fortification has the advantage of being practical and avoids excessive protein intakes.

Optimal protein and energy intakes in preterm infants

There is compelling evidence that current nutritional practice fails to provide sufficient dietary protein for preterm infants, especially extremely and very low birth weight infants. Nutrient requirements can be estimated by a variety of techniques, but most suggest that these infants will require a protein intake of 3.5-4.0 g/kg/d. Even when these infants are able to tolerate full enteral feeds, most currently available artificial milk formula or breast milk fortifiers will not ensure these protein requirements are met except when fed at high volumes. Energy requirements on the other hand may be currently met, and evidence from controlled studies suggests that intakes higher than 110-135 kcal/kg/d might not be beneficial. The data from studies on neonatal adiposity outcomes, and from studies examining relationship between early growth and later cardiovascular outcome, also suggest that excess nutrient intake might be harmful. In the light of this data, optimal intakes and protein-energy ratios require re-appraisal.

The corrected blood urea nitrogen predicts the developmental quotient of extremely low-birth-weight infants at the corrected age of 36 months

BACKGROUND

Currently, there are no nutritional indices to predict cognitive function in extremely low-birth-weight (ELBW) infants.

OBJECTIVE

To assess the neonatal blood urea nitrogen (BUN) values in ELBW infants according to their cognitive function at the corrected age of 36 months.

METHODS

This was a retrospective study that assessed the neonatal factors affecting the developmental outcome in two groups "developmental quotient (DQ)> or =80" and "DQ<80", the groups were divided based on the DQ at the corrected age of 36 months. Between 1996 and 1999, 178 ELBW infants born at <28 weeks of gestation were admitted to our neonatal intensive care unit (NICU), of these, 32 died. Of the surviving 146 infants, 37 infants without any exclusion criteria (that would affect the cognitive function and BUN) except the nutritional factor, were assessed. Area under the curve (AUC) of corrected BUN (CBUN: BUN x 0.5/serum creatinine) from 28 to 84 days of life was used as an index of protein intake.

RESULTS

No significant differences were observed between the two groups with regard to the gestational age, birth weight, Z score of birth weight, and sex. However, compared to 15 infants with DQ<80, 22 infants with DQ> or =80 had significantly shorter duration of artificial ventilation and O(2) supplementation, a higher Apgar score at 5 min, and a higher AUC of CBUN. On multiple regression analysis, DQ> or =80 was observed to be significantly correlated with the AUC of CBUN (Odd's ratio 1.03, 95% confidence interval: 1.002-1.06).

CONCLUSION

The CBUN level would provide an estimate of adequate protein intake and the subsequent development of an ELBW infant.

Enteral intake for very low birth weight infants: what should the composition be?

Providing optimal nutrition to satisfy the growth needs of very low birth weight infants is critical. The available preterm formulas and fortified human milk diets provide protein intakes of approximately 3.5 to 3.6 g/kg/d when volumes sufficient to provide 120 kcal/kg/d are fed to these infants. These intakes support growth and protein accretion at about or slightly greater than intrauterine rate and lead to relatively increased fat deposition. However, most very low birth infants fed these diets remain below the 10th percentile of the intrauterine growth standards at discharge. There is clear evidence that, with respect to growth, very low birth infants are likely to benefit from a higher protein intake; however, there is no clear evidence that energy intakes greater than 120 kcal/kg/d are needed. Although the upper limit of protein intake and the ideal protein:energy ratio remain controversial, there is enough evidence to support the beneficial and safe use of formulas providing protein:energy ratio of 3.2 to 3.3 g/100 kcal.

Anthropometric and laboratory assessment of very low birth weight infants: the most helpful measurements and why

Very low birth weight (VLBW; < or =1500 g), preterm infants have numerous physiological and developmental concerns, including growth and the provision of adequate nutrients to sustain growth. Growth is an important health care outcome measure for VLBW infants. Provision of energy and nutrients at levels to support growth and development is the goal of nutrition support for VLBW infants. Anthropometry and laboratory data are useful components of growth and nutrition assessment. The objectives of this paper are to describe: 1) the clinical application and interpretation of anthropometric measures of growth, and 2) the utilization and interpretation of laboratory tests of nutritional status in VLBW infants.

