Short-term growth and substrate use in very-low-birth-weight infants fed formulas with different energy contents

Higher versus lower protein intake in formula-fed low birth weight infants

BACKGROUND

The ideal quantity of dietary protein for formula-fed low birth weight infants is still a matter of debate. Protein intake must be sufficient to achieve normal growth without leading to negative effects such as acidosis, uremia, and elevated levels of circulating amino acids.

OBJECTIVES

To determine whether higher (≥ 3.0 g/kg/d) versus lower (< 3.0 g/kg/d) protein intake during the initial hospital stay of formula-fed preterm infants or low birth weight infants (< 2.5 kilograms) results in improved growth and neurodevelopmental outcomes without evidence of short- or long-term morbidity. Specific objectives were to examine the following comparisons of interventions and to conduct subgroup analyses if possible. 1. Low protein intake if the amount was less than 3.0 g/kg/d. 2. High protein intake if the amount was equal to or greater than 3.0 g/kg/d but less than 4.0 g/kg/d. 3. Very high protein intake if the amount was equal to or greater than 4.0 g/kg/d.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 8), in the Cochrane Library (August 2, 2019); OVID MEDLINE Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily, and Ovid MEDLINE(R) (to August 2, 2019); MEDLINE via PubMed (to August 2, 2019) for the previous year; and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (to August 2, 2019). We also searched clinical trials databases and the reference lists of retrieved articles for randomized controlled trials (RCTs) and quasi-randomized trials.

SELECTION CRITERIA

We included RCTs contrasting levels of formula protein intake as low (< 3.0 g/kg/d), high (≥ 3.0 g/kg/d but < 4.0 g/kg/d), or very high (≥ 4.0 g/kg/d) in formula-fed hospitalized neonates weighing less than 2.5 kilograms. We excluded studies if infants received partial parenteral nutrition during the study period, or if infants were fed formula as a supplement to human milk.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane and the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We identified six eligible trials that enrolled 218 infants through searches updated to August 2, 2019. Five studies compared low (< 3 g/kg/d) versus high (3.0 to 4.0 g/kg/d) protein intake using formulas that kept other nutrients constant. The trials were small (n = 139), and almost all had methodological limitations; the most frequent uncertainty was about attrition. Low-certainty evidence suggests improved weight gain (mean difference [MD] 2.36 g/kg/d, 95% confidence interval [CI] 1.31 to 3.40) and higher nitrogen accretion in infants receiving formula with higher protein content (3.0 to 4.0 g/kg/d) versus lower protein content (< 3 g/kg/d), while other nutrients were kept constant. No significant differences were seen in rates of necrotizing enterocolitis, sepsis, or diarrhea. We are uncertain whether high versus low protein intake affects head growth (MD 0.37 cm/week, 95% CI 0.16 to 0.58; n = 18) and length gain (MD 0.16 cm/week, 95% CI -0.02 to 0.34; n = 48), but sample sizes were small for these comparisons. One study compared high (3.0 to 4.0 g/kg/d) versus very high (≥ 4 g/kg/d) protein intake (average intakes were 3.6 and 4.1 g/kg/d) during and after an initial hospital stay (n = 77). Moderate-certainty evidence shows no significant differences in weight gain or length gain to discharge, term, and 12 weeks corrected age from very high protein intake (4.1 versus 3.6 g/kg/d). Three of the 24 infants receiving very high protein intake developed uremia.

AUTHORS' CONCLUSIONS

Higher protein intake (≥ 3.0 g/kg/d but < 4.0 g/kg/d) from formula accelerates weight gain. However, limited information is available regarding the impact of higher formula protein intake on long-term outcomes such as neurodevelopment. Research is needed to investigate the safety and effectiveness of protein intake ≥ 4.0 g/kg/d.

Nutrition for Preterm Infants: 75 Years of History

As technology has advanced, survival rates of preterm infants have improved dramatically. Human milk was the primary source of enteral nutrition during the early days of neonatology, but the HIV/AIDS epidemic resulted in an increased use of preterm formula. More recently, the benefits of human milk were rediscovered, resulting in increased use of donor human milk as well. The awareness that human milk does not contain the amounts of nutrients to meet the high requirements of infants born premature resulted in the development of human milk fortifiers. The development of these fortifiers is still ongoing, as are alternative methods of pasteurization of donor milk. Those initiatives will increase the use of human milk with consequently short- and long-term benefits for preterm infants.

Protein use and weight-gain quality in very-low-birth-weight preterm infants fed human milk or formula

Background

Nutritional management of preterm infants aims to approximate the tissue growth and body composition of a fetus of the same postmenstrual age. The adequacy of the quality of protein supply can influence the rate and the relative quality of weight gain.

Objective

We investigated the protein balance according to feeding regimen and the association between human milk feeding and fat-free mass content at the term-corrected age in very-low-birth-weight preterm infants.

Design

A prospective observational study was conducted. Inclusion criteria were as follows: healthy infants, gestational age ≤32 wk, birth weight <1500 g, stable clinical conditions, and feeding by mouth with human milk or formula at discharge. Infants were enrolled at hospital discharge. At enrollment, macronutrient intakes and protein balance were determined. Anthropometric measurements and body composition were also assessed. The nutritional composition of human milk was calculated by infrared spectroscopy. The protein balance was determined according to the nitrogen balance standard method. Body composition was assessed by an air-displacement plethysmography system. At the term-corrected age, anthropometry and body composition assessments were repeated.

Results

Seventeen preterm infants fed fortified human milk and 15 preterm infants fed formula were enrolled. At discharge, despite similar macronutrient intakes, infants fed fortified human milk showed a higher nitrogen balance (expressed as mg · kg-1 · d-1) compared with preterm formula-fed infants (mean ± SD: 488.3 ± 75 compared with 409.8 ± 85 mg · kg-1 · d-1, P = 0.009). At term-corrected age, growth was similar in the 2 groups, whereas fortified human milk-fed infants showed a higher percentage of fat-free mass (85.1% ± 2.8% compared with 80.8% ± 3.2%, P = 0.002). Moreover, at multiple linear regression, fat-free mass content was independently associated with being fed human milk (R2 = 0.93, P < 0.0001).

