Determinants of body composition in preterm infants at the time of hospital discharge

Utilizing preterm infant body composition assessments to guide neonatal nutrition

PURPOSE OF REVIEW

The use of body composition to assess the quality of infant growth may add valuable information to pediatric clinical care. Preterm infants have differences in their fat and muscle mass development compared with infants born at term, which may be related to their early nutritional exposures. This review focuses on recent studies examining early nutrition in preterm infants and related body composition outcomes in the newborn period and beyond.

RECENT FINDINGS

Overall, the evidence shows that early nutrient delivery in parenteral nutrition and through formula supplementation or human milk fortification is associated with increased fat-free mass or lean mass in early life. However, future research is needed to fully understand the link between these body composition changes and longitudinal outcomes in preterm infants.

SUMMARY

Inclusion of body composition assessments in preterm infant nutrition research is critical to understand the factors associated with differences in adiposity and lean mass development in preterm infants. Medical fragility in preterm infants limits the routine use of body composition assessment tools which are currently validated, and additional studies are needed to thoroughly assess other methods which may be more feasible to integrate into bedside routine.

Body Composition in Preterm Infants: Current Insights and Emerging Perspectives

In recent years, significant advancements in respiratory and nutritional care have markedly improved the survival rates of preterm infants and enhanced long-term health outcomes. Despite these improvements, emerging research highlights the lasting impacts of early growth patterns on an individual's health trajectory. Adults born prematurely face a higher incidence of health issues related to their early birth. The American Academy of Pediatrics recommends that preterm infants should achieve growth rates similar to those of fetuses, with clinicians emphasizing nutrition delivery to help these infants reach their expected weight for gestational age. However, this approach often results in altered body composition, characterized by increased fat mass and decreased fat-free mass compared to full-term infants. Air displacement plethysmography stands out as a highly reliable method for measuring preterm body composition, while DEXA scans, despite their reliability, tend to overestimate body fat. Other methods include bioelectric impedance, isotope dilution, MRI, ultrasound, and skinfold thickness, each with its own strengths and limitations. In this paper, we aim to raise awareness among neonatal clinicians about the importance of achieving acceptable neonatal body composition. We discuss the pros and cons of different body composition measurement methods, the impact of nutrition and other factors on body composition in preterm infants, long-term follow-up data, and the potential use of body composition data to tailor nutritional interventions in NICU and post-discharge settings. This comprehensive approach is designed to optimize health outcomes for preterm newborns by focusing on their body composition from an early stage.

Impact of Nutrient Intake on Body Composition in Very Low-Birth Weight Infants Following Early Progressive Enteral Feeding

Preterm infants have increased body adiposity at term-equivalent age and risk of adverse metabolic outcomes. The aim of the study was to define how nutrient intake may impact body composition (BC) of very low-birth weight infants fed with early progressive enteral feeding and standard fortification. Eighty-six infants with <1500 g birth weight were included in the BC study and stratified into extremely preterm (EP) and very preterm (VP) groups. Nutrient intake was calculated during the first 28 days and BC assessed by dual X-ray absorptiometry at discharge and by skinfold thickness at 12 months of corrected age (CA). Total nutrient intake did not differ between the groups. EP infants had a higher fat mass percentage at discharge than VP infants (24.8% vs. 19.4%, p < 0.001); lean mass did not differ. None of the nutrients had any impact on BC of EP infants. Protein intake did not result in a higher lean mass in either group; fat intake was a significant predictor of increased fat mass percentage in VP infants at discharge (p = 0.007) and body adiposity at 12 months of CA (p = 0.021). Nutritional needs may depend on gestational age and routine fortification should be used with caution in more mature infants.

Predicting body fat percentage at 36 weeks of postmenstrual age in infants born preterm: A diagnostic accuracy study

BACKGROUND

Current standards for assessing body composition can be costly and technically challenging. There is a need for a predictive equation that combines multiple clinical and anthropometric factors to predictbody composition outcomes at 36 weeks of postmenstrual age (PMA) or discharge.

METHODS

To develop a widely applicable equation that predicts body fat percentage in preterm infants, we analyzed anthropometric data collected prospectively from a cohort of infants born very preterm between 2017 and 2018. We integrated clinical variables significantly associated with adiposity into a predictive equation using Bayesian linear regression models and leave-one-out cross-validation.

RESULTS

We analyzed data from 86 infants born at 32 weeks of gestation or less (median gestational age, 30 weeks; mean birthweight, 1471 ± 270 g). Weight gain and increase in length per week from birth to 36 weeks of PMA, midarm circumference at 36 weeks of PMA, male sex, and higher enteral fluid intake (>180 ml/kg/day) were the strongest predictors of body fat percentage in the model with the highest predictive value (R2  = 0.65). The correlation between actual and predicted body fat percentage using this Bayesian model was high (r = 0.82).

CONCLUSIONS

Weight gain and increase in length per week from birth to 36 weeks of PMA, midarm circumference at 36 weeks of PMA, male sex, and enteral fluid intake are significant predictors of body fat percentage at 36 weeks of PMA in very preterm infants.

