Evaluation of body composition in neonates and infants

Reliability of routine anthropometric measurements to estimate body composition in term infants

BACKGROUND

Birth weight percentiles provide limited information on qualitative infant growth. Body composition provides estimates of fat mass, fat-free mass, and body fat percentage (adiposity). We sought to implement assessment of body composition at birth into clinical practice using a validated anthropometric equation and to evaluate measurement reliability.

METHODS

Body composition was incorporated into newborn nursery admission procedure. Body fat percentage derived from skinfold measurements performed by clinical nurses were compared to a historical database of similar measurements performed on newborns by experienced research staff. Body Mass Index (BMI) and Ponderal Index (PI) were used as surrogates for adiposity. Comparison of correlations between groups assessed measurement reliability. P < 0.05 was considered significant.

RESULTS

Nine hundred and ninety-one infants had body composition evaluated. Correlations were similar between BMI and %BF for measurements performed by research and clinical nurses (r² = 0.82 versus r² = 0.80; P = 0.142 for the difference between correlation coefficients) demonstrating good reliability. Similar results were found using PI (r² = 0.58 versus r² 0.53; P = 0.105).

CONCLUSIONS

Body composition can be assessed at birth using a validated anthropometric equation. Measurements performed by clinical RNs were found to be reliable, allowing for a qualitative measure of growth beyond birth weight.

IMPACT

Assessment of neonatal body composition at birth can be implemented into routine clinical practice using an anthropometric equation to estimate fat free-mass, fat mass, and percentage body fat. It provides a detailed, reproducible protocol to incorporate into routine practice. Assessment of fat mass, fat-free mass, and adiposity at birth allows for a qualitative measure of intrauterine growth beyond birth weight. Routine assessment of body composition provides a foundation for longitudinal follow-up of metabolic health in infancy and childhood.

D3-creatine dilution for the noninvasive measurement of skeletal muscle mass in premature infants

BACKGROUND

The rate of accrual of muscle mass in neonates has not been assessed. We describe the D₃-creatine (D₃Cr) dilution method, a noninvasive assessment of muscle mass in neonates.

METHODS

A total of 76 neonates >26-week-old corrected gestational age were enrolled and measured at 2-week intervals while admitted to a neonatal intensive care unit (NICU). Additional measures at 6 and 12-20 months after initial measurement were obtained if available. An enteral dose of 2 mg D₃Cr in 0.5 mL 20% ²H₂O was used to determine muscle mass and total body water (TBW).

RESULTS

Muscle mass by the D₃Cr method was strongly associated with TBW and body weight (r = 0.9272, p < 0.0001 and r = 0.9435, p < 0.0001 for all time points and r = 0.6661, p < 0.0001 and r = 0.8634, p < 0.0001, respectively, while in the NICU). Change in muscle mass vs. change in body weight, TBW, and length were also strongly correlated.

CONCLUSIONS

The D₃Cr dilution method provides a noninvasive assessment of muscle mass accrual in neonates, which has not been previously possible and may be an important new tool for the evaluation of nutritional status and normal growth patterns.

IMPACT

We describe a noninvasive method for the measurement of skeletal muscle mass neonates. At the present time, there is no direct measurement of muscle mass in infants available. The D₃Cr dilution method is a direct and noninvasive measurement of muscle mass. Using a single enteral dose of D₃Cr in ²H₂O followed by urine and saliva samples, rapid and substantial accrual of muscle mass and TBW is assessed. Assessment of muscle mass accrual in premature infants may be a strong indicator of nutritional status. Change in muscle mass is strongly related to change in weight and TBW.

Infant body composition assessment in the neonatal intensive care unit (NICU) using air displacement plethysmography: Strategies for implementation into clinical workflow

Nutritional management is integral to infant care in the neonatal intensive care unit (NICU). Recent research on body composition that specifically evaluated fat and fat-free mass has improved our understanding of infant growth and nutritional requirements. The need for body composition monitoring in infants is increasingly recognized as changes in fat mass and fat-free mass associated with early growth can impact clinical outcomes. With the availability of air displacement plethysmography (ADP) as a noninvasive method for assessing infant body composition and published normative gestational age- and sex-specific body composition curves, it is justifiable to integrate this innovation into routine clinical care. Here we describe our experiences in implementing body composition measurement using ADP in routine clinical care in different NICU settings.