Conclusion

Our findings suggest that human milk feeding is associated with early fat-free mass deposition in healthy and stable preterm infants. This trial was registered at www.clinicaltrials.gov as NCT03013374.

A new formula for premature infants: effects on growth and nutritional status

OBJECTIVE

Nutritional management influences immediate survival as well as subsequent growth and development of low birth weight and very low birth weight infants. Preterm infant formula (PTF) is used when there is an inadequate supply of mother's milk or when the mother is unable to breastfeed and donor breast milk is unavailable. The purpose of this prospective multicenter study was to evaluate short-term effects on nutritional status (auxological and biochemical parameters) in a population of premature infants who received a preterm infant formula.

METHODS

Ninety-seven preterm infants with a birth weight between 500 g and 2000 g and a gestational age of 25-34 weeks postmenstrual age were randomly assigned to received a new preterm infant formula (Nutribèn Pre), and their nutritional status were compared to 75 fortified human milk (FHM) fed infants.

RESULTS

No significant differences were observed between FHM and Nutribèn Pre fed infants in terms of growth, feeding tolerance and biochemical profiles.

CONCLUSION

Nutribèn Pre is a valid, effective and safe alternative for the nutrition of preterm infants.

Nutritional strategy of early amino acid administration in very low birth weight infants

Relative to a fetus of the same gestational age, very low birth weight (VLBW) infants are more likely to be underfed and to undergo growth restriction during their early hospital stay. The current trend towards "early and aggressive" nutritional strategies in VLBW infants aims to overcome the early nutritional deficiency and thereby boost postnatal catch-up growth, simultaneously improving long-term neurodevelopmental outcomes. Although the minimum starting amino acid (AA) dose to prevent negative nitrogen balance is well established, the upper limit and the rate of increase of early AA doses are controversial. Most randomized controlled trials show that early and high-dose (target, 3.5 to 4.9 g/kg/day) AA regimens, with or without high nonprotein calories, do not improve long-term growth and neurodevelopment. High-dose AA supplementation may lead to early metabolic disturbances and excessive or disproportionate plasma AA levels, particularly in infants of very low gestational age. Further large studies are needed to clarify the optimal strategy for early administration of parenteral AA doses in VLBW infants.

Lean mass and fat mass accretion between term age and 6 months post-term in growth-restricted preterm infants

Early growth restriction followed by nutritional intakes that permit accelerated growth may result in adiposity and metabolic disease in later life. This study compared growth, body composition and nutritional intake between term age and 6 months post-term in 83 appropriate-for-gestational-age preterm infants with growth restriction at term age (AGA GR+), 15 AGA without growth restriction at term age (AGA GR-) and 33 small-for-gestational-age (SGA) preterm infants. AGA GR+ and SGA preterm infants had higher protein intake, higher energy intake and higher gain in weight SDS between term age and 6 months post-term, with similar lean mass (LM) and lower fat mass (FM) at 6 months post-term compared with AGA GR- preterm infants. In conclusion, despite higher energy and protein intake compared with AGA GR- preterm infants during the first 6 months post-term, AGA GR+ and SGA preterm infants restore their LM without excessive FM.

A pediatrician's guide to caring for the complex neonatal intensive care unit graduate

Despite a decreasing trend in premature births, greater numbers of infants born at the limits of viability are surviving to discharge. Most of these infants have complex medical problems requiring multidisciplinary care. These infants are primarily cared for by the general pediatrician, but their needs are quite different from those of a full-term healthy newborn. The paucity of data regarding care for these infants complicates their management after hospital discharge. In this article, the authors present the most current evidence-based practices and provide a guide to the general pediatrician on caring for the complex neonatal intensive care unit graduate.

Linear growth and neurodevelopmental outcomes

Despite advances in care, preterm infants exhibit disproportionate growth and neurodevelopmental delay attributable to both nutritional and nonnutritional factors. These infants have prolonged linear stunting and decreased fat-free mass compared with their term counterparts. These 2 metrics index organ growth and development (including the brain) and protein accretion. Protein, along with carbohydrates, fats, and zinc, plays key roles in brain development, and deficiencies can lead to linear growth failure, abnormalities in the growth hormone axis, and developmental delay. Optimization of nutrition, including protein intake, decreasing inflammatory episodes, and enhancing the growth hormone axis will likely improve long-term outcomes.

High-protein formulas: evidence for use in preterm infants

Relatively high amounts of protein are required to achieve normal fractional protein synthetic rates during the late second through early third trimester of fetal growth. Once preterm infants achieve higher protein intakes for sustained periods, growth begins to approximate that of the normally growing fetus and long-term neurodevelopmental outcomes are improved. Preterm formulas have been developed that are enriched in protein. This review discusses several factors when using standard preterm formulas and high-protein preterm formulas in the neonatal intensive care unit, with an emphasis on quantity and quality of enteral protein delivery and risks to insufficient and/or excess protein administration.

Higher versus lower protein intake in formula-fed low birth weight infants

BACKGROUND

The ideal quantity of dietary protein for formula-fed low birth weight infants is still a matter of debate. Protein intake must be sufficient to achieve normal growth without negative effects such as acidosis, uremia, and elevated levels of circulating amino acids.