Infant body composition: A comprehensive overview of assessment techniques, nutrition factors, and health outcomes

Body composition assessment is a valuable tool for clinical assessment and research that has implications for long-term health. Unlike traditional measurements such as anthropometrics or body mass index, body composition assessments provide more accurate measures of body fatness and lean mass. Moreover, depending on the technique, they can offer insight into regional body composition, bone mineral density, and brown adipose tissue. Various methods of body composition assessment exist, including air displacement plethysmography, dual-energy x-ray absorptiometry, bioelectrical impedance, magnetic resonance imaging, D3 creatine, ultrasound, and skinfold thickness, each with its own strengths and limitations. In infants, several feeding practices and nutrition factors are associated with body composition outcomes, such as breast milk vs formula feeding, protein intake, breast milk composition, and postdischarge formulas for preterm infants. Longitudinal studies suggest that body composition in infancy predicts later body composition, obesity, and other cardiometabolic outcomes in childhood, making it a useful early marker of cardiometabolic health in both term and preterm infants. Emerging evidence also suggests that body composition during infancy predicts neurodevelopmental outcomes, particularly in preterm infants at high risk of neurodevelopmental impairment. The purpose of this narrative review is to provide clinicians and researchers with a comprehensive overview of body composition assessment techniques, summarize the links between specific nutrition practices and body composition in infancy, and describe the neurodevelopmental and cardiometabolic outcomes associated with body composition patterns in term and preterm infants.

Body composition in preterm infants: a systematic review on measurement methods

BACKGROUND

There are several methods to measure body composition in preterm infants. Yet, there is no agreement on which method should be preferred.

METHODS

PubMed, Embase.com, Wiley/Cochrane Library, and Google Scholar were searched for studies that reported on the predictive value or validity of body composition measurements in preterms, up to 6 months corrected age.

RESULTS

Nineteen out of 1884 identified studies were included. Predictive equations based on weight and length indices, body area circumferences, skinfold thickness, bioelectrical impedance, and ultrasound did not show agreement with body composition measured with air displacement plethysmography (ADP), dual-energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), or isotope dilution. ADP agreed well with fat mass density measured by isotope dilution (bias -0.002 g/ml, limits of agreement ±0.012 g/ml, n = 14). Fat mass percentage measured with ADP did not agree well with fat mass percentage measured by isotope dilution (limits of agreement up to ±5.8%) and the bias between measurements was up to 2.2%. DXA, MRI, and isotope dilution were not compared to another reference method in preterms.

CONCLUSIONS

DXA, ADP, and isotope dilution methods are considered trustworthy validated techniques. Nevertheless, this review showed that these methods may not yield comparable results.

IMPACT

Based on validation studies that were conducted in a limited number of study subjects, weight and length indices, body area circumferences, skinfold thickness, bioelectrical impedance, and ultrasound seem to be a poor representation of body composition in preterm infants. DXA, ADP, and isotope dilution methods are considered trustworthy and validated techniques. Nevertheless, these methods may not yield comparable results.

Growth trajectory during the first 1000 days and later overweight in very preterm infants

OBJECTIVE

To identify the characteristics of early life growth associated with later overweight or obesity (OWO) in very preterm population.

DESIGN

Length, weight and body mass index (BMI) were prospectively recorded from three prospective, population-based cohorts with 5 years (Loire Infant Follow-up Team (LIFT), EPIPAGE2 (Etude EPIdémiologique sur les Petits Ages GEstationnels 2)) and 15 years (EPIPAGEADO, Etude EPIdémiologique sur les Petits Ages GEstationnels-Adolescents) of follow-up. Missing data were imputed.

SETTING

Regional (LIFT), national (EPIPAGE2) and multiregional (EPIPAGEADO) cohorts in France.

PATIENTS

Eligible infants born before 33 weeks of gestation in 1997 (EPIPAGEADO), between 2003 and 2014 (LIFT), and in 2011 (EPIPAGE2).

MAIN OUTCOME MEASURES

OWO was determined as BMI Z-score >85th percentile of the WHO reference curves at 5 years (LIFT, EPIPAGE2) and 15 years (EPIPAGEADO).

RESULTS

In EPIPAGEADO, LIFT and EPIPAGE2, BMI Z-scores were known for 302 adolescents, 1016 children and 2022 children, respectively. In EPIPAGEADO, OWO was observed in 42 (13.9%, 95% CI 10.5 to 18.3) adolescents. In multivariable models, birthweight Z-score, increase in weight Z-score during neonatal hospital stay and increase in BMI between discharge and at 2 years of corrected age were positively associated with OWO at 15 years (adjusted OR (aOR)=3.65, 95% CI 1.36 to 9.76; aOR=3.82, 95% CI 1.42 to 10.3; and aOR=2.55, 95% CI 1.72 to 3.78, respectively, by Z-score), but change in length Z-score during neonatal hospital stay was negatively associated (aOR=0.41, 95% CI 0.21 to 0.78, p=0.007). These four associations with OWO assessed at 5 years were confirmed in the LIFT and EPIPAGE2 cohorts.

CONCLUSIONS

Change in length Z-score during hospitalisation, a putative proxy of quality of neonatal growth, was negatively associated with risk of later OWO when change in BMI between discharge and at 2 years was included in the multivariable model.

Postnatal growth and body composition in extremely low birth weight infants fed with individually adjusted fortified human milk: a cohort study