Adjustable fortification of human milk fed to preterm infants: does it make a difference?

BACKGROUND

Inadequate nutrition leading to growth failure is common among premature infants. Although fortified breast milk (breast milk plus commercially prepared fortifier) is the preferred feeding, nutrient intakes achieved with fortified breast milk fall short of meeting nutrient needs. This is mainly due to inadequate protein content of fortifiers and variability in composition of expressed breast milk.

OBJECTIVE

A new adjustable fortification regimen has been designed to ensure that protein needs of premature infants are met at all times. The new regimen encompasses increasing the amount of fortifier and adding extra protein to breast milk guided by periodic determinations of blood urea nitrogen (BUN). The study tested the hypothesis that infants fed according to the new regimen have higher protein intakes and improved weight gain compared to infants fed according to standard fortification regimen.

METHODS

In a prospective, controlled trial, preterm infants with birth weights of 600-1750 g and gestational ages between 26 and 34 weeks were fed their own mother's milk or banked donor milk or both. Infants were randomly assigned before 21 days of age to either the new adjustable fortification regimen or the standard regimen. The study period began when feeding volume reached 150 ml/kg/day and ended when infants reached a weight of 2000 g. Standard fortification (STD) consisted in the use of the recommended amount of fortifier. Adjustable fortification (ADJ) consisted in the use, in addition to standard fortification, of extra fortifier and supplemental protein guided by twice-weekly BUN determinations. The primary outcome was weight gain, with serum biochemical indicators and nutrient intakes as secondary outcomes.

RESULTS

Thirty-two infants completed the study as planned (16 ADJ, 16 STD). Infants receiving the ADJ regimen had mean protein intakes of 2.9, 3.2 and 3.4 g/kg/day, respectively, in weeks 1, 2 and 3, whereas infants receiving the STD regimen had intakes of 2.9, 2.9, 2.8 g/kg/day, respectively. Infants on the ADJ regimen showed significantly greater gain in weight (17.5+/-3.0 vs 14.4+/-3.0 g/kg/day, P<0.01) and greater gain in head circumference (1.4+/-0.3 vs 1.0+/-0.3; P<0.05) than infants on the STD regimen. Weight and head circumference gain were significantly (P<0.05) correlated with protein intake. No significant correlations were found between growth parameters and intake of fat and energy. There were no significant differences between groups in BUN and other serum chemical values. In the ADJ group, BUN concentrations increased significantly (P<0.001) over time but were not significantly higher than in the STD group.

CONCLUSION

Premature infants managed with the new adjustable fortification regimen had significantly higher weight and head circumference gains than infants managed with standard fortification. Higher protein intake appears to have been primarily responsible for the improved growth with the adjustable regimen. The new fortification method could be a solution to the problem of protein undernutrition among premature infants fed human milk.

High protein pre-term infant formula: effect on nutrient balance, metabolic status and growth

Several lines of evidence suggest that formula with protein content of 3.0 g/100 kcal does not fully meet the protein needs of very-low-birth weight infants. Our purpose was to compare nitrogen balance, metabolic status and growth in infants fed a standard (3.0 g/100 kcal; RegPro) and high (3.6 g/100 kcal; HiPro) protein infant formula. Infants were fed both formulas, each formula for one week in balanced cross-over design. Metabolic status was monitored throughout. Nutrient balance and plasma amino acids were determined at the end of each week. Data were analysed using a linear mixed model. Eighteen infants were studied. Nine infants received the RegPro and nine received HiPro formula first. Nitrogen intake, absorption and retention were greater with the HiPro formula. None of the infants developed uremia or metabolic acidosis but retinol-binding-protein and weight gain were greater with the HiPro formula. Increased protein accretion paralleled by better weight gain without evidence of metabolic stress indicates that a formula with a protein content of 3.6 g/100 kcal better meets protein needs in these rapidly-growing infants. Further studies are needed to determine whether these short-term outcomes will be translated into long-term benefits.

