Adiposity in small for gestational age preterm infants assessed at term equivalent age

Inflammation induces stunting by lowering bone mass via GH/IGF-1 inhibition in very preterm infants

BACKGROUND

Sustained systemic inflammatory response (SIR) was associated with poor postnatal growth in very preterm infants (VPI). We hypothesize that VPI with sustained SIR will exhibit linear growth retardation related to lower bone mass accrual mediated by GH/IGF-1 axis inhibition at term corrected age (CA).

METHODS

C-reactive protein (CRP), procalcitonin (PCT), growth hormone (GH), insulin-like growth factor 1 (IGF-1), calcium, phosphorus, alkaline phosphatase, anthropometric, nutritional, neonatal and maternal data were collected prospectively in 23 infants <32 weeks gestational age. Body composition using dual-energy X-ray absorptiometry was performed at term CA. Analysis was undertaken with multiple linear regression models.

RESULTS

At term CA 11 infants with sustained SIR compared with 12 infants without sustained SIR present significantly lower IGF-1, length z-score (LZS), bone mineral content (BMC) and lean mass (LM), and higher GH and fat mass (FM). LZS was associated significantly with PCT, BMC with IGF-1, FM and LM with CRP, GH with bronchopulmonary dysplasia and CRP, and IGF-1 with invasive mechanical ventilation, CRP and PCT.

CONCLUSIONS

In addition to the known effect on linear growth failure, sustained SIR induces lower bone mass accrual related to higher GH and lower IGF-1 levels in VPI.

IMPACT

Very preterm infants (VPI) with sustained systemic inflammatory response (SIR) compared with VPI without SIR present stunting, lower bone mass, higher GH and lower IGF-1 levels at term corrected age. SIR may help to explain the influence of non-nutritional factors on growth and body composition in VPI. SIR induces postnatal stunting related to lower bone mass accrual via GH/IGF-1 axis inhibition in VPI. VPI with SIR need special attention to minimize inflammatory stress, which could result in improved postnatal growth. Research on inflammatory-endocrine interactions involved in the pathophysiology of postnatal stunting is needed as a basis for new interventional approaches.

Effects of human milk on body composition and growth in very low birthweight infants

OBJECTIVE

To compare body composition and growth in very low birthweight infants according to their source of human milk: maternal expressed breast milk (MEBM) versus donor breast milk (DBM). We hypothesized that infants fed predominately MEBM would exhibit reduced body fat percentage compared to those fed predominately DBM.

METHODS

Premature infants weighing ≤1500 g on an exclusive human milk diet were enrolled in a single-center study between 2017 and 2021. Demographic data and anthropometric measurements were collected. All infants underwent body composition analysis via dual energy x-ray absorptiometry at 36 weeks corrected post menstrual age.

RESULTS

A total of 60 infants were enrolled and 48 were included in the primary analysis. No differences were detected in percent body fat (14 vs. 12%, p = 0.7) or fat-free mass (2050 vs. 2130 g, p = 0.7). Both groups displayed similar growth and anthropometric measurements. Caloric and macronutrient intake between groups was similar.

CONCLUSION

In the cohort of patients studied, no differences were observed in percent body fat based on primary human milk type intake in the first 28 postnatal days. Further investigation is required in a larger population of exclusive human milk fed preterm infants to determine if body composition differences exist based on an infant's primary human milk source.

IMPACT

Premature infants are at risk for altered body composition at term corrected age, specifically increased body fat percentage, which may have implications for the future. To our knowledge this is the first study exploring body composition outcomes based on an infant's primary human milk source. Infants fed exclusive human milk (e.g., donor vs. maternal) displayed similar percent body fat and growth outcomes.

Expression of specific signaling components related to muscle protein turnover and of branched-chain amino acid catabolic enzymes in muscle and adipose tissue of preterm and term calves