Evaluation of anthropometric equations developed to estimate neonates' body composition: a systematic review

This article aims to evaluate the anthropometric equations developed by selected studies in order to estimate the body composition of neonates. The systematic review consisted in the research of published articles in the following databases: PubMed, Brazilian Virtual Health Library, Embase and ScienceDirect by utilizing the following descriptors: "fat mass, fat free mass, anthropometry, air displacement plethysmography, validation, neonate". For doing so, the PRISMA protocol has been utilized. The bibliographical research resulted in 181 articles. However, only eight were selected for the present review because repetition in different databases and having been performed in adults, during pregnancy, in athletes, in preterm and children. There was discrepancy in terms of study method, mainly over the variables of the anthropometric equations, age and ethnicity of the neonates. All studies used the plethysmography method as a reference apart from one study. Only four studies had their equations validated. The studies that developed anthropometric models for estimating the body composition of neonates are scarce, and the use of these equations needs to be conducted carefully in order to avoid errors in nutritional diagnosis.

Measuring fat mass in body equivalent materials using an RF resonant cavity

PURPOSE

Provide a proof of concept for the potential of using a novel RF resonant cavity device for accurately and repeatedly measuring fat and fat-free masses in phantom infants.

MATERIALS & METHODS

Design, construct, and characterize an RF resonant cavity with dimensions compatible to holding an infant. The cavity was characterized using spherical phantoms of 0%fat, 50% fat, and 100% fat to empirically calibrate shifts in resonant frequency. The phantoms were constructed using emulsions of bovine lard, water, and dish soap inside spherical containers which do not interact with the electric field. The calibration phantoms were compared with a phantom of a test sample to assess the ability of the resonant cavity perturbation technique for measuring body composition.

RESULTS

Phantoms of distinct %fat (0%, 50%, and 100%) were used to calibrate the resonant cavity for measuring body composition. The calibration phantoms were used to create calibration lines of unique %fat and were compared to a 475-mL sample of unknown %fat as a measure of how accurate the resonant cavity technique is for measuring body composition.

CONCLUSION

A 475 mL test sample was used to examine the robustness of the RCP technique. The sample was 25% fat and had a fat mass of ( 116.67 ± 0.96 ) g. The measured fat mass from the RCP technique was 114.30 ± 0.98  g, or a 2% difference. The resonant cavity perturbation technique provides an accurate and repeatable measurement of fat mass in spherical phantoms and suggests the technology might be an effective obesity research tool for infants. Future studies will focus on extending the work to more complex anthropomorphic shapes.

Normative Data for Lean Mass and Fat Mass in Healthy Predominantly Breast-Fed Term Infants From 1 Month to 1 Year of Age

BACKGROUND

A leaner body phenotype in infancy plays an important role in the early life prevention of obesity. However, there is a dearth of reference data for body composition in infancy. This study aimed to create a normative reference dataset for lean (LM) and fat (FM) mass and accretion rates in healthy infants.

METHODS

Healthy term-born infants (35 boys; 35 girls) were studied at ≤ 1, 3, 6, 9, and 12 mo of age for growth and compared to World Health Organization standards. LM (g) and FM (g) were measured using DXA (APEX version 13.3:3, Hologic 4500A) in infant whole-body mode. Sex specific reference curves were generated using the LMS method (LMSchartmaker, Medical Research Council, UK).

RESULTS

Infants were predominantly white (82.9%), breastfed (98.4% ≥ 3 mo), and grew in length and weight within World Health Organization Z-score ranges for normal growth across infancy. LM accretion was 327.4 ± 12.5 g/mo representing 95% increment in LM. Boys had more LM compared to girls at 12 mo (7807.4 ± 1114.0 vs 6817.4 ± 1016.1 g; p = 0.008). FM accretion was 114.3 ± 12.0 g/mo representing 114% increment in FM with no difference between the sexes.

CONCLUSIONS

This data, which is based on a healthy sample of infants, characterizes LM and FM accretion during the first year of life and will aid in the interpretation of body composition.