The role of serum and urinary urea in the evaluation of enteral protein intake in adequate and small-for-gestational-age very low birth weight infants

CONTEXT AND OBJECTIVE

Very low birth weight (VLBW) infants have special nutritional needs. There is a current tendency to individualize their protein needs. The objective of this study was to determine the suitability of serum and urinary urea as indicators for protein intake in adequate-for-gestational-age (AGA) and small-for-gestational-age (SGA) VLBW infants.

DESIGN AND SETTING

Prospective study in the nursery attached to the Maternity Ward of the "Prof. Pedro de Alcântara" Children's Institute, Hospital das Clínicas, Department of Pediatrics, Faculdade de Medicina da Universidade de São Paulo, Brazil.

METHODS

Seventy-two VLBW infants (mean protein intake = 3.7 mg/kg/day) were enrolled in a prospective cohort study in two groups: AGA (n = 34) and SGA (n = 38). Blood samples, six-hour urine (6hUr) collections and urine sample tests (STUr) were obtained for urea and creatinine assays at three and five weeks of life.

STATISTICAL ANALYSIS

Student's t test, Pearson correlation and linear regression (p < 0.05).

RESULTS

There were no differences between groups for serum urea, 6hUr and STUr, or between two assessments within each group. Serum urea correlated with 6hUr in both AGA and SGA, and to STUr in SGA; 6hUr correlated with STUr in both AGA and SGA. There was no correlation between protein intake and serum or urine urea.

CONCLUSIONS

Serum and urinary urea did not reflect protein intake when mean intakes of 3.7 g/kg/day were used. Sample tests of urinary urea can be as reliable as urea from urine collected over longer periods.

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

AIM

Protein hydrolysates have been introduced in preterm formulae, but it is not clear whether they are needed for the feeding of preterm infants. We designed a randomized, controlled trial to test the effects of a preterm formula with hydrolysed cow's milk proteins on short-term growth and urinary and plasma amino acids levels.

METHODS

Infants with a birthweight < or = 1750 g and gestational age < or = 34 wk fed a conventional preterm infant formula (formula B) or a hydrolysed formula (formula A). Weight was measured daily; length, head circumference, mid-arm circumference and total skinfold thickness were measured weekly. Blood and urine were analysed for amino acid concentrations at start, 14 and 28 d.

RESULTS

Twenty-one infants met the criteria for randomization. The daily feeding volumes were: formula A 172.8 +/- 5.6 vs formula B 170.1 +/- 2.8 ml/kg/d. Infants fed with formula A showed slower weight gain (17.4 +/- 3.4 vs 20.5 +/- 3.3 g/kg/d; p = 0.045) and lower mean change in Z-scores for weight (-0.18 +/- 0.16 vs 0.00 +/- 0.09; p = 0.009) and for head circumference (-0.06 +/- 0.13 vs 0.06 +/- 0.13; p = 0.049). After 14 d, infants receiving formula A had statistically significant higher urinary levels of essential amino acids compared to infants receiving formula B.

CONCLUSION

Our results support the hypothesis of less nutritional value of hydrolysed versus conventional preterm formulae. Higher renal excretion of essential amino acids may be one of the mechanisms involved. These findings must be confirmed by further studies with larger sample sizes and protein hydrolysates with different degrees of hydrolysis.

Nutritional assessment and therapeutic interventions for the preterm infant

All components of assessment contribute to the final decision regarding nutritional status of the infant and the nutritional therapy indicated. One parameter by itself such as nutrient intake, weight change, or a laboratory value cannot clearly determine the total nutritional state of the infant. Achieving appropriate intakes and weight gains are two excellent parameters. Laboratory values can determine if nutrition is tolerated and manipulations are indicated.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

A fortifier comprising protein, vitamins, and calcium-glycerophosphate for preterm human milk

BACKGROUND

The infant's own mother's milk, fortified with proteins, minerals, and vitamins, is considered the best food for low-birth-weight infants. This paper describes the process to obtain a liquid human milk fortifier.