This cohort study aimed to evaluate the impact of an individualised nutritional care approach combining standardised fortification with adjustable fortification on postnatal growth and body composition in extremely low birth weight (ELBW) infants. We included ELBW infants admitted to a neonatal intensive care unit and still hospitalised at 35 weeks postmenstrual age (PMA). The fortification of human milk was standardised (multicomponent fortifier) between 70 mL/kg/day and full enteral feeding, and then individualised using adjustable fortification. When weight gain was below 20 g/kg/day, protein or energy was added when serum urea was below or above 3.5 mmol/L, respectively. Postnatal growth failure (PNGF) was defined as being small for gestational age at discharge and/or when the Z-score loss between birth and discharge was higher than 1. Body composition was assessed between 35 and 41 weeks of PMA. Among the 310 ELBW infants included, the gestational age of birth was 26.7 ± 1.8 weeks, and the birth weight was 800 ± 128 g. The mean Z-score difference between birth and discharge was moderately negative for the weight (-0.32), more strongly negative for length (-1.21), and almost nil for head circumference (+ 0.03). Only 27% of infants presented PNGF. At discharge, fat mass was 19.8 ± 3.6%. Multivariable analysis showed that the proportion of preterm formula received and gestational age at birth were independently associated with the percentage of fat mass.  Conclusion: The individualised nutritional care approach applied herein prevented postnatal weight loss in most infants, limited length growth deficit, and supported excellent head circumference growth. What is Known: • At least half of extremely low birth weight infants are small for gestational age at discharge and postnatal growth deficit has been associated with impaired neurocognitive and renal development. • Human milk is the main milk used in neonatology and, although fortification of human milk is a standard of care, there is no consensus regarding the optimal fortification strategy to be adopted. What is New: • Using an approach combining standardised fortification followed by individualised adjustable fortification limited postnatal growth deficit for body weight and head circumference. Postnatal growth failure is not a fatality in extremely low birth weight infants. • Each additional gestational age week at birth resulted in a decrease in fat mass percentage at discharge, which was higher than in foetuses of the same gestational age, likely representing a necessary adaptation to extra-uterine life.

Predictive ability of postnatal growth failure for adverse feeding-related outcomes in preterm infants: an exploratory study comparing Fenton with INTERGROWTH-21st preterm growth charts

BACKGROUND

Postnatal growth failure (PGF) can impact the short- and long-term health outcomes in preterm infants. However, PGF rates vary according to the way it is defined and the growth chart used to monitor the postnatal growth. Fenton-2013 growth charts which suggest following intrauterine fetal growth compared to INTERGROWTH-21st, one specifically constructed for monitoring preterm extrauterine growth.

OBJECTIVE

Exploratory study to determine the PGF definition at first per oral (PO) that is most predictive of adverse oral feeding-related outcomes in preterm infants.

METHODS

Prospectively collected data of preterm infants 24-32 weeks gestation, who were started on cue-based oral feeds at ≤34 weeks gestation were reviewed. Anthropometric data at first PO (weight, length, and head circumference) were compared according to Fenton and INTERGROWTH-21st growth charts. PGF was defined either as <10th percentile, Z-score change (ZSC) of ≥-1.5 from birth, or ZSC of ≥-2.0. Top-quartile (Q4) of feeding-related outcomes (days from first PO to full PO, post-menstrual age at full PO, days from first PO to discharge, and length of hospital stay) was considered as adverse outcome.

RESULTS

Of the 125 infants included, the median birth gestation and weight were 29.4 weeks and 1235 g, respectively. Incidence of appropriate, small, and large for gestational age was similar at birth by both growth charts. ZSC -1.5 for weight by Fenton was significantly higher at first PO vs. INTERGROWTH-21st (p=.02), while percentile <10th and ZSC -2.0 rates were similar. The PGF definition based on individual anthropometrics at first PO that has the best area under the curve (AUC) for adverse feeding-related outcomes was used to create a combined PGF definition for each growth chart. The AUC for the combined PGF for the Fenton and INTERGROWTH-21st was similar (p>.05) and both have moderate sensitivity and negative predictive value, but have low specificity, positive predictive value, and positive likelihood ratio for adverse feeding-related outcomes.

CONCLUSIONS

The tested definitions of PGF at first PO have only small to moderate predictive ability for adverse feeding-related outcomes in preterm infants.

Body composition of extremely preterm infants fed protein-enriched, fortified milk: a randomized trial

BACKGROUND

Critically ill extremely preterm infants fed human milk are often underrepresented in neonatal nutrition trials aimed to determine the effects of enteral protein supplementation on body composition outcomes.

METHODS

Masked randomized trial in which 56 extremely preterm infants 25-28 weeks of gestation were randomized to receive either fortified milk enriched with a fixed amount of extensively hydrolyzed protein (high protein group) or fortified milk without additional protein (standard protein group).

RESULTS

Baseline characteristics were similar between groups. In a longitudinal analysis, the mean percent body fat (%BF) at 30-32 weeks of postmenstrual age (PMA), 36 weeks PMA, and 3 months of corrected age (CA) did not differ between groups (17 ± 3 vs. 15 ± 4; p = 0.09). The high protein group had higher weight (-0.1 ± 1.2 vs. -0.8 ± 1.3; p = 0.03) and length (-0.8 ± 1.3 vs. -1.5 ± 1.3; p = 0.02) z scores from birth to 3 months CA. The high protein group also had higher fat-free mass (FFM) z scores at 36 weeks PMA (-0.9 ± 1.1 vs. -1.5 ± 1.1; p = 0.04).

CONCLUSIONS

Increased enteral intake of protein increased FFM accretion, weight, and length in extremely preterm infants receiving protein-enriched, fortified human milk.

IMPACT

Extremely preterm infants are at high risk of developing postnatal growth failure, particularly when they have low fat-free mass gains. Protein supplementation increases fat-free mass accretion in infants, but several neonatal nutrition trials aimed to determine the effects of enteral protein supplementation on body composition outcomes have systematically excluded critically ill extremely preterm infants fed human milk exclusively. In extremely preterm infants fed fortified human milk, higher enteral protein intake increases fat-free mass accretion and promotes growth without causing excessive body fat accretion.

Body Composition of Preterm Infants following Rapid Transition to Enteral Feeding

OBJECTIVE

This study aimed to evaluate body composition at the time of hospital discharge in very preterm infants following rapid transition to full enteral feeding.

STUDY DESIGN

We conducted a prospective, observational, cross-sectional study and included 105 preterm infants <32 gestational age or birth weight <1,500 g, born between April 2015 and December 2020, following rapid transition to full enteral feeding (≥140 mL/kg/day). Fat mass/total body mass (BF%) and fat-free mass (FFM) were measured at the time of hospital discharge using air displacement plethysmography.