Postnatal metabolism depends on maturation of key metabolic pathways around birth. In this regard, endogenous glucose production is impaired in calves born preterm. Concerning protein metabolism, the rates of protein turnover are greater during the neonatal period than at any other period of postnatal life. The mammalian target of rapamycin (mTOR) and the ubiquitin-proteasome system (UPS) are considered as the major regulators of cellular protein turnover. The objectives of this study were to investigate (1) the changes in plasma AA profiles, (2) the mRNA abundance of mTOR signaling and UPS-related genes in skeletal muscle, and (3) the mRNA abundance of branched-chain AA (BCAA) catabolic enzymes in skeletal muscle and adipose tissue in neonatal calves with different degree of maturation during the transition to extrauterine life. Calves (n = 7/treatment) were born either preterm (PT; delivered by cesarean section 9 d before term) or at term (T; spontaneous vaginal delivery) and were left unfed for 1 d. Calves in treatment TC were also spontaneously born but were fed colostrum and transition milk for 4 d. Blood samples were collected from all calves at birth and at 24 h of life. Additional blood samples were taken 2 h after feeding (26 h of life) for PT and T calves, and on d 4 of life for TC, to determine plasma glucose, urea, and AA. Tissue samples from 3 muscles [M. longissimus dorsi (MLD), M. semitendinosus (MST), and M. masseter (MM)], and kidney fat were collected following euthanasia at 26 h after birth (PT, T) or on d 4 of life (TC) at 2 h after feeding. The concentrations of the majority of plasma AA (Ala, Gln, Asn, Cit, Lys, Orn, Thr, and Tyr), nonessential AA, and total AA were greater during the first 24 h and also before and 2 h after feeding in PT than in T. The ratio of plasma BCAA to the aromatic AA (Tyr and Phe) was greatest in TC, followed by T, and least in PT. The mRNA abundance of mTOR and ribosomal protein S6 kinase 1 (S6K1) in MLD and MM was greater in PT and T than in TC. The mRNA abundance of muscle-specific ligases FBXO32 (F-box only protein 32) in the 3 different skeletal muscles and TRIM63 (tripartite motif containing 63) in MLD was greater in PT and T than in TC; in MM, TRIM63 mRNA was greatest in PT. The mRNA for BCKDHA and BCKDHB (the α and β polypeptide of branched-chain α-keto acid dehydrogenase) in kidney fat was elevated in PT and T compared with TC, suggesting a possible enhancement of BCAA oxidation as energy source to cover the energetic and nutritional postnatal demands in PT and T in a starved state. The increased abundances of mTOR-associated signaling factors and muscle-specific ligase mRNA indicate a greater rate of protein turnover in muscles of PT and T in a starved state. Elevated plasma concentrations of several AA may result from enhanced muscle proteolysis and impaired conversion to glucose in the liver of PT calves.

The Thin But Fat Phenotype is Uncommon at Birth in Indian Babies

BACKGROUND

Indian babies are hypothesized to be born thin but fat. This has not been confirmed with precise measurements at birth. If it is true, it could track into later life and confer risk of noncommunicable diseases (NCDs).

OBJECTIVES

Primarily, to accurately measure percentage of body fat (%BF) and body cell mass (BCM) in Indian babies with normal birth weight, compare them across different gestational ages and sex, and test the hypothesis of the thin but fat phenotype in Indian babies. Secondarily, to examine the relation between body weight and body fat in Indian babies.

METHODS

Term newborns (n = 156) weighing ≥2500 g, from middle socioeconomic status mothers were recruited in Bengaluru, India, and their anthropometry, %BF (air displacement plethysmography), and BCM (whole-body potassium counter) were measured. Maternal demography and anthropometry were recorded. The mean %BF and its dispersion were compared with earlier studies. The relation between newborn %BF and body weight was explored by regression analysis.

RESULTS

Mean birth weight was 3.0 ± 0.3 kg, with mean %BF 9.8 ± 3.5%, which was comparable to pooled estimates of %BF from published studies (9.8%; 95% CI: 9.7, 10.0; P > 0.05). Appropriate-for-gestational age (AGA) babies had higher %BF (1.8%) compared to small-for-gestational age (SGA) babies (P < 0.01). Mean %BCM of all babies at birth was 35.4 ± 10.5%; AGA babies had higher %BCM compared to SGA babies (7.0%, P < 0.05). Girls in comparison to boys had significantly higher %BF and lower %BCM. Body weight was positively associated with %BF.

CONCLUSION

Indian babies with normal birth weight did not demonstrate the thin but fat phenotype. Body weight and fat had positive correlation, such that SGA babies did not show a preservation of their %BF. These findings will have relevance in planning optimal interventions during early childhood to prevent NCDs risk in adult life.