OBJECTIVES

To determine whether higher (≥ 3.0 g/kg/d) versus lower (< 3.0 g/kg/d) protein intake during the initial hospital stay of formula-fed preterm infants or low birth weight infants (< 2.5 kilograms) results in improved growth and neurodevelopmental outcomes without evidence of short- and long-term morbidity.To examine the following distinctions in protein intake. 1. Low protein intake if the amount was less than 3.0 g/kg/d. 2. High protein intake if the amount was equal to or greater than 3.0 g/kg/d but less than 4.0 g/kg/d. 3. Very high protein intake if the amount was equal to or greater than 4.0 g/kg/d.If the reviewed studies combined alterations of protein and energy, subgroup analyses were to be carried out for the planned categories of protein intake according to the following predefined energy intake categories. 1. Low energy intake: less than 105 kcal/kg/d. 2. Medium energy intake: greater than or equal to 105 kcal/kg/d and less than or equal to 135 kcal/kg/d. 3. High energy intake: greater than 135 kcal/kg/d.As the Ziegler-Fomon reference fetus estimates different protein requirements for infants based on birth weight, subgroup analyses were to be undertaken for the following birth weight categories. 1. < 800 grams. 2. 800 to 1199 grams. 3. 1200 to 1799 grams. 4. 1800 to 2499 grams.

SEARCH METHODS

The standard search methods of the Cochrane Neonatal Review Group were used. MEDLINE, CINAHL, PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library) were searched.

SELECTION CRITERIA

Randomized controlled trials contrasting levels of formula protein intake as low (< 3.0 g/kg/d), high (≥ 3.0 g/kg/d but < 4.0 g/kg/d), or very high (≥ 4.0 g/kg/d) in formula-fed hospitalized neonates weighing less than 2.5 kilograms were included. Studies were excluded if infants received partial parenteral nutrition during the study period or were fed formula as a supplement to human milk. Studies in which nutrients other than protein also varied were added in a post-facto analysis.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Neonatal Review Group were used.

MAIN RESULTS

Five studies compared low versus high protein intake. Improved weight gain and higher nitrogen accretion were demonstrated in infants receiving formula with higher protein content while other nutrients were kept constant. No significant differences were seen in rates of necrotizing enterocolitis, sepsis, or diarrhea.One study compared high versus very high protein intake during and after an initial hospital stay. Very high protein intake promoted improved gain in length at term, but differences did not remain significant at 12 weeks corrected age. Three of the 24 infants receiving very high protein intake developed uremia.A post-facto analysis revealed further improvement in all growth parameters in infants receiving formula with higher protein content. No significant difference in the concentration of plasma phenylalanine was noted between high and low protein intake groups. However, one study (Goldman 1969) documented a significantly increased incidence of low intelligence quotient (IQ) scores among infants of birth weight less than 1300 grams who received a very high protein intake (6 to 7.2 g/kg).

AUTHORS' CONCLUSIONS

Higher protein intake (≥ 3.0 g/kg/d but < 4.0 g/kg/d) from formula accelerates weight gain. However, limited information is available regarding the impact of higher formula protein intake on long-term outcomes such as neurodevelopmental abnormalities. Available evidence is not adequate to permit specific recommendations regarding the provision of very high protein intake (> 4.0 g/kg/d) from formula during the initial hospital stay or after discharge.

From parenteral to enteral nutrition: a nutrition-based approach for evaluating postnatal growth failure in preterm infants

BACKGROUND

Nutrition practices for preterm infants include phases of parenteral nutrition (PN), full enteral nutrition (EN), and the transitional phase in between. Our aim was to identify the nutrition phases during which infants are most likely to exhibit poor growth that would affect risk for growth failure (GF) at discharge and to examine factors associated with GF.

METHODS

A retrospective chart review was conducted on infants born <32 weeks' gestation. The neonatal intensive care unit stay was divided into 3 nutrition phases: (1) full PN, (2) transitional PN + EN, and (3) full EN. Weekly growth rates were calculated, and for each growth velocity <10 g/kg/d, the coinciding phase was recorded. GF was defined as a discharge weight below the 10th percentile. The nutrition phases during which growth inadequacy predicted GF at discharge were determined, correcting for other clinical factors associated with GF.

RESULTS

In total, 156 eligible infants were identified. Seventy-six infants (49%) were discharged with weights <10%. Incidence of poor growth was highest during the transitional phase (46%) and was predictive of GF when adjusted for gestational age, birth weight, and severity of illness. Although energy intakes during the transitional phase were comparable to baseline parenteral provision, protein intakes progressively decreased ( P < .0001), consistently providing 3 g/kg/d as PN was weaned. Serum urea nitrogen also declined and was correlated with protein intake (r = -0.32, P < .001).

CONCLUSION

Growth was compromised during the transitional phase, likely related to decreased protein intake. Optimizing protein provision while PN is weaned is an important strategy to prevent postnatal growth failure.

Neonatal management and safe discharge of late and moderate preterm infants

Late and moderate preterm infants form the majority of admissions for prematurity to special care neonatal nurseries. Although at risk for acute disorders of prematurity, they do not suffer the serious long term risks and chronic illnesses of the extremely premature. The special challenges addressed here are of transition and of thermal adaptation, nutritional compensation for postnatal growth restriction, the establishment of early feeding, and the avoidance of post-discharge jaundice or apnea. These 'healthy' premature infants provide challenges for discharge planning, in that opportunities may be available for discharge well before the expected date of delivery, which should be pursued. Barriers to early discharge are rigid conservative protocols and unwarranted investigations; facilitators of discharge are individualized care by nurses expert in cue-based feeding, early management of the thermal environment, support of family preferences and encouragement of mother-baby interactions. Safe discharge depends on recognizing these opportunities and applying strategies to address them.