RESULTS

Median and interquartile range (Q1-Q3) of gestational age at birth (GA) was 27.3 (26.1-28.7) weeks and birth weight 845 (687-990) g. Time to reach full enteral feeding was 5 (5-7) days. At 37.6 weeks (36.1-39.0) postmenstrual age (PMA), BF% was 17.0% (14.9-19.8) and FFM 2,161 g (1,966-2,432). BF% was not associated with GA, and not different between small and appropriate for gestational age infants. FFM was significantly lower in infants born small for gestational age.

CONCLUSIONS

Following rapid transition to full enteral feeding, FFM and BF% at discharge were similar to other preterm populations. BF% and FFM were not associated with GA at birth but with PMA at measurement. FFM was lower and BF% higher compared to term infants at birth, suggesting diminished parenchymal growth in preterm infants. Continued monitoring of body composition, metabolic health, and neurological development is needed to study long-term effects.

Effect of parenteral nutrition duration on patterns of growth and body composition in very low-birth-weight premature infants

BACKGROUND

Parenteral nutrition (PN) is essential to support premature infants' growth and varies with enteral nutrition (EN) advancement rates. Data on PN duration's impact on premature infants' growth are limited. The aim of this multicenter observational study was to determine the effect of early PN duration on body composition at term corrected gestational age (CGA) in very low-birth-weight (VLBW) premature infants.

METHODS

VLBW infants exposed to PN in the first week of life and exposed to significantly different EN regimens were divided into two groups on the basis of early PN duration. Infants with a birth weight (BW) <1000 g and PN duration <28 days and infants with a BW 1000-1500 g and PN duration <14 days were assigned to the "short-PN" group. Infants receiving PN for longer durations were assigned to the "long-PN" group. Body composition was assessed via air displacement plethysmography at term CGA or before discharge.

RESULTS

Sixty-two and 53 infants were assigned to the short-PN and long-PN groups, respectively. The two groups were significantly different in BW and GA, so a nested case-control study was conducted after matching 36 infant pairs. Infants in the long-PN group had significantly lower fat-free mass (FFM) z-scores, but both groups had comparable fat mass (FM) z-scores. Long PN was a significant negative predictor of FFM z-score in the multivariate regression analysis.

CONCLUSION

In VLBW premature infants, PN duration is negatively associated with FFM z-scores at term CGA without affecting FM z-scores.

Optimizing Early Neonatal Nutrition and Dietary Pattern in Premature Infants

Providing adequate amounts of all essential macro- and micronutrients to preterm infants during the period of extraordinarily rapid growth from 24 to 34 weeks' postmenstrual age to achieve growth as in utero is challenging yet important, since early growth restriction and suboptimal neonatal nutrition have been identified as risk factors for adverse long-term development. Along with now well-established early parenteral nutrition, this review emphasizes enteral nutrition, which should be started early and rapidly increased. To minimize the side effects of parenteral nutrition and improve outcomes, early full enteral nutrition based on expressed mothers' own milk is an important goal. Although neonatal nutrition has improved in recent decades, existing knowledge about, for example, the optimal composition and duration of parenteral nutrition, practical aspects of the transition to full enteral nutrition or the need for breast milk fortification is limited and intensively discussed. Therefore, further prospective studies on various aspects of preterm infant feeding are needed, especially with regard to the effects on long-term outcomes. This narrative review will summarize currently available and still missing evidence regarding optimal preterm infant nutrition, with emphasis on enteral nutrition and early postnatal growth, and deduce a practical approach.

Different feeding regimens were not associated with variation in body composition in preterm infants

AIM

The aim was to determine body composition and growth in preterm infants based on two different feeding regimens and to assess how standard and individual fortification (IF) affect energy and protein intake. Body composition was assessed at full term and at four months corrected age.

METHODS

Sixty preterm infants born before gestational week 32 were randomized either to IF of mother's breast milk after it had been analyzed or to standard fortification (SF) of mother's breast milk based on the average protein and energy content of breast milk. Body composition was measured at full term and at four months corrected age, using air displacement plethysmography. Growth rate and nutritional intake analyses were also conducted.

RESULTS

At 40 weeks gestational age, there was no difference between weight (g) (IF 3056 ± 472 vs. SF 3119 ± 564), body fat (%) (IF 19 ± 3.3 vs. SF 21 ± 5.6), fat mass, or fat-free mass between the two groups. Furthermore, there was no difference between the groups in weight, length, head circumference, or body composition at four months corrected age.

CONCLUSIONS

Fortification based on breast milk analysis may not improve growth in preterm infants compared to SF. However, both groups were smaller and had a different body composition at term corrected age compared to infants born at term.

Early weight gain trajectories and body composition in infancy in infants born very preterm

BACKGROUND

Concerns are raised about the influence of rapid growth on excessive fat mass (FM) gain in early life and later cardiometabolic health of infants born preterm.

OBJECTIVES

To study the association between postnatal weight gain trajectories and body composition in infancy in infants born very preterm.

METHODS

In infants born <30 weeks gestation, we evaluated associations between weight Z-score trajectories for three consecutive timeframes (NICU stay, level-II hospital stay and at home) and body composition, measured at 2 and 6 months corrected age by air-displacement plethysmography.