Extremely Preterm Infants Have a Higher Fat Mass Percentage in Comparison to Very Preterm Infants at Term-Equivalent Age

Background: Early nutritional support of preterm infants is important because it influences long-term health and development. Body composition has an influence on cardiovascular disease, metabolic syndrome, and neurocognitive outcome in the long term. Objective: To assess body composition in preterm infants <32 weeks of gestation at term-equivalent age and to analyze the influence of an optimized nutritional approach. Methods: This is a prespecified secondary outcome analysis of a prospective observational study comparing the body composition in regard to gestational age. The preterm infants were classified according to gestational age as extremely preterm infants (<28 weeks gestation at birth) and very preterm infants (≥28 weeks gestation at birth) and according to weight percentile as appropriate for gestational age and small for gestational age. Body composition was determined by air displacement plethysmography using the PEA POD. The preterm infants obtained nutrition according to the ESPGHAN 2010 Guidelines. Results: Seventy-four preterm infants were analyzed. The mean (SD) gestational age was 28.7 (2.4) weeks, and birth weight was 1,162 (372) g. Fat mass percentage was significantly higher in extremely preterm infants in comparison to very preterm infants [17.0, 95% confidence interval (CI) 15.9-18.1 vs. 15.5, 95% CI 14.7-16.2]. There was no significant difference of fat mass percentage according to weight percentiles. Conclusions: Extremely preterm infants had a significantly higher fat mass percentage compared to very preterm infants at term-equivalent age. There was no significant difference of fat mass percentage according to weight percentiles.

An Open-label Randomized Controlled Trial to Compare Weight Gain of Very Low Birth Weight Babies with or without Addition of Coconut Oil to Breast Milk

BACKGROUND

Nutritional guidelines involving the feeding of very low birth weight babies (VLBW) recommend addition of Human Milk Fortifiers to breast milk. Owing to financial constraints, it is a practice in low- and middle-income countries (LMIC) to add coconut oil to aid better weight gain. There are inadequate data on improvement of growth parameters with oral coconut oil supplementation of breast milk.

METHODS

In this randomized controlled trial, we measured growth parameters and body composition of 60 babies who received either breast milk with coconut oil or breast milk alone. Randomization was stratified according to intrauterine growth appropriate for gestational age (n = 30) and small for gestational age (n = 30).

RESULTS

There was no difference in weight gain between the two groups. The weight gain velocity was 15 ± 3.6 and 14.4 ± 3.4 g/kg/day (p value = 0.49) in the breast milk alone and in the breast milk with coconut oil group, respectively. There was no difference in increase in head circumference and length. Triceps skinfold thickness (n = 56) was similar in both groups, but subscapular skinfold thickness was significantly more in the coconut oil group. Total body fat percentage did not differ between the groups (25.2 ± 4.3 vs. 25.5 ± 4.3%, p = 0.79).

CONCLUSION

Oral supplementation of coconut oil along with breast milk did not increase growth parameters or result in change in body composition in very low birth weight (VLBW) babies.

Impact of prematurity for pancreatic islet and beta-cell development

As increasing numbers of babies born preterm survive into adulthood, it is becoming clear that, in addition to the well-described risks of neurodevelopmental sequelae, there also are increased risks for non-communicable diseases, including diabetes. Epidemiological studies indicate that risks are increased even for birth at late preterm and early term gestations and for both type 1 and type 2 diabetes. Thus, factors related to preterm birth likely affect development of the fetal and neonatal beta-cell in addition to effects on peripheral insulin sensitivity. These factors could operate prior to preterm birth and be related to the underlying cause of preterm birth, to the event of being born preterm itself, to the postnatal care of the preterm neonate or to a combination of these exposures. Experimental evidence indicates that factors may be operating during all these critical periods to contribute to altered development of beta-cell mass in those born preterm. Greater understanding of how these factors impact upon development of the pancreas may lead to interventions or management approaches that mitigate the increased risk of later diabetes.

Air displacement plethysmography (pea pod) in full-term and pre-term infants: a comprehensive review of accuracy, reproducibility, and practical challenges

Air displacement plethysmography (ADP) has been widely utilised to track body composition because it is considered to be practical, reliable, and valid. Pea Pod is the infant version of ADP that accommodates infants up to the age of 6 months and has been widely utilised to assess the body composition of full-term infants, and more recently pre-term infants. The primary goal of this comprehensive review is to 1) discuss the accuracy/reproducibility of Pea Pod in both full- and pre-term infants, 2) highlight and discuss practical challenges and potential sources of measurement errors in relation to Pea Pod operating principles, and 3) make suggestions for future research direction to overcome the identified limitations.