Factors affecting body composition in preterm infants: Assessment techniques and nutritional interventions

Limited research has been conducted that elucidates the growth and body composition of preterm infants. It is known that these infants do not necessarily achieve extra-utero growth rates and body composition similar to those of their term counterparts. Preterm infants, who have difficulty in achieving these growth rates, could suffer from growth failure. These infants display an increased intra-abdominal adiposity and abnormal body composition when they achieve catch-up growth. These factors affect the quality of weight gain, as these infants are not only shorter and lighter than term infants, they also have more fat mass (FM) and less fat-free mass (FFM), resulting in a higher total fat percentage. This could cause metabolic syndrome and cardiovascular problems to develop later in a preterm infant's life. The methods used to determine body composition in preterm infants should be simple, quick, non-invasive and inexpensive. Available literature was reviewed and the Dauncey anthropometric model, which includes skinfold thickness at two primary sites and nine body dimensions, is considered in this review the best method to accurately determine body composition in preterm infants, especially in resource-poor countries. It is imperative to accurately assess the quality of growth and body composition of this fragile population in order to determine whether currently prescribed nutritional interventions are beneficial to the overall nutritional status and quality of life-in the short- and long-term-of the preterm infant, and to enable timely implementation of appropriate interventions, if required.

Measuring body composition in the preterm infant: Evidence base and practicalities

Preterm birth and body composition have demonstrable effects on growth and later health outcomes. Preterm infants reach term equivalent age with a lower proportion of lean mass and higher body fat percentage than their term equivalent counterparts. Weight and length do not give an accurate assessment of body composition. Tracking body composition rather than just weight is a fundamental part of improving nutritional outcomes. This is important given the ongoing controversies regarding the nutritional needs of preterm infants, as well as establishing suitable targets for their growth. In this review we describe current methodologies used in the measurement of body composition of the preterm infant and the review the recent published evidence for their accuracy and utility. Current measurement techniques employed include air displacement plethysmography, bioelectrical impedance analysis, isotope dilution techniques, MRI and a combination of manual measurements including skinfold thickness, body mass index and mid upper arm/mid-thigh circumference. These measures allow for the estimation of fat mass, fat-free mass and regional assessment of adiposity. Some methods, such as dual-energy X-ray absorptiometry and air displacement plethysmography do allow for comparison of change in body composition over time in cohorts of preterm infants that may be studied over a longer period of time and into adult life. However, none of the currently described methods give an accurate and practically achievable method of obtaining body composition measures in preterm infants in day to day routine clinical practise, although this remains a key priority when decisions are being made about how best to feed.

An anthropometric approach to characterising neonatal morbidity and body composition, using air displacement plethysmography as a criterion method

Background

With the greatest burden of infant undernutrition and morbidity in low and middle income countries (LMICs), there is a need for suitable approaches to monitor infants in a simple, low-cost and effective manner. Anthropometry continues to play a major role in characterising growth and nutritional status.

Methods

We developed a range of models to aid in identifying neonates at risk of malnutrition. We first adopted a logistic regression approach to screen for a composite neonatal morbidity, low and high body fat (BF%) infants. We then developed linear regression models for the estimation of neonatal fat mass as an assessment of body composition and nutritional status.

Results

We fitted logistic regression models combining up to four anthropometric variables to predict composite morbidity and low and high BF% neonates. The greatest area under receiver-operator characteristic curves (AUC with 95% confidence intervals (CI)) for identifying composite morbidity was 0.740 (0.63, 0.85), resulting from the combination of birthweight, length, chest and mid-thigh circumferences. The AUCs (95% CI) for identifying low and high BF% were 0.827 (0.78, 0.88) and 0.834 (0.79, 0.88), respectively.

For identifying composite morbidity, BF% as measured via air displacement plethysmography showed strong predictive ability (AUC 0.786 (0.70, 0.88)), while birthweight percentiles had a lower AUC (0.695 (0.57, 0.82)). Birthweight percentiles could also identify low and high BF% neonates with AUCs of 0.792 (0.74, 0.85) and 0.834 (0.79, 0.88). We applied a sex-specific approach to anthropometric estimation of neonatal fat mass, demonstrating the influence of the testing sample size on the final model performance.