RESULTS

Of 120 infants included, median gestational age at birth was 27⁺⁵ (interquartile range 26⁺¹ ;28⁺⁵ ) and birth weight 1015 g (801;1250). The majority of infants did not make up for their initial loss of weight Z-score, but growth and later body composition were within term reference values. Weight gain during NICU stay was not associated with fat mass (absolute, %FM or FM index) in infancy. Weight gain during NICU and level II hospital stay was weakly associated with higher absolute lean mass (LM), but not after adjustment for length (LM index). Weight gain in the level-II hospital was positively associated with fat mass parameters at 2 months but not at 6 months. Strongest associations were found between weight gain at home and body composition (at both time points), especially fat mass.

CONCLUSIONS

Weight gain in different timeframes after preterm birth is associated with distinct parameters of body composition in infancy, with weight gain at home being most strongly related to fat mass.

Breast milk protein content at week 3 after birth and neurodevelopmental outcome in preterm infants fed fortified breast milk

BACKGROUND

Feeding supplemented mother milk during hospital stay improves neurodevelopment in preterm infants. Yet the composition of mother milk varies widely between subjects. The relationship between this variation and outcome is unknown.

OBJECTIVE

To determine whether the protein content in native breast milk (BM) correlates with 2-year infant outcome.

DESIGN

In a monocentric prospective observational study, LACTACOL, preterm infants born between 28 and 34 weeks of gestation, whose mothers decided to exclusively breastfeed, were enrolled during the first week of life. Samples of expressed breast milk obtained at several times of the day were pooled over a 24-h period, and such pool was used for macronutrient analysis, using mid-infrared analyzer. Age and Stages questionnaire (ASQ) was used to assess 2-year neurodevelopmental outcome. We analyzed the relationship between protein content in BM, and (i) infant neurodevelopment at 2-year (primary outcome), and (ii) growth until 2-year (secondary outcome).

RESULTS

138 infants were enrolled. The main analysis concerned 130 infants (including 40 twin infants) and 110 mothers with BM samples collected at week 3 after birth. Native BM samples were ranked in three tertiles of protein content (g/100 ml): 0.91 ± 0.09 (lower), 1.14 ± 0.05 (middle) and 1.40 ± 0.15 (upper); 48, 47 and 35 infants were ranked, respectively, in these three tertiles. Infants in the upper tertile were more often singleton (P = 0.012) and were born with lower birth weight and head circumference Z-scores (P = 0.005 and 0.002, respectively). Differences in weight and head circumference were no longer observed at 2-year. ASQ score at age 2 did not differ between the three tertiles (P = 0.780). Sensitivity analyses with imputations, including all 138 infants, confirmed the main analysis as well as analyses based on fortified BM as exposure.

CONCLUSIONS

Protein content of BM (native or fortified) is not associated with preterm infant neurodevelopment at 2-year. Higher protein content was associated with a lower birth weight.

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.

Percent Body Fat Content Measured by Plethysmography in Infants Randomized to High- or Usual-Volume Feeding after Very Preterm Birth

We measured percent body fat by air-displacement plethysmography in 86 infants born at <32 weeks of gestation randomized to receive either high-volume (180-200 mL/kg/day) or usual volume feeding (140-160 mL/kg/day). High-volume feeding increased percent body fat by ≤2% at 36 weeks of postmenstrual age (within a predefined range of equivalence). TRIAL REGISTRATION: ClincialTrials.gov: NCT02377050.

Effect of tactile/kinesthetic massage therapy on growth and body composition of preterm infants

Massage therapy (MT) improves growth parameters in preterm infants. The growth of lean mass rather than fat mass has been associated with better long-term outcomes. We aimed to study the effect of tactile/kinesthetic MT on growth and body composition parameters in preterm infants. Preterm (< 32 weeks gestation) infants were randomly assigned at corrected gestational age of 35 weeks to receive 3 consecutive, 15-min, sessions of MT over 5 days or routine care. Primary outcome was mean daily weight gain. Secondary outcomes included anthropometric measurements and body composition parameters assessed by dual X-ray absorptiometry (DXA) scan. Out of 218 infants screened, 86 were eligible and 60 infants (30 in each group) were recruited after parental consent. MT was associated with significant increase in daily weight gain [19.3 (10-34.3) versus 6.2 (2.5-18.4) g/day, p = 0.01] and growth velocity [12.5 (6-21) versus 3.6 (1.6-12.6) g/kg/d, p = 0.01] compared with routine care. Infants on MT showed significant increase in total body mass, fat mass (total/legs), lean mass (total/arms/legs/trunk), and bone mineral density (arms/legs/trunk) values compared with routine care group. In conclusions, MT improves growth quality as evident by increased total and regional lean masses, increased bone mineral density, and peripheral rather than central fat distribution. What is known on this subject? • Massage therapy (MT) for preterm infants leads to achievement of faster independent oral feeding, increased weight gain, less stress, less response to pain, less occurrence of sepsis, and shorter hospital stay. • Growth of lean mass rather than fat mass has been associated with better long-term outcomes. What this study adds? • Tactile/kinesthetic massage therapy in preterm infant is associated with improved growth parameters and anthropometric measures. • Tactile/kinesthetic massage therapy increased total body mass, fat mass (total/legs), lean mass (total/arms/legs/trunk), and bone mineral density (arms/legs/trunk) values.

Change in body composition of premature infants from parenteral nutrition discontinuation to term equivalent age

AIM

To compare body composition (BC) of premature infants at parenteral nutrition (PN) suspension and at term equivalent age (TEA).

METHODS

Body weight, fat mass (FM), fat free mass (FFM) and FM as % of body weight were measured in infants born at <32 gestational weeks by air-displacement plethysmography at PN suspension and at TEA in a tertiary level hospital. Z-scores were calculated for BC and anthropometric measurements. Nutritional and clinical data were obtained during hospital stay. BC, weight and length were measured at birth in a sample of infants born at term for comparison.