Smell and taste in the preterm infant

Olfaction and gustation are critical for the enjoyment of food but also have important metabolic roles, initiating the cephalic phase response that sets in train secretion of hormones important for metabolism and digestion before any food is actually ingested. Smell and taste receptors are functional in the fetus and there is evidence for antenatal learning of odours. Despite enteral nutrition and metabolism being major issues in the care of very preterm infants, often little consideration is given to the potential role of smell and taste in supporting these processes, or in the role they may have in encoding hypothalamic circuitry in a way that promotes healthy metabolism in the post‑neonatal period. This review will discuss the evidence for the role of smell and taste in the newborn infant.

Review: Is rapid fat accumulation in early life associated with adverse later health outcomes?

This review discusses ways in which the maternal environment and placental function affect the birth weight and adult health outcomes of offspring. These maternal and placental factors have varying and sometimes opposing effects on birth weight, resulting in infants that are born small for gestational age (SGA), large for gestational age (LGA) or preterm. However, all these alterations in weight have similar effects on adult health, increasing the risk of obesity and its associated cardiovascular and metabolic disorders. While birth weight has been used as a marker for risk of adverse adult health, we propose that a common feature of all these scenarios - early accumulation of excess body fat - may be a better marker than birth weight alone. Furthermore, altered neonatal fat accumulation may be more closely related to the mechanism by which maternal environment and placental adaptation mediate effects on adult health. We suggest that more research should be focussed on early fat accretion, factors that promote fat accretion and if it can be avoided, and whether it would be beneficial to try to reduce fat accumulation in early life.

Impact of placental insufficiency on fetal skeletal muscle growth

Intrauterine growth restriction (IUGR) caused by placental insufficiency is one of the most common and complex problems in perinatology, with no known cure. In pregnancies affected by placental insufficiency, a poorly functioning placenta restricts nutrient supply to the fetus and prevents normal fetal growth. Among other significant deficits in organ development, the IUGR fetus characteristically has less lean body and skeletal muscle mass than their appropriately-grown counterparts. Reduced skeletal muscle growth is not fully compensated after birth, as individuals who were born small for gestational age (SGA) from IUGR have persistent reductions in muscle mass and strength into adulthood. The consequences of restricted muscle growth and accelerated postnatal "catch-up" growth in the form of adiposity may contribute to the increased later life risk for visceral adiposity, peripheral insulin resistance, diabetes, and cardiovascular disease in individuals who were formerly IUGR. This review will discuss how an insufficient placenta results in impaired fetal skeletal muscle growth and how lifelong reductions in muscle mass might contribute to increased metabolic disease risk in this vulnerable population.

Body composition in late preterm infants according to percentile at birth

BACKGROUND

The data on body composition of late preterm infants, evaluated according to percentile at birth, are scarce. The study aimed to investigate body composition of late preterm infants, according to percentile at birth, and to compare their body composition with that of term newborns.

METHODS

A total of 122 (99 appropriate and 23 small for gestational age (SGA)) late preterm infants underwent growth and body composition assessment using an air displacement plethysmography system on the fifth day of life and at term. The reference group was composed of 42 healthy, term, breast-fed infants.

RESULTS

At birth, appropriate and SGA late preterm infants had lower fat mass and fat-free mass indexes than term newborns. The fat mass and fat-free mass content increased significantly throughout the study, irrespective of percentile at birth. At term, fat mass index, but not fat-free mass index, was higher in both appropriate and SGA late preterm infants than in term newborns.

CONCLUSION

Late preterm infants, irrespective of their percentile at birth, show postnatal growth characterized by predominant fat mass accretion. The potential long-term health clinical implications of these findings need to be further elucidated.

Mid-arm circumference is a reliable method to estimate adiposity in preterm and term infants

BACKGROUND

Premature birth is associated with increased adipose deposition after birth. Standard anthropometry (body weight, length, and head circumference) may not adequately assess fat deposition. Validated methods to assess adiposity are needed to optimize growth quality in preterm infants. The purpose of this study was to identify covariates of infant body fat.

METHODS

Air displacement plethysmography (ADP), standard anthropometry, and body circumferences were measured at hospital discharge in preterm (n = 28; 31-35 wk postmenstrual age (PMA)) and term (n = 28; 38-41 wks PMA) infants.

RESULTS

Body weight, length, and head circumference were lower for preterm infants (P < 0.05) at hospital discharge compared with that of term infants. Despite smaller body size and younger PMA, preterm infant percent body fat (%BF) by ADP was 12.33 ± 4.15% vs. 9.64 ± 4.01% in term infants (P = 0.01). Mid-arm circumference (MAC) is a covariate of %BF in both preterm and term infants (adjusted R(2) = 0.49; P < 0.001). In preterm infants alone, MAC accounted for 60.4% of the variability of percent body fat (%BF) by ADP (P < 0.01).