Conclusions

These models display potential for further development and evaluation in LMICs to detect infants in need of further nutritional management, especially where traditional methods of risk management such as birthweight for gestational age percentiles may be variable or non-existent, or unable to detect appropriately grown, low fat newborns.

Validity of anthropometric equations to estimate infant fat mass at birth and in early infancy

BACKGROUND

In newborns and children, body fat estimation equations are often used at different ages than the age used to develop the equations. Limited validation studies exist for newborn body fat estimation equations at birth or later in infancy. The study purpose was to validate 4 newborn fat mass (FM) estimation equations in comparison to FM measured by air displacement plethysmography (ADP; the Pea Pod) at birth and 3 months.

METHODS

Ninety-five newborns (1-3 days) had their body composition measured by ADP and anthropometrics assessed by skinfolds. Sixty-three infants had repeat measures taken (3 months). FM measured by ADP was compared to FM from the skinfold estimation equations (Deierlein, Catalano, Lingwood, and Aris). Paired t-tests assessed mean differences, linear regression assessed accuracy, precision was assessed by R² and standard error of the estimate (SEE), and bias was assessed by Bland-Altman plots.

RESULTS

At birth, FM measured by ADP differed from FM estimated by Deierlein, Lingwood and Aris equations, but did not differ from the Catalano equation. At 3 months, FM measured by ADP was different from all equations. At both time points, poor precision and accuracy was detected. Bias was detected in most all equations.

CONCLUSIONS

Poor agreement, precision, and accuracy were found between prediction equations and the criterion at birth and 3 months.

Bioelectrical Impedance of Vectorial Analysis and Phase Angle in Adolescents

OBJECTIVES

Bioelectrical impedance can be interpreted by vector analysis using direct measures of the impedance vector; thus, collecting information about resistance (R), reactance (Xc), and phase angle (PA) makes it possible to classify an individual's nutritional status. The aim of this study was to investigate these values and construct bioelectrical references for healthy Brazilian adolescents.

METHODS

This is a cross-sectional study that included 567 healthy adolescents, aged 10 to 18 years. The bioelectrical impedance was performed to collect data for R and Xc. In addition, weight and height were also collected. The PA was calculated, and thereby the tolerance and confidence ellipses were constructed using specific software.

RESULTS

For boys the mean vectors of 11 and 12 years, 12 and 13 years, 13 and 14 years, and 15 and 16 years were different from each other (p < 0.05). For girls the only mean vectors with significant differences were 11 and 12 years (p = 0.0071). The results differ from those in the literature, possibly due to ethnic differences in body composition.

CONCLUSION

The present study provides an important tool for monitoring the nutritional status of adolescents of different ages, without previous knowledge of some anthropometric measures such as body weight.

Feasibility study: Assessing the influence of macronutrient intakes on preterm body composition, using air displacement plethysmography

AIM

Preterm nutrition guidelines target nutrient accretion and growth at intrauterine rates, yet at term equivalent age, the phenotype of the preterm infant differs from that of term infants. Monitoring early changes in preterm body composition (BC) in response to macronutrient intakes may facilitate our understanding of how best to meet preterm nutrition and growth targets.

METHOD

Macronutrient intakes based on milk analysis were calculated from birth for infants born <33 weeks gestation. BC was measured in the PEA POD when infants were thermodynamically stable, free of intravenous lines and independent of respiratory support. Subsequent BC measurements were taken at least fortnightly until term age. Regression analysis was used to assess macronutrient influences on changes in BC.

RESULTS

Median (range) gestation and birthweight of preterm infants (n = 27) were 29 (25-32) weeks and 1395 (560-2148) g, respectively. The youngest corrected gestational and postnatal ages that infants qualified for a PEA POD measurement were 31.86 and 1.43 weeks, respectively. Fat and total energy intakes were positively associated with increasing fat mass. Protein (with carbohydrate) intake was positively associated with increasing fat-free mass.

CONCLUSION

Preterm infants can be measured in the PEA POD as early as 31 weeks corrected gestational age and the method appears sufficiently sensitive to detect influences of macronutrient intake on changes in BC.