Body composition in newborn infants: 5-year experience in an Italian neonatal intensive care unit

The aim of nutrition in neonatology is to achieve a healthy growth that mimics, both in terms of growth rates and quality of growth, that of a normal fetus of the same gestational age. In addition, providing an optimal amount and quality of nutrients significantly contributes to the attainment of a neurodevelopment similar to that of an infant born at term. Yet, a high risk of developing metabolic syndrome in relation to aggressive nutrition and accelerated postnatal growth velocity has been reported in former preterm infants. Considering the strict interrelationship that exists between early nutrition, growth, and subsequent health, the development of body composition in early infancy, in terms of fat mass, may contribute to the long-term "programming" process. Hence, accurate and non-invasive measurement of infant body composition, which evaluates the quality in addition to the amount of weight gain, represents a useful tool for gaining further insight into the relationship between birth weight or time in utero and future development. Preterm infants, including those born small for gestational age, have been reported to develop an increased and/or aberrant adiposity, in addition to postnatal growth retardation, when assessed at term-corrected age. However, within the first 5 months, preterm infants, either born adequate or small for gestational age, show a recovery of fat mass, and attain fat mass values comparable to those of full-term infants assessed at birth. The metabolic consequences of these findings on the long-term health need to be further clarified.

A longitudinal evaluation of growth outcomes at hospital discharge of very-low-birth-weight preterm infants

BACKGROUND/OBJECTIVES

To quantify the rate of progressive failure of very-low-birth-weight (VLBW) infants over time in the neonatal intensive care unit to meet growth milestones.

SUBJECTS/METHODS

In a prospective longitudinal study, 114 VLBW preterm infants (1500 g) of both sexes, with normal and/or low weight for gestational age were included. At the start, weight, length, mid-upper arm (MUAC), thigh and cephalic circumferences were measured. Weight/age (W/A), length/age and weight/length (±2 z-score) indices were calculated. All measurements were taken at inclusion, at 7, 15 and 30 days of hospitalization. Chi-square test, analysis of variance and repeated-measures tests were estimated.

RESULTS

Thirteen cases (14%) died and were excluded soon after the first determinations. In all, 9 (8.9%) died during the study, 12 (11.9%) were discharged before 30 days of life and 80 (79.2%) completed the study. At 7 days, the percentage of preterm infants with an index of W/A <-2 z-scores increased from 44 to 67% (44-68 subjects; P<0.01), with no changes afterwards; the indicator MUAC <-2 z-scores increased at 7 days from 23 to 49% (23-49 subjects); at 15 from 23 to 65% (23-61 subjects) and at 30 days from 23 to 79% (23-63 subjects; P<0.001).

CONCLUSIONS

Clinicians could use these indicators for earlier detection of growth failure in VLBW infants in order to target more aggressive nutrition early.

Rapid recovery of fat mass in small for gestational age preterm infants after term

Background

Preterm small for gestational age (SGA) infants may be at risk for increased adiposity, especially when experiencing rapid postnatal weight gain. Data on the dynamic features of body weight and fat mass (FM) gain that occurs early in life is scarce. We investigated the postnatal weight and FM gain during the first five months after term in a cohort of preterm infants.

Methodology/Principal Findings

Changes in growth parameters and FM were prospectively monitored in 195 infants with birth weight ≤1500 g. The infants were categorized as born adequate for gestational age (AGA) without growth retardation at term (GR−), born AGA with growth retardation at term (GR+), born SGA. Weight and FM were assessed by an air displacement plethysmography system. At five months, weight z-score was comparable between the AGA (GR+) and the AGA (GR−), whereas the SGA showed a significantly lower weight.The mean weight (g) differences (95% CI) between SGA and AGA (GR−) and between SGA and AGA (GR+) infants at 5 months were −613 (−1215; −12) and −573 (−1227; −79), respectively. At term, the AGA (GR+) and the SGA groups showed a significantly lower FM than the AGA (GR−) group. In the first three months, change in FM was comparable between the AGA (GR+) and the SGA groups and significantly higher than that of the AGA (GR−) group.The mean difference (95% CI) in FM change between SGA and AGA (GR−) and between AGA (GR+) and AGA (GR−) from term to 3 months were 38.6 (12; 65); and 37.7 (10; 65). At three months, the FM was similar in all groups.

Conclusions

Our data suggests that fetal growth pattern influences the potential to rapidly correct anthropometry whereas the restoration of fat stores takes place irrespective of birth weight. The metabolic consequences of these findings need to be elucidated.

Energy expenditure in very low birth weight newborns: a comparison between small and appropriate-for-gestational-age

AIMS

To compare resting energy expenditure (REE) in small- and appropriate-for-gestational-age very low birth weight newborns after reaching corrected at-term age.

METHODS

Observational study that included all clinically stable very low birth weight newborns admitted to a neonatal intensive care unit. The newborns were classified as small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA). Resting energy expenditure was measured using indirect calorimetry when the newborns reached at-term age.

RESULTS

A total of 51 newborns, of which 23 were SGA and 28 AGA, were included. There was no statistically significant difference in REE between the two groups, although the observed levels were higher than the reference values.

CONCLUSION

There is no statistical difference in resting expenditure energy between SGA and AGA infants when they reached term. The higher energy expenditure found in both groups may be explained by other factors related to prematurity and its complications and requires further investigation.

Enteral nutrient supply for preterm infants: commentary from the European Society of Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition

The number of surviving children born prematurely has increased substantially during the last 2 decades. The major goal of enteral nutrient supply to these infants is to achieve growth similar to foetal growth coupled with satisfactory functional development. The accumulation of knowledge since the previous guideline on nutrition of preterm infants from the Committee on Nutrition of the European Society of Paediatric Gastroenterology and Nutrition in 1987 has made a new guideline necessary. Thus, an ad hoc expert panel was convened by the Committee on Nutrition of the European Society of Paediatric Gastroenterology, Hepatology, and Nutrition in 2007 to make appropriate recommendations. The present guideline, of which the major recommendations are summarised here (for the full report, see http://links.lww.com/A1480), is consistent with, but not identical to, recent guidelines from the Life Sciences Research Office of the American Society for Nutritional Sciences published in 2002 and recommendations from the handbook Nutrition of the Preterm Infant. Scientific Basis and Practical Guidelines, 2nd ed, edited by Tsang et al, and published in 2005. The preferred food for premature infants is fortified human milk from the infant's own mother, or, alternatively, formula designed for premature infants. This guideline aims to provide proposed advisable ranges for nutrient intakes for stable-growing preterm infants up to a weight of approximately 1800 g, because most data are available for these infants. These recommendations are based on a considered review of available scientific reports on the subject, and on expert consensus for which the available scientific data are considered inadequate.