METHODS

The fortifier comprises a protein concentrate, calcium, phosphate, and zinc salts, as well as vitamins A and D. A powdered whey protein extracted from bovine milk was concentrated from 31.5-76.8 g/100 g using repetitive dialysis. The protein concentrate was dissolved in a 0.2 M phosphate buffer pH 7.4 and mixed with calcium-glycerophosphate and calcium-gluconate, vitamins A and D, folic acid, and zinc. Each 10 mL of this liquid fortifier has 0.78 g protein, 53 mg calcium, 36 mg phosphate, and 0.93 mg zinc.

RESULTS

Repetitive dialysis did not modify the protein structure as demonstrated by electrophoresis. A total of 95% of lactose content was discarded. Enriching human milk using this human milk fortifier increased the concentration per deciliter of all added nutrients; proteins increased from 1.68-2.35 g, calcium from 26-90 mg, and phosphorus, from 15-51 mg.

CONCLUSIONS

A liquid human milk fortifier was successfully manufactured using a noncomplex procedure. An intake of 180-200 mL/kg/day of the fortified human milk by the premature infant would satisfy the infant's nutritional requirements and achieve expected growth and development.

Human milk feeding of the micropremie

There is increasing evidence that mother's milk is an appropriate feeding even for LBW and VLBW infants. During early neonatal life, supplements in the form of human milk fortifiers or single nutrients may be necessary to maintain an adequate biochemical status especially for sodium, phosphorus, and protein. The ideal amount and balance of supplemental nutrients to add to mother's milk for small premature infants remain unknown. From research to date, it is clear that growth responses to fortified mother's milk fed in early life may not be the most important outcomes in relation to long-term growth and development. Infants who receive human milk in early life may be at reduced risk for developing infections and allergy as well as osteopenia and growth failure. Further studies are needed to provide a better understanding of the role of human milk as the sole source of nutrition in premature infants, especially the micropremie.

Protein supplementation of human milk for promoting growth in preterm infants

BACKGROUND

For term infants, human milk provides adequate nutrition to facilitate growth, as well as potential beneficial effects on immunity and the maternal-infant emotional state. However, the role of human milk in preterm infants is less well defined as it contains insufficient quantities of some nutrients to meet the estimated needs of the infant. Preterm infants require higher protein intakes than term infants to attain adequate growth rates, and have relatively higher protein turnover rates. Inadequate protein intakes may be partly responsible for low serum albumin and blood urea concentrations in preterm infants.

OBJECTIVES

The main objective was to determine if addition of protein to human milk leads to improved growth and neurodevelopmental outcomes without significant adverse effects in preterm infants.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. This includes searches of the Oxford Database of Perinatal Trials, MEDLINE, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, and journal handsearching mainly in the English language.

SELECTION CRITERIA

All trials utilizing random or quasi-random allocation to supplementation of human milk with protein or no supplementation in preterm infants who remained in hospital were eligible.

DATA COLLECTION AND ANALYSIS

Data were extracting using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by each author and synthesis of data using relative risk and weighted mean difference.

MAIN RESULTS

Protein supplementation of human milk results in increases in short term weight gain (WMD 3.6 g/kg/day, 95% CI 2.4 to 4.8 g/kg/day), linear growth (WMD 0.28 cm/week, 95% CI 0.18 to 0.38 cm/week) and head growth (WMD 0.15 cm/week, 95% CI 0.06 to 0.23 cm/week). There are insufficient data to evaluate long term neurodevelopmental and growth outcomes. There are too few infants studied to be certain that adverse effects of protein supplementation are not increased. Blood urea levels are increased (WMD 1.0 mmol/l, 95% CI 0.8 to 1.2 mmol/l).