Body composition assessment in the infant

Body composition assessment provides a sharper picture of the human biological response to genetic and environmental influences than measures of body size and weight. Infant body composition is particularly important as a marker of fetal adaptation and developmental programming of subsequent health and disease, but until recently, the range of options for measuring infant body composition was relatively narrow. The purpose of this Toolkit: Methods in Human Biology review is to provide a comprehensive overview of methods of body composition methods currently used in infants 0 to 2 years of age, including anthropometric prediction equations, air displacement plethysmography (ADP), dual energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), isotope dilution, and magnetic resonance imaging (MRI). Information on the reliability, validity, and accuracy of the methods is provided. Unique aspects of infant physiology and behavior create challenges for body composition assessment, but this review provides guidance on suitable testing approaches and environments that may aid researchers in this important area of investigation.

Breastfeeding and neonatal weight loss in healthy term infants

BACKGROUND

Neonatal weight loss is universally recognized, yet poorly understood. Limited professional consensus exists on the definition of lower limit of safe weight loss.

OBJECTIVE

Our aim was to assess the extent of neonatal weight loss and its association with selected clinical variables in a population of healthy term infants cared for using a specific protocol on weight loss.

METHODS

We retrospectively considered 1003 infants consecutively admitted to the regular nursery of the Institute for Maternal and Child Health "Burlo Garofolo" (Trieste, Italy). We studied the relationship of selected variables with neonatal weight loss recorded during the hospital stay. We also analyzed all readmissions in the first month of life as a result of weight loss and its complications.

RESULTS

We observed a mean absolute weight loss of 228 g ± 83g, and a mean percent weight loss of 6.7% ± 2.2%. Weight loss ≥ 10% and > 12% were 6% and 0.3%, respectively. In multivariate logistic regression, cesarean section, hot season, any formula feeding, and jaundice not requiring phototherapy were independently associated with neonatal weight loss ≥ 8%. Conversely, low gestational age status was associated with lower weight loss. Readmission within the first month of life because of dehydration occurred in 0.3% of infants.

CONCLUSIONS

Breastfeeding, compared to formula feeding, may not be a risk factor for greater early neonatal weight loss, at least in contexts in which weight is routinely monitored, breastfeeding is repeatedly assessed and appropriately supported, and careful supplementation is prescribed to limit and promptly treat excess weight loss and its related complications.

Preterm birth and body composition at term equivalent age: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Infants born preterm are significantly lighter and shorter on reaching term equivalent age (TEA) than are those born at term, but the relation with body composition is less clear. We conducted a systematic review to assess the body composition at TEA of infants born preterm.

METHODS

The databases MEDLINE, Embase, CINAHL, HMIC, "Web of Science," and "CSA Conference Papers Index" were searched between 1947 and June 2011, with selective citation and reference searching. Included studies had to have directly compared measures of body composition at TEA in preterm infants and infants born full-term. Data on body composition, anthropometry, and birth details were extracted from each article.

RESULTS

Eight studies (733 infants) fulfilled the inclusion criteria. Mean gestational age and weight at birth were 30.0 weeks and 1.18 kg in the preterm group and 39.6 weeks and 3.41 kg in the term group, respectively. Meta-analysis showed that the preterm infants had a greater percentage total body fat at TEA than those born full-term (mean difference, 3%; P = .03), less fat mass (mean difference, 50 g; P = .03), and much less fat-free mass (mean difference, 460 g; P < .0001).

CONCLUSIONS

The body composition at TEA of infants born preterm is different than that of infants born at term. Preterm infants have less lean tissue but more similar fat mass. There is a need to determine whether improved nutritional management can enhance lean tissue acquisition, which indicates a need for measures of body composition in addition to routine anthropometry.

Air-displacement plethysmography for determining body composition in neonates: validation using live piglets

INTRODUCTION

Air-displacement plethysmography (ADP) was developed as a noninvasive tool to assess body composition, i.e., the proportion of fat mass (%FM) and lean body mass. The results of previous studies comparing ADP with labeled water dilution in infants and with chemical analysis in phantoms have validated the ADP approach indirectly. We assessed the precision and accuracy of measurements of % FM proportions in live animals, using ADP in comparison with biochemical analyses.