Caloric intake and weight gain in a neonatal intensive care unit

The aim of this paper was to study the weight gain in very-low-birthweight (VLBW) infants by adopting earlier and higher intake of proteins and earlier intake of lipids. We studied 28 VLBW infants admitted to Neonatal Intensive Care Unit during the year 2004 (group 1) and 18 during the first semester of 2006 (group 2). Dietary intakes for group 1 were: 1 g kg(-1) day(-1) of proteins started at postnatal day 2 (P2) and 0.5-1 g kg(-1) day(-1) of lipids at P3; for group 2, 1-1.5 g kg(-1) day(-1) of proteins and 0.5-1 g kg(-1) day(-1) of lipids, both started at P1. Caloric intake was significantly higher in group 2 (p < 0.05), whereas cumulative nutritional deficit was higher in group 1 (p < or = 0.01). Weight z scores were significantly lower at discharge comparing with z scores at birth for each group (p < or = 0.01), with no differences between the two groups. Despite a higher protein intake which resulted in a lower nutritional deficit, the weight z score did not improve significantly at discharge.

Is term newborn body composition being achieved postnatally in preterm infants?

BACKGROUND

The American Academy of Pediatrics (AAP) recommends that preterm infants' growth duplicates fetal growth rates and that body composition replicates in utero body composition.

AIMS

To compare the total body fat mass between preterm infants assessed at term corrected age and full-term newborns, and to investigate the effects of gestational age, gender, weight increase, being breast fed on total adiposity.

STUDY DESIGN

Prospective observational study.

SUBJECTS

One hundred and ten preterm infants [mean (SD) gestational age: 29.9 (2.3) weeks; birth weight: 1118 (274) g], and 87 full term [mean (SD) 38.6 (1.21) weeks, 3203 (385) g], breastfed infants.

OUTCOME MEASURES

Growth and body composition by means of a pediatric air displacement system were assessed at term corrected age in preterm infants and on day 3 of life in full term infants.

RESULTS

Weight, length and head circumference were smaller in the preterm group as compared to the term group. Mean (SD) percentage of fat mass in preterm infants was significantly higher as compared to term infants [14.8 (4.4) vs 8.59 (3.71), P<0.0001]. Fat mass was negatively correlated with gestational age (P<0.001), and positively associated with weight increase (P< 0.05).

CONCLUSIONS

Our data suggest that body composition, in terms of fat mass, in preterm infants at term corrected age is different from that of full term newborns.

Dynamic coordination of macronutrient balance during infant growth: insights from a mathematical model

BACKGROUND

Complex dynamic changes in body composition, dietary intake, energy expenditure, and macronutrient oxidation occur during infant growth. Although previous investigators have focused on energy requirements for normal growth, little is known about the dynamic coordination of macronutrient balance.

OBJECTIVE

Our objective was to develop a mathematical model of the dynamic relations between diet, macronutrient oxidation, and energy expenditure during normal infant growth.

DESIGN

We developed a mathematical model that integrates longitudinal data on changes of body composition and carbon dioxide production determined with the doubly labeled water method to calculate both energy intake requirements and macronutrient oxidation rates during normal infant growth.

RESULTS

The calculated fat oxidation rate was initially <20 kcal x kg(-1) x d(-1), despite the consumption of >60 kcal x kg(-1) x d(-1) of dietary fat. This discrepancy was maintained until approximately 6 mo, after which fat intake was only slightly greater than fat oxidation. Nonfat oxidation closely followed nonfat dietary intake for the duration of the period studied. Model calculations of the energy intake requirements for normal growth were slightly lower than previous estimates. The calculations were robust to variations of body weight, body composition, and diet composition input data, but depended sensitively on variations of carbon dioxide production data.

CONCLUSIONS

Our model presents a dynamic picture of how macronutrient oxidation adapts in concert with dietary changes and energy expenditure to give rise to normal tissue deposition. The model integrates a variety of data in a self-consistent way, simulating the complex metabolic adaptations occurring during normal growth while extracting important physiologic information from the data that would otherwise be unavailable.

Effect of enteral IGF-1 supplementation on feeding tolerance, growth, and gut permeability in enterally fed premature neonates

OBJECTIVES

The gastrointestinal tract of the premature newborn functions suboptimally with regard to digestion, absorption, and feeding tolerance. Human milk contains trophic factors, such as insulin-like growth factor-1 (IGF-1), that are believed to stimulate gut growth and function. The objective of this double blind, randomized, controlled trial was to assess the effects of enteral IGF-1 supplementation on whole body growth measured by weight gain (in grams per kilogram per day), days to regain birth weight, and anthropometrical characteristics, and gut maturation and permeability (measured by sugar absorption tests).

PATIENTS AND METHODS

The study included 60 premature infants (birth weight 750-1250 g) during the first month of life. Patients received either standard infant formula or standard infant formula supplemented with IGF-1 in a concentration twice that of human colostrum (10 microg/100 mL of formula). Primary endpoints were days to full enteral feeding, days to regain birth weight, and growth rate. Sugar absorption tests were performed weekly to assess the secondary endpoints gut permeability and maturation.

RESULTS

None of the primary endpoints differed to statistical significance between groups at any point. However, gut permeability was significantly lower in the IGF-1 supplement group on day 14 compared with the control group. At day 21, lactulose/mannitol excretion ratios were (again) comparable between the groups.