RESULTS

Thirty premature infants with birth weight of 1198 ± 270 g and gestational age of 29.8 ± 1.8 weeks were included. At PN suspension, at 32.6 ± 1.6 postconceptional weeks, FFM z-score was similar to FFM z-score measured at TEA, at 39.8 ± 0.7 postconceptional weeks (-1.43 ± 1.27 vs -1.78 ± 1.64, p = 0.26), while FM z-score and %FM z-score at PN suspension were lower than those measured at TEA (FM z-score: 0.23 ± 0.62 versus 2.04 ± 1.00, p < 0.0001 and %FM z-score: 0.66 ± 0.76 versus 2.08 ± 1.07, p < 0.0001). At TEA, weight and length of premature infants were similar to those of term-born infants (3130 ± 340 g vs 3350 ± 340 g; 49.2 ± 2.4 cm vs 50.2 ± 2.5 cm, respectively), but %FM was higher (21.3 ± 4.2% vs 9.2 ± 4.4%, p < 0.001); higher exclusive enteral caloric and protein intakes were associated with a decrease in FM z-scores from PN suspension to TEA.

CONCLUSION

In our sample of premature infants, fat free mass z-score was similar, while fat mass and % fat mass z-scores increased substantially from parenteral nutrition suspension to term-equivalent age. Nutritional intakes during exclusive enteral nutrition did not seem to contribute to such increase.

Body composition in very preterm infants before discharge is associated with macronutrient intake

Very preterm infants experience poor postnatal growth relative to intra-uterine growth rates but have increased percentage body fat (%fat). The aim of the present study was to identify nutritional and other clinical predictors of infant %fat, fat mass (FM) (g) and lean mass (LM) (g) in very preterm infants during their hospital stay. Daily intakes of protein, carbohydrate, lipids and energy were recorded from birth to 34 weeks postmenstrual age (PMA) in fifty infants born <32 weeks. Clinical illness variables and anthropometric data were also collected. Body composition was assessed at 34–37 weeks PMA using the PEA POD Infant Body Composition System. Multiple regression analysis was used to identify independent predictors of body composition (%fat, FM or LM). Birth weight, birth weight z-score and PMA were strong positive predictors of infant LM. After adjustment for these factors, the strongest nutrient predictors of LM were protein:carbohydrate ratios (102–318 g LM/0·1 increase in ratio, P = 0·006–0·015). Postnatal age (PNA) and PMA were the strongest predictors of infant FM or %fat. When PNA and PMA were accounted for a higher intake of energy (–1·41 to –1·61 g FM/kJ per kg per d, P = 0·001–0·012), protein (–75·5 to –81·0 g FM/g per kg per d, P = 0·019–0·038) and carbohydrate (–27·2 to –30·0 g FM/g per kg per d, P = 0·012–0·019) were associated with a lower FM at 34–37 weeks PMA. Higher intakes of energy, protein and carbohydrate may reduce fat accumulation in very preterm infants until at least 34–37 weeks PMA.

Nutrition, Illness and Body Composition in Very Low Birth Weight Preterm Infants: Implications for Nutritional Management and Neurocognitive Outcomes

Preterm infants have altered body composition compared to term infants, which impacts both neurodevelopment and metabolic health, but whether increased dietary intake during hospitalization, independent of illness, may improve body composition is unknown. This prospective, longitudinal study (n = 103) measured fat-free mass (FFM) and percent body fat (%BF) at discharge and four months corrected age for prematurity (CA) in very low birth weight (VLBW) preterm infants. Markers of illness and macronutrient intakes (protein and caloric) were recorded. Bayley Scales of Infant Development-III (BSID) were administered at 12 and 24 months of age in a subset of these infants (n = 66 and n = 50 respectively). Body composition z-scores were calculated using recently developed reference curves. Linear regression was used to test the associations between clinical factors and body composition z-scores, as well as z-scores and BSID scores. Increased calories and protein received in the first week after birth and protein intake throughout hospitalization were associated with increased FFM z-scores at discharge, but not with %BF z-scores. After adjustment for both early acute and chronic illness, associations of nutrient intake with FFM z-score remained unchanged. FFM z-scores at discharge were positively associated with scores on the BSID at 12 and 24 months CA. In conclusion, increased energy and protein intakes both early in hospitalization and across its entire duration are associated with higher FFM at discharge, a key marker for organ growth and neurodevelopment in the VLBW neonate. Optimizing caloric intake, irrespective of illness is critical for enhancing body composition, and by extension, neurodevelopmental outcomes for preterm infants.

Lean Tissue Deficit in Preterm Infants Persists up to 4 Months of Age: Results from a Swedish Longitudinal Study

BACKGROUND

At term-equivalent age, infants born prematurely are shorter, lighter and have more adipose tissue compared to term counterparts. Little is known on whether the differences in body composition persist in later age.

METHODS

We prospectively recruited 33 preterm infants (<32 weeks gestational age, mean gestational age 28.1 weeks) and 69 term controls. Anthropometry and body composition (air displacement plethysmography) were monitored up to 4 months of age. Nutrient intakes from preterm infants were collected from clinical records.

RESULTS

At 4 months of age preterm infants were lighter and shorter than term controls (mean weight-for-age z-score: -0.73 vs. 0.06, p = 0.001; mean length-for-age z-score: -1.31 vs. 0.29, p < 0.0001). The significantly greater percentage of total body fat seen in preterm infants at term-equivalent age (20.2 vs. 11.7%, p < 0.0001) was no longer observed at 4 months. A deficit of fat-free mass persisted until 4 months of age (fat-free mass at term-equivalent age: 2.71 vs. 3.18 kg, p < 0.0001; at 4 months: 4.3 vs. 4.78 kg, p < 0.0001). The fat mass index and fat-free mass index (taking length into account) did not differ between the groups. Nutrition had little effect on body composition. Higher protein intake at week 2 was a negative predictor of fat-free mass at discharge.