METHODS

Three groups of 12 piglets each underwent four consecutive body composition assessments at 2, 7, and 21 d and were euthanized to determine whole-body lipid content by direct chemical analysis.

RESULTS

The average body weights were 1,490, 2,210, and 5,610 g at d2, d7, and d21, respectively. The mean %FM values determined by biochemical analysis and ADP were 8.63 ± 4.08% and 8.01 ± 4.03%, respectively. Linear regression and Bland-Altman analyses indicated good agreement for %FM. The root mean square coefficient of variation (RMS-CV) for ADP was 17.9%, with a better precision in the higher fat mass range.

DISCUSSION

Despite its relatively poor precision in the low range of %FM, ADP measures fat mass with reasonable precision and accuracy in the range of body weight encountered in low-birth-weight infants.

An anthropometric model to estimate neonatal fat mass using air displacement plethysmography

BACKGROUND

Current validated neonatal body composition methods are limited/impractical for use outside of a clinical setting because they are labor intensive, time consuming, and require expensive equipment. The purpose of this study was to develop an anthropometric model to estimate neonatal fat mass (kg) using an air displacement plethysmography (PEA POD® Infant Body Composition System) as the criterion.

METHODS

A total of 128 healthy term infants, 60 females and 68 males, from a multiethnic cohort were included in the analyses. Gender, race/ethnicity, gestational age, age (in days), anthropometric measurements of weight, length, abdominal circumference, skin-fold thicknesses (triceps, biceps, sub scapular, and thigh), and body composition by PEA POD® were collected within 1-3 days of birth. Backward stepwise linear regression was used to determine the model that best predicted neonatal fat mass.

RESULTS

The statistical model that best predicted neonatal fat mass (kg) was: -0.012 -0.064*gender + 0.024*day of measurement post-delivery -0.150*weight (kg) + 0.055*weight (kg)2 + 0.046*ethnicity + 0.020*sum of three skin-fold thicknesses (triceps, sub scapular, and thigh); R2 = 0.81, MSE = 0.08 kg.

CONCLUSIONS

Our anthropometric model explained 81% of the variance in neonatal fat mass. Future studies with a greater variety of neonatal anthropometric measurements may provide equations that explain more of the variance.

Effect of breastfeeding compared with formula feeding on infant body composition: a systematic review and meta-analysis

BACKGROUND

Early-life nutrition may influence later body composition. The effect of breastfeeding and formula feeding on infant body composition is uncertain.

OBJECTIVE

We conducted a systematic review and meta-analysis of studies that examined body composition in healthy, term infants in relation to breastfeeding or formula feeding.

DESIGN

PubMed was searched for human studies that reported the outcomes fat-free mass, fat mass, or the percentage of fat mass in breastfed and formula-fed infants. Bibliographies were hand searched, and authors were contacted for additional data. The quality of studies was assessed. Differences in outcomes between feeding groups were compared at prespecified ages by using fixed-effects analyses except when heterogeneity indicated the use of random-effects analyses.

RESULTS

We identified 15 studies for inclusion in the systematic review and 11 studies for inclusion in the meta-analysis. In formula-fed infants, fat-free mass was higher at 3-4 mo [mean difference (95% CI): 0.13 kg (0.03, 0.23 kg)], 8-9 mo [0.29 kg (0.09, 0.49 kg)], and 12 mo [0.30 kg (0.13, 0.48 kg)], and fat mass was lower at 3-4 mo [-0.09 kg (-0.18, -0.01 kg)] and 6 mo [-0.18 kg (-0.34, -0.01 kg)] than in breastfed infants. Conversely, at 12 mo, fat mass was higher in formula-fed infants [0.29 kg (-0.03, 0.61 kg)] than in breastfed infants.

CONCLUSION

Compared with breastfeeding, formula feeding is associated with altered body composition in infancy.