CONCLUSIONS

Preterm infants have increased body fat deposition as they approach term-corrected age, and MAC is a reliable, low-cost measure for monitoring infant body fat deposition in preterm and term infants.

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.

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.

Infant body composition in the PEA POD® era: what have we learned and where do we go from here?

The availability of clinically feasible infant body composition assessment can inform current questions regarding the developmental origins of chronic disease. A strategic approach will facilitate more rapid advancement in knowledge. The objective of this study was to summarize published evidence and ongoing research activity in infant body composition using the PEA POD® infant body composition system. All published studies using the PEA POD® were identified and grouped according to study population and question. All centers with PEA POD® units were invited to participate in an online survey regarding past, current and future PEA POD® use, and results were analyzed using descriptive statistics. The resulting information was used to identify gaps or limitations in existing knowledge, thus highlighting potential research priorities. Twenty-seven published articles were identified and grouped into six research themes. Although the number of infants studied is significant in some areas, interpretation of data is limited by methodological differences. Survey responses were received from 16 of ∼60 centers. Research themes echoed those identified from the published literature. Controlling for or reporting potential confounding variables is essential for understanding infant body composition data. Measurement of health outcome variables would be helpful in identifying associations.

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.

Mechanical-tactile stimulation (MTS) intervention in a neonatal stress model alters adult adipose tissue deposition and prevents hyperinsulinemia in male rats

Preterm infants are exposed to numerous stressors during hospitalization and by term corrected gestational age they have lower body weight but a greater proportion of total body as well as abdominal visceral adipose tissue (VAT) accumulation. Greater abdominal VAT stores have a known association with metabolic syndrome. Mechanical-tactile stimulation (MTS) improves modulation of stress response in both humans and rodents. We hypothesize that MTS, administered during an established model of neonatal stress, would decrease stress-driven adiposity and prevent associated metabolic imbalances in adult rats. Neonatal stress, administered to rat pups from postnatal days 5 to P9, consisted of needle puncture and hypoxic/hyperoxic challenge during 60 min of maternal separation (STRESS; n=20). Mechanical-tactile stimulation (MTS; n=20) was administered to rat pups for 10 min during maternal separation in the stress protocol. Control animals received standard care (CTL; n=20). MRI measured adult (P120) abdominal total fat mass, subcutaneous (SAT) and visceral adipose tissue (VAT). Body weight and fasting serum adiponectin, leptin, glucose, insulin, and corticosterone were also measured. STRESS results in elevated VAT/SAT ratio compared to CTL but lower abdominal total fat mass and abdominal SAT. STRESS males experience hyperinsulinemia. Both STRESS and MTS had elevated leptin with lower adiponectin and corticosterone compared to CTL. In summary, neonatal stress promotes greater abdominal VAT accumulation and, in males, caused hyperinsulinemia and hypoadiponectinemia. Importantly, MTS normalized the VAT/SAT ratio and prevented hyperinsulinemia. We speculate that MTS ameliorates some of the negative metabolic consequences of early life perturbations due to neonatal stress exposure.

Postnatal catch-up fat after late preterm birth

BACKGROUND

Late preterm birth accounts for 70% of preterm births. The aim of the study was to investigate the postnatal weight gain and weight gain composition changes in a cohort of late preterm infants.

METHODS

A total of 49 late preterm infants (mean birth weight 2,496 ± 330 g and gestational age 35.2 ± 0.7 wks) underwent growth and body composition assessment by an air displacement plethysmography system on the fifth day of life, at term, and at 1 and 3 mo of corrected age. The reference group was composed of 40 healthy, full-term, breast-fed infants.

RESULTS

The late preterm infants showed a Δ fat mass gain between birth and term-corrected age equal to 182%. As compared with full-term infants, at term and 1 mo of corrected age mean weight (3,396 ± 390 vs. 3,074 ± 409 g and 4,521 ± 398 vs. 4,235 ± 673 g, respectively) and percentage of fat mass (16.1 ± 4.6 vs. 8.9 ± 2.9 and 22.6 ± 4.2 vs. 17.4 ± 4.0, respectively) were significantly higher in late preterm infants, whereas no difference among groups was found at 3 mo.