CONCLUSIONS

Although gut permeability showed a faster decrease in the IGF-1 supplement group, our data do not support IGF-1 supplementation to infant formula.

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.

Effect of high volume intake of mother's milk with an individualized supplementation of minerals and protein on early growth of preterm infants <28 weeks of gestation

OBJECTIVE

A prospective study was designed to evaluate the effects of high volume intake of mother's milk fortified (FMM) with an individualized supplementation of minerals and protein on tolerance, short-term somatic growth, serum concentrations of calcium, phosphorus, alkaline phosphatase, and total plasma protein in healthy preterm infants below 28 weeks of gestation.

METHODS

Sixty preterm infants were included in the FMM group, for having received >80% or more of the milk volume as their own mother's milk at 3 weeks of postnatal age to 38 weeks of corrected gestational age. This group was compared with 60 preterm infants fed exclusively preterm formula milk (PF). Intended fluid volume of the FMM group was approximately 200 and 150-170 mL/kg/d in the PF group. Mother's milk was supplemented with the goal of a daily protein intake of 3.5-4 g/kg/d. Phosphorus was supplemented from 15.5 to 31 mg per 100mL mother's milk.

RESULTS

Both feeding regimes were well tolerated. At the end of the study, nutritional management in both groups resulted in a body weight between the 25th and 50th percentiles of intrauterine growth expectations. Serum values of electrolytes, alkaline phosphatase, plasma protein, blood urea nitrogen, and urinary mineral excretion did not differ significantly between the two groups at study entry as well as at the end of the investigation.

CONCLUSIONS

Mother's milk fed at higher volumes with an individualized fortification of minerals and protein provides sufficient nutrients to allow adequate growth of preterm infants <28 weeks of gestation.

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.

Energy requirements

The determination of the appropriate energy and nutritional requirements of a newborn infant requires a clear goal of the energy and other compounds to be administered, valid methods to measure energy balance and body composition, and knowledge of the neonatal metabolic capacities. Providing an appropriate amount of energy to newborn infants remains a challenge considering the great number of newborn infants who suffer in-hospital growth retardation. The energy requirements of a newborn infant are influenced by several factors - basal metabolism, growth, energy expenditure, and energy losses - which change continuously during development. Calculating the energy requirements of preterm infants is subject to error if general recommendations are applied without recognition of the large variation in factors that influence, for example, energy expenditure. Therefore, energy recommendations should be individualized and preferably based on measurements of energy expenditure. In particular, extremely low birth-weight and very low birth-weight infants are prone to develop negative energy and nutrient balances, due to low energy intake, low energy reserves and high energy demands. Early energy accretion is not only essential for growth but also influences neurodevelopmental outcome and physical health in the long term, thereby underlining the importance of adequate neonatal nutrition.

Can extrauterine growth approximate intrauterine growth? Should it?

Most studies evaluating the growth of preterm infants use the so-called intrauterine growth curve and reference fetus as standards. These curves might not be the optimal standards, however, for several reasons. The curves were constructed from small numbers of infants with uncertainty about gestational age, reasons for preterm birth, and, for body-composition data, the reasons for the death of the infant. Second, preterm infants after birth are not comparable with fetuses, being in a completely different environment and receiving a completely different nutrition. For instance, a higher percentage of body fat in preterm infants might well be an adequate adaptation to their environment. To get preterm infants to adhere to their supposed growth curve percentile, catch-up growth is needed. Recent studies indicate that catch-up growth might be advantageous for brain development. It might at the same time increase the incidence of cardiovascular disease in later life. The use of intrauterine growth curves to evaluate postnatal growth needs a critical reevaluation.

Higher versus lower protein intake in formula-fed low birth weight infants

BACKGROUND

The ideal quantity of dietary protein for formula-fed low birth weight infants < 2.5 kilograms is still a matter of controversy and debate. In premature infants, the protein intake must be sufficient to achieve normal growth without negative effects such as acidosis, uremia, and elevated levels of circulating amino acids (e.g. phenylalanine levels). This systematic review evaluates the benefits and risks of higher (>= 3.0 g/kg/day) versus lower (< 3.0 g/kg/day) protein intakes during the initial hospital stay of formula-fed preterm infants < 2.5 kilograms.

OBJECTIVES

To determine whether higher (>= 3.0 g/kg/day) versus lower (< 3.0 g/kg/day) protein intakes during the initial hospital stay of formula-fed preterm infants < 2.5 kilograms result in improved growth and neurodevelopmental outcomes without evidence of short and long-term morbidity.

SEARCH STRATEGY

Two review authors searched MEDLINE (1966 - May 2005), CINAHL (1982 - May 2005), PubMed (1966 - May 2005), EMBASE (1980 - May 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2005), abstracts, conferences and symposia proceedings from Society of Pediatric Research, and American Academy of Pediatrics. Cross references were reviewed independently for additional relevant titles and abstracts for articles up to fifty years old.

SELECTION CRITERIA

Randomized controlled trials contrasting levels of formula protein intakes as low (< 3.0 g/kg/day), high (=> 3.0 g/kg/day but < 4.0 g/kg/day), or very high protein intake (=> 4.0 g/kg/day) during hospitalization of neonates less than 2.5 kilograms at birth who were formula-fed. Studies were not included if infants received partial parenteral nutrition during the study period or were fed formula as a supplement to human milk. Given the small number of studies that met all inclusion criteria, studies in which nutrients other than protein also varied (> 10% relative difference) were added in a post-facto analysis.

DATA COLLECTION AND ANALYSIS

Two review authors used standard methods of the Cochrane Collaboration and of the Cochrane Neonatal Review Group to independently assess trial eligibility and quality, and extracted data. In a 3-arm trial where two groups fell within the same predesignated protein intake group, weighted means and pooled standard deviations were calculated.