Prediction of fat-free mass and percentage of body fat in neonates using bioelectrical impedance analysis and anthropometric measures: validation against the PEA POD

Accurate assessment of neonatal body composition is essential to studies investigating neonatal nutrition or developmental origins of obesity. Bioelectrical impedance analysis or bioimpedance analysis is inexpensive, non-invasive and portable, and is widely used in adults for the assessment of body composition. There are currently no prediction algorithms using bioimpedance analysis in neonates that have been directly validated against measurements of fat-free mass (FFM). The aim of the study was to evaluate the use of bioimpedance analysis for the estimation of FFM and percentage of body fat over the first 4 months of life in healthy infants born at term, and to compare these with estimations based on anthropometric measurements (weight and length) and with skinfolds. The present study was an observational study in seventy-seven infants. Body fat content of infants was assessed at birth, 6 weeks, 3 and 4·5 months of age by air displacement plethysmography, using the PEA POD body composition system. Bioimpedance analysis was performed at the same time and the data were used to develop and test prediction equations for FFM. The combination of weight+sex+length predicted FFM, with a bias of < 100 g and limits of agreement of 6–13 %. Before 3 months of age, bioimpedance analysis did not improve the prediction of FFM or body fat. At 3 and 4·5 months, the inclusion of impedance in prediction algorithms resulted in small improvements in prediction of FFM, reducing the bias to < 50 g and limits of agreement to < 9 %. Skinfold measurements performed poorly at all ages.

Mechanical-tactile stimulation (MTS) during neonatal stress prevents hyperinsulinemia despite stress-induced adiposity in weanling rat pups

Stress in early life negatively influences growth quality through perturbations in body composition including increased fat mass. At term (40 weeks) preterm infants have greater fat mass and abdominal visceral adipose tissue than term-born infants. Mechanical-tactile stimulation (MTS) attenuates the stress response in preterm infants and rodents. We tested the hypothesis that MTS, administered during an established model of neonatal stress, would decrease stress-driven adiposity and prevent associated metabolic imbalances in rat pups. Pups received one of three treatments from postnatal days 5 to P9: Neonatal Stress (Stress; n=20) = painful stimulus and hypoxic/hyperoxic challenge during 60 min of maternal separation; MTS (n=20) = neonatal stress+10 min of MTS; or Control (n=20). Body weight, DXA whole body fat mass (g), MRI subcutaneous and visceral adipose tissue, and fasting adiponectin, leptin, glucose, insulin, and corticosterone were measured at weaning (P21). Stress and MTS weight gain (g/d) were accelerated following neonatal stress with greater fat mass, abdominal subcutaneous adipose tissue, serum adiponectin, leptin, and fasting glucose at weaning (P21). Male Stress and MTS pups had greater visceral adipose tissue depot. Male and female Stress pups were hyperinsulinemic. In summary, neonatal stress compromised body composition by increasing fat mass and abdominal subcutaneous adipose tissue depot, and in males, visceral adipose tissue depot. Importantly, MTS prevented hyperinsulinemia despite of stress-induced adiposity. We conclude that MTS during neonatal stress has the potential to minimize metabolic consequences associated with stress-driven perturbations in fat mass and abdominal adipose depots.

Quality of growth in exclusively breast-fed infants in the first six months of life: an Italian study

Nutrition in early life, growth, and subsequent health over a lifetime are significantly interrelated. The aim of this study was to assess body composition changes in exclusively breast-fed infants from birth up to 6 mo of age. An observational, prospective, cohort study was conducted. Fifty-nine full-term, healthy, exclusively breast-fed infants underwent assessment of growth and body composition, using air-displacement plethysmograph (i.e. PEA POD) by Life Measurement, Inc. (Concord, CA). Body composition was assessed at birth, 2 wk, and 1, 2, 3, 4, 5, and 6 mo of age. Mean birth weight (g) and gestational age (wk) of the infants were 3170 ± 420 and 39.21 ± 1.29, respectively. Percentage of fat mass increased significantly over the first 4 mo (p < 0.001), both in boys and girls, with no differences detected between boys and girls at any time point. This article provides preliminary in-depth data on whole-body composition, in exclusively breast-fed infants during the first months of life. Further studies assessing larger sample sizes are desirable to develop reference body composition data.

Deuterium equilibrium time in saliva of newborn infants

There is an increasing interest about the use of stable isotopes for body composition analysis in pediatrics. To ensure the success of total body water analysis by the deuterium dilution method, it is fundamental to determine the equilibrium time (plateau) of deuterium in the body fluid studied.