CONCLUSIONS

At 4 months corrected age, preterm infants were both lighter and shorter than term controls and the absolute fat-free mass deficit remained until this age. Little effect of nutrition on body composition was observed.

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.

Associations of Growth and Body Composition with Brain Size in Preterm Infants

OBJECTIVE

To assess the association of very preterm infants' brain size at term-equivalent age with physical growth from birth to term and body composition at term.

STUDY DESIGN

We studied 62 infants born at <33 weeks of gestation. At birth and term, we measured weight and length and calculated body mass index. At term, infants underwent air displacement plethysmography to determine body composition (fat and fat-free mass) and magnetic resonance imaging to quantify brain size (bifrontal diameter, biparietal diameter, transverse cerebellar distance). We estimated associations of physical growth (Z-score change from birth to term) and body composition with brain size, adjusting for potential confounders using generalized estimating equations.

RESULTS

The median gestational age was 29 weeks (range, 24.0-32.9 weeks). Positive gains in weight and body mass index Z-score were associated with increased brain size. Each additional 100 g of fat-free mass at term was associated with larger bifrontal diameter (0.6 mm; 95% CI, 0.2-1.0 mm), biparietal diameter (0.7 mm; 95% CI, 0.3-1.1 mm), and transverse cerebellar distance (0.3 mm; 95% CI, 0.003-0.5 mm). Associations between fat mass and brain metrics were not statistically significant.

CONCLUSIONS

Weight and body mass index gain from birth to term, and lean mass-but not fat-at term, were associated with larger brain size. Factors that promote lean mass accrual among preterm infants may also promote brain growth.

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.

Fat trajectory after birth in very preterm infants mimics healthy term infants

BACKGROUND

Infants born very preterm experience poor postnatal growth relative to intrauterine growth, but at term equivalent age, they have increased percentage body fat compared with infants born at term.

OBJECTIVES

The aim of this study was to assess body composition in very preterm infants born before 32 weeks postmenstrual age and to compare this with infants born at 32-36 weeks of gestation.

METHODS

Percentage fat, fat mass and fat-free mass were measured in 87 very preterm infants born <32 weeks of gestation and studied at 32-36 weeks and in 88 control infants born at 32-36 weeks of gestation and measured on days 2-5 postnatally.

RESULTS

At 32-36 weeks, very preterm infants were lighter and shorter, had significantly greater percentage fat and absolute fat mass and had a significantly lower absolute fat-free mass than the control group. The trajectory in percentage fat over increasing postnatal age in very preterm infants was closely aligned to that in term infants.

CONCLUSIONS

Infants born very preterm accumulate fat rapidly after birth and have a deficit in fat-free mass. Fat accumulation may be triggered by birth or associated events. If this rapid fat accretion is not taken into account, assessment of growth based on weight alone will underestimate the deficit in fat-free mass.

Comprehensive Preterm Breast Milk Metabotype Associated with Optimal Infant Early Growth Pattern

Early nutrition impacts preterm infant early growth rate and brain development but can have long lasting effects as well. Although human milk is the gold standard for feeding new born full-term and preterm infants, little is known about the effects of its bioactive compounds on breastfed preterm infants' growth outcomes. This study aims to determine whether breast milk metabolome, glycome, lipidome, and free-amino acids profiles analyzed by liquid chromatography-mass spectrometry had any impact on the early growth pattern of preterm infants. The study population consisted of the top tercile-Z score change in their weight between birth and hospital discharge ("faster grow", n = 11) and lowest tercile ("slower grow", n = 15) from a cohort of 138 premature infants (27⁻34 weeks gestation). This holistic approach combined with stringent clustering or classification statistical methods aims to discriminate groups of milks phenotype and identify specific metabolites associated with early growth of preterm infants. Their predictive reliability as biomarkers of infant growth was assessed using multiple linear regression and taking into account confounding clinical factors. Breast-milk associated with fast growth contained more branched-chain and insulino-trophic amino acid, lacto-N-fucopentaose, choline, and hydroxybutyrate, pointing to the critical role of energy utilization, protein synthesis, oxidative status, and gut epithelial cell maturity in prematurity.

Early body composition changes are associated with neurodevelopmental and metabolic outcomes at 4 years of age in very preterm infants

BACKGROUND

Very preterm (VPT) infants are at-risk for altered growth, slower speed of processing (SOP), and hypertension. This study assesses the relationship between postnatal body composition (BC), neurodevelopment (indexed by SOP), and blood pressure (BP) in VPT infants.

METHODS

Thirty-four VPT infants underwent weekly measurements and BC testing until discharge and post-discharge at 4 mos CGA and 4 yrs. At post-discharge visits, SOP was assessed using visual evoked potentials and the NIH Toolbox; BP was also measured.

RESULTS

In-hospital rate of weight, length and fat-free mass (FFM) gains were associated with faster SOP at 4 yrs. Higher rate of gains in weight and FFM from discharge to 4 mos CGA were associated with faster SOP at 4 mos CGA, while higher fat mass (FM) gains during the same time were positively associated with BP at 4 yrs. BC at 4 yrs nor gains beyond 4 mos CGA were associated with outcomes.

CONCLUSIONS

In VPT infants, early FFM gains are associated with faster SOP, whereas post-discharge FM gains are associated with higher BPs at 4 yrs. This shows birth to 4 mos CGA is a sensitive period for growth and its relation to neurodevelopmental and metabolic outcomes. Close monitoring and early nutritional adjustments to optimize quality of gains may improve outcomes.