CONCLUSION

Rapid postnatal catch-up fat was found in these infants. Further studies are needed to investigate whether this short-term increase in fat mass may modulate the risk of chronic diseases or represent an adaptive mechanism to extrauterine life.

Adiposity in children and adolescents: correlates and clinical consequences of fat stored in specific body depots

The 2011 Pennington Biomedical Research Center's Scientific Symposium focused on adiposity in children and adolescents. The symposium was attended by 15 speakers and other invited experts. The specific objectives of the symposium were to (i) integrate the latest published and unpublished findings on the laboratory and clinical assessment of depot-specific adiposity in children and adolescents, (ii) understand the variation in depot-specific adiposity and related health outcomes associated with age, sex, maturation, ethnicity and other factors and (iii) identify opportunities for incorporating new markers of abdominal obesity into clinical practice guidelines for obesity in children and adolescents. This symposium provided an overview of important new advances in the field and identified directions for future research. The long-term goal of the symposium is to aid in the early identification of children and adolescents who are at increased health risk because of obesity and obesity-related conditions.

Evaluation of air-displacement plethysmography for body composition assessment in preterm infants

BACKGROUND

Adiposity may contribute to the future risk of disease. The aim of this study was to evaluate the accuracy and reliability of an air-displacement plethysmography (ADP) system to estimate percentage fat mass (%FM) in preterm infants and to evaluate interdevice reliability in infants.

METHODS

A total of 70 preterm and 9 full-term infants were assessed. The accuracy of ADP measurements was assessed by determining reference %FM values using H(2)(18)O dilution measurement.

RESULTS

Mean %FM by ADP was 5.67 ± 1.84 and mean %FM by H(2)18O dilution was 5.99 ± 2.56. Regression analysis showed that %FM by ADP was associated with %FM by H(2)(18)O dilution (R2 = 0.63, SE of estimate (SEE) = 1.65, P = 0.006). Bland-Altman analysis showed no bias (r = -0.48, P = 0.16) and 95% limits of agreement were -3.40 to 2.76 %FM. There was no difference in mean interdevice reliability %FM values (8.97 vs. 8.55 %FM) between ADP 1 and 2. Regression analysis indicated a low SEE (1.14% FM) and high R2 (0.91); 95% limits of agreement were -1.87 to 2.71 %FM. The regression line did not differ significantly from the line of identity.

CONCLUSION

ADP is a noninvasive, reliable, and accurate technique to measure preterm infants' body composition in both research and clinical settings.

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.

Customized versus population-based growth curves: prediction of low body fat percent at term corrected gestational age following preterm birth

OBJECTIVE

Compare customized versus population-based growth curves for identification of small-for-gestational-age (SGA) and body fat percent (BF%) among preterm infants.

METHODS

Prospective cohort study of 204 preterm infants classified as SGA or appropriate-for-gestational-age (AGA) by population-based and customized growth curves. BF% was determined by air-displacement plethysmography. Differences between groups were compared using bivariable and multivariable linear and logistic regression analyses.

RESULTS

Customized curves reclassified 30% of the preterm infants as SGA. SGA infants identified by customized method only had significantly lower BF% (13.8 ± 6.0) than the AGA (16.2 ± 6.3, p = 0.02) infants and similar to the SGA infants classified by both methods (14.6 ± 6.7, p = 0.51). Customized growth curves were a significant predictor of BF% (p = 0.02), whereas population-based growth curves were not a significant independent predictor of BF% (p = 0.50) at term corrected gestational age.

CONCLUSION

Customized growth potential improves the differentiation of SGA infants and low BF% compared with a standard population-based growth curve among a cohort of preterm infants.

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.

Fat and fat-free mass at birth: air displacement plethysmography measurements on 350 Ethiopian newborns

LBW increases the risk of a number of noncommunicable diseases in adulthood. However, birth weight (BW) cannot describe variability in infant body composition (BC). Variability in fat mass (FM) and fat-free mass (FFM) at birth may be particularly important in low-income countries because they undergo nutritional transition. There is a need for data on birth BC and its predictors from low-income countries in transition. We assessed absolute FM and FFM at birth and examined the role of gender, parity, GA, and LBW as predictors of birth BC. FM and FFM were assessed within 48 h of birth on 350 Ethiopian newborns using air displacement plethysmography (ADP). Female gender and being an infant of primi- or secundiparous mothers predicted lower BW and lower birth FFM but not FM, compared with male gender and infants of multiparous mothers, respectively. There was a positive linear relationship between BW and relative amount of FM for boys and girls. This study presents reference data on birth FM and FFM from a low-income setting and provides background for further longitudinal mapping of the relationship between fetal BC, childhood growth, and adult disease.