OBJECTIVES

We report here the equilibration time of deuterium oxide in the saliva of newborns after oral intake of the isotope.

METHODS

Twenty healthy term newborn infants, 10 males and 10 females, were analyzed. Saliva was collected from each newborn before the oral administration of a 100 mg/kg dose of deuterium oxide (baseline sample) and then at 1-hour intervals for 5 hours after administration. Deuterium enrichment of saliva was determined by isotope ratio mass spectrometry according to the recommendations of the International Atomic Energy Agency.

RESULTS

The plateau time of deuterium in saliva occurred 3 hours after oral administration of the stable isotope.

CONCLUSION

These data are essential for further studies on the body composition of newborn infants. To the best of our knowledge, this is the first study regarding the equilibration time of deuterium in the saliva of term newborns.

Measuring the body composition of preterm and term neonates: from research to clinical applications

Assessment of body and weight gain composition is one of the major keys for the evaluation of nutritional requirements in preterm and term infants. The changes in body composition during the first years of life seem to play an important role in the nutritional programming of adult morbidity. Noninvasive and indirect techniques are the most suitable methods for measuring body composition in preterm and term infants. Most of these techniques are used in clinical practice, whereas others are used mainly for research.

Preventing postnatal growth failure--the significance of feeding when the preterm infant is clinically stable

Nutrition guidelines and growth targets for preterm infants are currently based upon the reference standard of intrauterine growth and fetal nutrient accretion rates. This may not be an entirely appropriate standard--it is rarely achieved in clinical practice. Postnatal growth failure of very preterm infants is a universal problem with potentially significant, adverse neurological and health outcomes. The nutrient deficit that accumulates in the early weeks postdelivery when the preterm infant is clinically unstable is difficult to recover. Weight, length and head circumference measurements remain important clinical indicators of growth but composition of weight gain is emerging as a necessary measure in determining the adequacy of nutrition intake and growth. Recommended protein and energy intakes for very preterm infants are difficult to achieve with commercial human milk fortifiers and during hospitalisation, targeting the fortification of human milk to optimise the protein to energy ratio of milk feeds is necessary to ensure appropriate composition of weight gain. Postdischarge, continued fortification of human milk feeds may be required for a limited period of time for preterm infants with suboptimal weight for corrected age.

AIM AND METHODS

The following systematic review is aimed to derive evidence-based best practice guidelines for prevention of postnatal growth failure of very preterm infants who are clinically stable and growing. The focus is on reviewing the standard upon which ideal growth and nutrition guidelines are based and targeting fortification to maximise the protein to energy ratio in human milk feeds to ensure appropriate composition of weight gain. Directions for future research are provided. For the literature review the data bases Medline, EMBASE, CINAHL, the Cochrane Library and reference lists of review articles were reviewed to December 2006. A hand search of paediatric and perinatal journals was also conducted.

Measuring in vivo intracellular protein degradation rates in animal systems

Continual synthesis and breakdown or remodeling of proteins (also called protein turnover) is a principal characteristic of protein metabolism. During animal production, the net differences between synthesis and breakdown represent the actual marketable muscle foods. Because protein synthesis is a highly end-ergonic and protein breakdown is metabolic energy dependent, efficiency of production can be markedly enhanced by lower muscle protein breakdown rates. Herein, various methodological approaches to studying protein breakdown, with particular emphasis toward food-producing animals, are presented. These include whole-animal tracer AA infusions in vivo, quantifying marker AA release from muscle proteins, and in vitro AA release-based methodologies. From such methods, protein synthesis rates and protein breakdown rates (mass units/time) may be obtained. The applications of such methods and innovations based on traditional methods are discussed. Whole-animal in vivo approaches are resource intensive and often not easily applied to high-throughput metabolic screening. Over the last 25 yr, biochemical mechanisms and molecular regulation of protein biosynthesis and protein breakdown have been extensively documented. Proteolysis is dependent in part on the extent of expression of genes for components of cellular proteolytic machinery during skeletal muscle atrophy. It is proposed that high-throughput methods, based on emerging understanding about protein breakdown, may be useful in enhancing production efficiency.

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.