MAIN RESULTS

The literature search identified 37 studies, of which five met all the inclusion criteria. All five studies compared low (< 3.0 g/kg/day) to high protein intakes (=> 3.0 g/kg/day but < 4.0 g/kg/day). The overall analysis revealed an improved weight gain (WMD 2.36 g/kg/day, 95% CI 1.31, 3.40) and higher nitrogen accretion (WMD 143.7 mg/kg/day, 95% CI 128.7, 158.8) in infants receiving formula with higher protein content while other nutrients were kept constant. None of the studies reported IQ or Bayley scores at 18 months or later. No significant differences were seen in rates of necrotizing enterocolitis, sepsis or diarrhea. Of three studies included in the post-facto analysis, only one could be included in the meta-analysis. The post-facto analysis revealed further improvement in all growth parameters in infants receiving formula with higher protein content (weight gain: WMD 2.53 g/kg/day, 95% CI 1.62, 3.45, linear growth: WMD 0.16 cm/week, 95% CI 0.03, 0.30, and head growth: WMD 0.23, 95% CI 0.12, 0.35). There was no significant difference (WMD 0.25, 95% CI -0.20, 0.70) in the concentration of plasma phenylalanine between the high and low protein intake groups. One study (Goldman 1969) in the post-facto analysis documented a significantly increased incidence of low IQ scores, below 90, in infants of birth weight less than 1300 grams who received a very high protein intake (6 to 7.2 g/kg/day).

AUTHORS' CONCLUSIONS

This systematic review suggests that higher protein intake (=> 3.0 g/kg/day but < 4.0 g/kg/day) from formula accelerates weight gain. Based on increased nitrogen accretion rates, this most likely indicates an increase in lean body mass. Although accelerated weight gain is considered to be a positive effect, increase in other outcome measures examined may represent a negative or ambivalent effect. These include elevated blood urea nitrogen levels and increased metabolic acidosis. Limited information was available regarding the impact of higher formula protein intakes on long term outcomes such as neurodevelopmental abnormalities. As determined in this review, existing research literature on this topic is not adequate to make specific recommendations regarding the provision of very high protein intake (> 4.0 g/kg/day) from formula.

Extremely low birthweight infants: issues related to growth

While survival rates are increasing in the extremely low birthweight (ELBW) group of preterm infants, the most common morbidity among these infants is inadequate growth. By the time of discharge from the neonatal intensive care unit, many ELBW infants develop extrauterine growth restriction. Several issues related to improving the growth of ELBW infants, including defining adequate growth and developing evidence-based nutritional strategies, are discussed in this article. Suggestions for future research are also presented.

Malnutrition in critically ill children: from admission to 6 months after discharge

BACKGROUND & AIMS

Little is known about the nutritional status of critically ill children during hospitalisation in and after discharge from an intensive care unit. We set up a prospective, observational study to evaluate the nutritional status of children in an intensive care unit from admission up to 6 months after discharge. A secondary aim was identifying patient characteristics that influence the course of the various anthropometric parameters.

METHODS

The nutritional status of 293 children--104 preterm neonates, 96 term neonates and 93 older children--admitted to our multidisciplinary tertiary pediatric and neonatal intensive care unit was evaluated by anthropometry upon and during admission, at discharge and 6 weeks and 6 months following discharge.

RESULTS

Upon admission, 24% of all children appeared to be undernourished. Preterm and term neonates, but not older children, showed a decline in nutritional status during admission. At 6 months after discharge almost all children showed complete recovery of nutritional status. Length of stay and history of disease were the parameters that most adversely affected the nutritional status of preterm and term neonates at discharge and during follow-up.

CONCLUSION

While malnutrition is a major problem in pediatric intensive care units, most children have good long-term outcome in terms of nutritional status after discharge.

Splanchnic bed metabolism of glucose in preterm neonates

BACKGROUND

Glucose is a major oxidative substrate for intestinal energy generation in neonatal animals; however, few data in preterm infants are available. Early administration of enteral nutrition, including glucose, may be an effective strategy to support intestinal adaptation to extrauterine life in preterm neonates.

OBJECTIVE

The purpose of the present study was to quantify the first-pass uptake and oxidation of glucose by the splanchnic tissues (intestine and liver) in human neonates.

DESIGN

Eight preterm infants [birth weight ( +/- SD): 1.19 +/- 0.22 kg, gestational age: 29 +/- 1 wk] were studied while they received 2 different enteral intakes (A: 40% enteral, 60% parenteral, total glucose intake = 7.5 +/- 0.5 mg. kg(-1). min(-1), and B: 100% enteral, total glucose intake = 7.8 +/- 0.4 mg. kg(-1). min(-1)). Splanchnic and whole-body glucose kinetics were measured by use of dual-tracer techniques.

RESULTS

During both feeding periods, approximately one-third of dietary glucose intake was utilized during the first pass by the splanchnic tissues. More than three-quarters of this utilized glucose was oxidized in both periods (79 +/- 36% with A and 84 +/- 45% with B). Whole-body glucose oxidation was substantial under both circumstances: 72 +/- 5% and 77% +/- 6% of the glucose flux was oxidized during partial (A) and full (B) enteral feeding, respectively.

CONCLUSIONS

Approximately one-third of dietary glucose is utilized during the first pass by the splanchnic tissues, irrespective of the dietary intake. Most of the utilized glucose is used for energy generation.

Energy intake, metabolic balance and growth in preterm infants fed formulas with different nonprotein energy supplements

OBJECTIVE

To study metabolic and energy balances, growth and composition of increased body mass in healthy preterm infants fed control formula or control formula with three different nonprotein energy supplements.