REVIEWER'S CONCLUSIONS

Protein supplementation of human milk in relatively well preterm infants results in increases in short term weight gain, linear and head growth. Urea levels are increased, which may reflect adequate rather than excessive dietary protein intake. Further research should be directed towards the evaluation of specific levels of protein intake in preterm infants and the clinical effects of supplementation with protein, including long term growth and neurodevelopmental outcomes. This may best be done in the context of refinement of available multicomponent fortifier preparations.

Individualized protein fortification of human milk for preterm infants: comparison of ultrafiltrated human milk protein and a bovine whey fortifier

BACKGROUND

To improve the nutritional management of pre-term infants, a new individualized human milk fortification system based on presupplementation milk protein analyses was evaluated.

METHODS

In an open, prospective, randomized multicenter study, 32 healthy preterm infants (birth weights, 920-1750 g) were enrolled at a mean of 21 days of age (range, 9-36 days) when tolerating exclusive enteral feedings of 150 ml/kg per day. All infants were fed human milk and were randomly allocated to fortification with a bovine whey protein fortifier (n = 16) or ultrafiltrated human milk protein (n = 16). All human milk was analyzed for protein content before fortification with the goal of a daily protein intake of 3.5 g/kg. During the study period (mean, 24 days) daily aliquots of the fortified milk were obtained for subsequent analyses of the protein content.

RESULTS

Both fortifiers were well tolerated, and growth gain in weight, length, and head circumference, as well as final preprandial concentrations of serum urea, transthyretin, transferrin, and albumin were similar in both groups. The ultimate estimated protein intake was equivalent in both groups (mean 3.1+/-0.1 g/kg per day). Serum amino acid profiles were similar in both feeding groups, except for threonine (significantly higher in the bovine fortifier group) and proline and ornithine (significantly higher in the human milk protein group).

CONCLUSIONS

Protein analyses of the milk before individual fortification provides a new tool for an individualized feeding system of the preterm infant. The bovine whey protein fortifier attained biochemical and growth results similar to those found in infants fed human milk protein exclusively with the corresponding protein intakes.

Docosahexaenoic and arachidonic acid content of serum and red blood cell membrane phospholipids of preterm infants fed breast milk, standard formula or formula supplemented with n-3 and n-6 long-chain polyunsaturated fatty acids

The contents of docosahexaenoic (DHA) and arachidonic acid (AA) of plasma and red blood cell membrane phospholipids were studied in 41 very low birth weight infants fed either breast milk (n = 18), a standard formula without long-chain polyunsaturated fatty acids with 20 or 22 carbon atoms (LCP) but with alpha-linolenic acid and linoleic acid (n = 11) or a formula additionally supplemented with n-3 and n-6 LCP in relations typical for human milk (n = 12) after 2, 6, and 10 weeks of feeding. The content of DHA and AA in plasma phospholipids declined in the infants fed the LCP-free formula but remained more or less constant during the whole feeding period in those infants fed breast milk as well as in those fed the LCP-supplemented formula. The differences between the group fed the LCP-free standard formula and the two groups fed LCP-containing diets became significant during the first 2 weeks of feeding. In contrast, there were no differences between the group fed breast milk and the group fed the supplemented formula during the study period. Similar effects could be observed regarding the composition of red blood cell membrane phospholipids, but the differences between the infants fed the LCP-free standard formula and the two other groups with LCP-containing diets were significant only for AA. The data indicate that very low birth weight infants are unable to synthesize LCP from alpha-linolenic acid and linoleic acid in sufficient amounts to prevent a decline of LCP in plasma and red blood cell phospholipids. Additionally, the data show, that supplementation of formulas with n-3 and n-6 LCP in amounts typical for human milk fat results in similar fatty acid profiles of plasma and red blood cell membrane phospholipids as found during breast milk feeding.

CONCLUSION

Supplementation of formula with long-chain polyunsaturated fatty acids improves the LCP status of very low birth weight infants.