Small for gestational age preterm infants: nutritional strategies and quality of growth after discharge

Infants born preterm are at high risk for poor growth achievement. Small for gestational age (SGA (birth weight below the 10th percentile) preterm infants are even more prone to develop postnatal growth retardation in the early neonatal period, as they do not have a large storage of protein/energy. Both SGA and appropriate for gestational age (AGA: birth weight between the 10th and 90th percentiles) infants show persistent postnatal growth failure after discharge. Although the available data clearly demonstrate that preterm infants, especially if born SGA, exhibit postnatal growth retardation at the time of hospital discharge, the importance of the nutritional post discharge management has not been sufficiently taken into account. We have recently conducted a randomized controlled trial to assess whether infants born SGA may benefit from an enriched post discharge formula. This study suggests that the growth pattern in SGA preterm infants is not affected by the consumption of an enriched post discharge formula. The ponderal and linear growth of these infants does not accelerate to achieve early catch up growth. However, as far as the quality of growth is concerned, the fat mass accretion after term decelerates, so that an increase of fat free mass accretion takes place. Future research effort should be directed toward longer follow up and personalized nutrition management.

Ultrasound assessment of intrauterine growth restriction: relationship to neonatal body composition

OBJECTIVE

The objective of the study was to compare prenatal ultrasound parameters for intrauterine growth restriction (IUGR) with newborn percent body fat (%BF).

STUDY DESIGN

This was a prospective study of 87 pregnancies followed with ultrasound. Subjects were categorized into 3 groups: estimated fetal weight (EFW) less than the 10th percentile, abdominal circumference (AC) less than the fifth percentile, and normal biometry. Neonatal %BF by air displacement plethysmography was compared between each group using multivariable analyses.

RESULTS

The %BF in the EFW less than the 10th percentile group (5.1 ± 2.9%) was significantly lower than either AC less than the fifth percentile (9.5 ± 3.3%) or normal groups (11.6 ± 5.6%). EFW less than the 10th percentile best predicted %BF by regression model. Neonatal morbidity was not significantly higher in the EFW less than the 10th percentile group.

CONCLUSION

Newborn %BF was significantly lower in infants with EFW less than the 10th percentile compared with AC less than the fifth percentile, an intermediate finding. An AC less than the fifth percentile on ultrasound does not reflect the same severity of IUGR as EFW less than the 10th percentile.

Body composition changes in preterm infants following hospital discharge: comparison with term infants

BACKGROUND AND OBJECTIVES

Infants experiencing catch-up growth devote a greater proportion of their energy to fat deposition, potentially at the expense of gains in lean body mass. The objective of the present study was to compare the body composition of preterm and term infants after hospital discharge and to determine the effect of gestational age (GA), birth size, nutrition, and illness on growth in fat-free mass (FFM) after hospitalization.

PATIENTS AND METHODS

Anthropometric measurements and body composition testing via air displacement plethysmography were performed on 26 appropriate-for-gestational-age (AGA) preterm (mean GA 31.5  ±  2.7 weeks) and 97 AGA term (mean GA 39.8 ± 1.0 weeks) infants at term corrected age (CA) and at 3 to 4 months CA.

RESULTS

At term CA, preterm infants had lower FFM (3.0 vs 3.3 kg, P = 0.001), higher percentage of body fat (18.7% vs 15.2%, P < 0.0001), lower weight (P =0.04), and shorter length (P = 0.001) than term infants. By 3 to 4 months CA, weight, length, percentage of body fat, and FFM were similar in the 2 groups. GA, inpatient nutrition, and illness were associated with FFM at 4 months CA in the preterm infants (P < 0.05).

CONCLUSIONS

Markedly lower FFM and higher adiposity were observed in preterm infants at term CA, but these differences had lessened and were no longer statistically significant at 3 to 4 months CA. Although early nutrition was associated with growth trajectories in the hospital, the continuing influence of early illness on postdischarge growth suggests that nonnutritional factors (eg, disturbances in the growth hormone axis) also may affect body composition trajectories of preterm infants.