PATIENTS AND METHODS

Growing preterm infants (birth weight < 1,500 g and gestational age < 31 weeks) were fed standard preterm formula (control group) or the same formula enriched with three different nonprotein energy supplements. An energy supplement of 23 kcal/kg/day was achieved by adding medium-chain triglyceride and dextrinomaltose in three different caloric ratios: 33:66 in group A, 66:33 in group B, and 85:15 in group C. Energy balance was determined by open-circuit continuous (5-6 hours) measurements of energy expenditure, with simultaneous measurement of 24-hour urinary nitrogen excretion. Metabolic balance was determined by measurements of energy intake, energy oxidation, and energy output in urine and stool. The composition of body mass accretion was determined as the accretion of fat and protein in the total weight gain.

RESULTS

The fat accretion (4.9, 5.9, 6.2, and 3.8 g/kg/day in groups A, B, C and D, respectively) correlated directly with fat intake. Infants receiving standard energy intake had a fat percentage of weight gain significantly lower (28%) than that of the high-energy intake groups (31%, 40%, and 38% in groups A, B, and C, respectively). This difference corresponded to the results obtained from skinfold thickness measurements.

CONCLUSIONS

Excess nonprotein energy is stored as fat regardless of its source (fat or carbohydrate). High caloric and medium-chain triglyceride intake in otherwise healthy growing preterm infants does not promote nitrogen retention.

Growth and body composition in preterm infants with bronchopulmonary dysplasia

OBJECTIVE

To compare growth and body composition in preterm infants with bronchopulmonary dysplasia (BPD) with normal healthy term infants during the first year of life.

DESIGN

Twenty nine preterm infants with BPD (mean (SD) gestational age 27.1 (1.6) weeks; birth weight 852 (173) g) were followed prospectively. Anthropometry and body composition determined by total body electrical conductivity were measured and compared with those of healthy term infants at the same post-term age.

RESULTS

In infants with BPD, the mean weight standard deviation scores (SD scores) 6 weeks after term were significantly lower (-1.44 and -2.68, boys and girls respectively) than in healthy term infants of the same age and did not improve during the first year. The mean length SD score was significantly lower in infants with BPD 6 weeks after term than in healthy term infants of the same age, and, although it improved significantly during the first year, the mean length SD score in girls with BPD was significantly below 0 12 months after term. In infants with BPD, the mean free fat mass (FFM) SD score and the mean total body fat (TBF) SD score at 6 weeks post-term age were significantly below 0. The mean FFM SD scores (-1.01 and -2.56, boys and girls respectively) and the mean TBF SD scores (-1.14 and -2.40, boys and girls respectively) 12 months after term were significantly lower than in healthy term infants of the same age.

CONCLUSIONS

Preterm infants with BPD have impaired growth, with a deficit in TBF and FFM already 6 weeks after term; FFM and TBF remain low compared with healthy term infants during the first year of life. Nutritional intervention studies in infants with BPD are needed to evaluate if nutrition is the major determinant of growth and body composition or if this pattern of growth in preterm infants with BPD is the result of disturbed endocrine control.

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.

Effects of quality of energy intake on growth and metabolic response of enterally fed low-birth-weight infants

Carbohydrate and fat may vary in their ability to support protein accretion and growth. If so, variations in the source of nonprotein energy might be used to therapeutic advantage in enterally fed low-birth-weight infants. To test the hypothesis that high-carbohydrate diets are more effective than isocaloric high-fat diets in promoting growth and protein accretion, low-birth-weight infants weighing 750-1600 g at birth were randomized in a double blind study to receive one of five formulas differing only in the quantity and quality of nonprotein energy. Groups 1, 2, and control received 130 kcal x kg(-1) x d(-1) with 35, 65, and 50% of the nonprotein energy as carbohydrate. Groups 3 and 4 received energy intake of 155 kcal x kg(-1) x d(-1) with 35 and 65% of the nonprotein energy as carbohydrate. Protein intake of all groups was 4 g x kg(-1) x d(-1). Growth and metabolic responses were followed weekly, and macronutrient balances including 6-h indirect calorimetry were performed biweekly. Greater rates of weight gain and nitrogen retention were observed at high-carbohydrate intake compared with high-fat intake at both gross energy intakes. Greater rates of energy storage and an increase in skinfold thickness were observed in group 4 (high-energy high-carbohydrate diet) despite higher rates of energy expenditure. These data support the hypothesis that at isocaloric intakes, carbohydrate is more effective than fat in enhancing growth and protein accretion in enterally fed low-birth-weight infants. However, a diet with high-energy and high-carbohydrate content also results in increased fat deposition.

Stability of respiratory quotient and growth outcomes of very low birth weight infants

Nutritional management of very low birth weight (VLBW) infants involves promoting growth at rates that mimic intrauterine rates. Nutritional intake at the recommended energy level to promote growth results in fat accretion at levels that exceed intrauterine rates for fat accretion. The respiratory quotient (RQ), the ratio of carbon dioxide produced to oxygen consumed during oxidation, provides a measure of the percentage of substrates used for energy. An RQ of greater than 0.9 indicates carbohydrate is used to meet energy needs, allowing the majority of fat intake to be stored as new tissue. The purpose of this study was to examine the stability of the RQ across time in relation to nutritional intake and growth in VLBW infants. Subjects were 9 enterally fed VLBW infants. Measurements to determine the RQ were obtained weekly for 3 weeks by indirect calorimetry. Nutritional intake and growth velocity were examined. There was no significant difference in the RQ across 3 weeks. The mean (+/- SD) RQs for each of the 3 weeks were 1.08 (+/- 0.04), 1.06 (+/- 0.05), and 1.06 (+/- 0.07), respectively. No significant differences were found across the 3 weeks for any of the macronutrient variables. Growth velocity for the period was 15.7 g/kg/day. By discharge from the NICU, 66% of the infants had weights less than the 10th percentile on an intrauterine growth reference. An RQ greater than 1.0 indicates VLBW infants are depositing excess fat. However, increased accretion rates of fat did not improve the growth outcomes of these VLBW infants.