Fat-free mass hydration in newborns: assessment and implications for body composition studies

AIM

Equipment (Pea Pod) offering new possibilities to assess infant body composition has recently become available and has already been used in several studies. In the Pea Pod, body density is converted to body composition using one of two models ('Fomon' or 'Butte') with different water content in fat-free mass (hydration factor, HF). In healthy full-term infants, we assessed HF and its biological variability in 12 newborns and calculated body composition using the two models at 1 and 12 weeks in 108 infants. Body weight and volume were assessed in Pea Pod, and body water was assessed using isotope dilution.

RESULTS

Hydration factor was 80.9% with low biological variability (0.8% of average HF). Body fat (%) was significantly lower at 1 and 12 weeks when calculated using the 'Butte' model than when using the 'Fomon' model. The difference was more pronounced at one than at 12 weeks.

CONCLUSION

  Our HF value agrees with that in the 'Fomon' model, its low biological variability can be reconciled with the statement that Pea Pod is accurate in newborns and 'Fomon' is the best available model for studies in Pea Pod.

Early postnatal nutrition and programming of the preterm neonate

Early postnatal nutrition is a vital determinant of adult health; this is particularly true for the infant born prematurely and cared for in a hospital setting such as the neonatal intensive care unit. Human and animal studies support the contribution of postnatal dietary composition and the rate of extrauterine growth to long-term metabolic outcomes. One mechanism by which postnatal nutrition affects long-term outcome is via developmental programming. Programming, or the modulation of gene expression to impart a short-term advantage accompanied by a long-term cost, may be achieved by epigenetic modifications to chromatin. This review summarizes the details of postnatal nutritional content and rate of growth on the development of metabolic disease. The role of epigenetics in developmental programming of the preterm infant is also discussed, with an emphasis on animal models of dietary manipulation and directions in which the field must move in order to formulate effective feeding strategies for the preterm infant.

Reliability of routine clinical measurements of neonatal circumferences and research measurements of neonatal skinfold thicknesses: findings from the Born in Bradford study

Assessing neonatal size reliably is important for research and clinical practice. The aim of this study was to examine the reliability of routine clinical measurements of neonatal circumferences and of skinfold thicknesses assessed for research purposes. All measurements were undertaken on the same population of neonates born in a large maternity unit in Bradford, UK. Technical error of measurement (TEM), relative TEM and the coefficient of reliability are reported. Intra-observer TEMs for routine circumference measurements were all below 0.4 cm and were generally within ± 2-times the mean. Inter-observer TEM ranged from 0.20 to 0.36 cm for head circumference, 0.19 to 0.39 cm for mid upper arm circumference and from 0.39 to 0.77 cm for abdominal circumference. Intra and inter-observer TEM for triceps skinfold thickness ranged from 0.22 to 0.35 mm and 0.15 to 0.54 mm, respectively. Subscapular skinfold thickness TEM values were 0.14 to 0.25 mm for intra-observer measurements and 0.17 to 0.63 mm for inter-observer measurements. Relative TEM values for routine circumferences were all below 4.00% but varied between 2.88% and 14.23% for research skinfold measurements. Reliability was mostly between 80% and 99% for routine circumference measurements and ≥ 70% for most research skinfold measurements. Routine clinical measurements of neonatal circumferences are reliably assessed in Bradford. Assessing skinfolds in neonates has variable reliability, but on the whole is good. The greater intra-observer, compared with inter-observer, reliability for both sets of measurements highlights the importance of having a minimal number of assessors whenever possible.

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.

Body composition in full-term healthy infants measured with air displacement plethysmography at 1 and 12 weeks of age

AIM

To use Pea Pod, a device based on air displacement plethysmography, to study body composition of healthy, full-term infants born to well-nourished women with a western life-style.

METHODS

Body composition was assessed in 53 girls and 55 boys at 1 week (before 10 days of age) and at 12 weeks (between 77 and 91 days of age).

RESULTS

At 1 week girls contained 13.4 +/- 3.7% body fat and boys 12.5 +/- 4.0%. At 12 weeks, these figures were 26.3 +/- 4.2% (girls) and 26.4 +/- 5.1% (boys). Body fat (%) did not differ significantly between the genders. Body fat (%) at the two measurements was not correlated. At 1 week, the weight (r = 0.20, p = 0.044) and BMI (r = 0.26, p = 0.007) of the infants, but not their body fat (g, %) or fat free mass (g), correlated with BMI before pregnancy in their mothers.

CONCLUSIONS

Pea Pod has potential for use in studies investigating the effect of external (i.e. nutritional status) and internal (i.e. age, gender, gestational age at birth) factors on infant body composition. This may be of value when studying relationships between the nutritional situation during early life and adult health.