Sex and gender differences in developmental programming of metabolism

BACKGROUND

The early life environment experienced by an individual in utero and during the neonatal period is a major factor in shaping later life disease risk-including susceptibility to develop obesity, diabetes, and cardiovascular disease. The incidence of metabolic disease is different between males and females. How the early life environment may underlie these sex differences is an area of active investigation.

SCOPE OF REVIEW

The purpose of this review is to summarize our current understanding of how the early life environment influences metabolic disease risk in a sex specific manner. We also discuss the possible mechanisms responsible for mediating these sexually dimorphic effects and highlight the results of recent intervention studies in animal models.

MAJOR CONCLUSIONS

Exposure to states of both under- and over-nutrition during early life predisposes both sexes to develop metabolic disease. Females seem particularly susceptible to develop increased adiposity and disrupted glucose homeostasis as a result of exposure to in utero undernutrition or high sugar environments, respectively. The male placenta is particularly vulnerable to damage by adverse nutritional states and this may underlie some of the metabolic phenotypes observed in adulthood. More studies investigating both sexes are needed to understand how changes to the early life environment impact differently on the long-term health of male and female individuals.

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.

Deficit of Fat Free Mass in Very Preterm Infants at Discharge is Associated with Neurological Impairment at Age 2 Years

Preterm infants have a deficit of fat-free mass accretion during hospitalization. This study suggests that z score of fat-free mass at discharge is associated with neurologic outcome (P = .003) at 2 years of age, independent of sex, gestational age, and birth weight z score. Interventions to promote quality of growth should be considered.

Can Basic Characteristics Estimate Body Composition in Early Infancy?

OBJECTIVES

Increasing evidence demonstrates that body composition in early life contributes to the programming of health later in life in both full-term and preterm infants. Given the important role of body composition, the increased availability of easy, noninvasive, and accurate techniques for its assessment has been recommended. The aim of the present study was to identify basic characteristics and anthropometric measurements that best correlate with body composition in infants.

METHODS

Anthropometric measurements and body composition assessed by air-displacement plethysmography were assessed either at birth or at term-corrected age in 1239 infants (654 full-term, 585 preterm). The associations of sex, GA (gestational age), and weight with FFM (fat-free mass) and FM (fat mass) adjusted by length (g/cm) were investigated by multiple linear regression models. Bland-Altman tests were performed, and an equation for calculating FFM was determined.

RESULTS

Preterm infants exhibited increased FM and reduced FFM compared with full-term infants (477.6 ± 204 vs 259.7 ± 147 g and 2583 ± 494 vs 2770 ± 364 g, respectively). GA, male sex, and weight were positively associated with FFM (r = 0.806, P < 0.0001; 6.1 g of average bias). GA and male sex were negatively associated with FM, whereas weight was positively associated with FM (r = 0.641, P < 0.0001; 4.9 g of average bias).

CONCLUSIONS

The assessment of body composition represents the criterion standard. When body composition assessment is not feasible, the equation based on sex, GA, and anthropometric measurements can be useful in predicting body composition in both full-term and preterm infants.

Is the body composition development in premature infants associated with a distinctive nuclear magnetic resonance metabolomic profiling of urine?

OBJECTIVE

Preterm infants' body composition at term-corrected age differs from that of term infants but appears to be similar at the age of 3 months. The aim of this study was to compare the metabolomic pattern of preterm infants at term and at 3 months with that of term infants and to determine its association with body composition development.

METHOD

We designed a pilot study. Growth and body composition were evaluated by an air displacement plethysmography system in 13 preterm infants and seven term newborns at term and at 3 months of corrected age. Urine samples were collected at the same time points and analysed by nuclear magnetic resonance.

RESULTS

At term-corrected age, preterm infants showed a higher fat mass percentage compared with that of term newborns, whereas at 3 months of corrected age, the body composition parameters were similar between the groups. At the first time point, nuclear magnetic resonance analysis showed a urinary increase in choline/phosphocholine, betaine and glucose in preterm infants. At the second time point, the preterm group exhibited a urinary increase in choline/phosphocholine and a decrease in betaine.

CONCLUSIONS

The increased urinary excretion of choline, a betaine precursor, could reflect a potential altered metabolism in preterm infants.

Anthropometry and Body Composition of Preterm Neonates in the Light of Metabolic Programming

The improved survival of preterm infants has led to increased interest regarding their health as adults. In the context of metabolic programming, the connection between perinatal and early postnatal nutrition and growth with health in later life has brought to the fore the role of catch-up growth during the first months of preterm infants' lives and its association with body fat and obesity in childhood or puberty. A state-of-the art review was conducted in order to assess the way catch-up is evaluated, in terms of timing and rate. Adequate growth is of major importance for neurodevelopment; however, it may compete with adiposity or metabolic health. Studies based on body composition assessment have given conflicting results as regards the effect of early versus late and rapid versus slow catch-up growth on later health, mainly attributed to the lack of established criteria and definitions. Given that adequate early nutrition is crucial for the neurodevelopment of preterm infants, further studies are needed on the role of catch-up growth in long-term outcome, using generally accepted qualitative and quantitative criteria.

Breast Milk Lipidome Is Associated with Early Growth Trajectory in Preterm Infants

Human milk is recommended for feeding preterm infants. The current pilot study aims to determine whether breast-milk lipidome had any impact on the early growth-pattern of preterm infants fed their own mother's milk. A prospective-monocentric-observational birth-cohort was established, enrolling 138 preterm infants, who received their own mother's breast-milk throughout hospital stay. All infants were ranked according to the change in weight Z-score between birth and hospital discharge. Then, we selected infants who experienced "slower" (n = 15, -1.54 ± 0.42 Z-score) or "faster" (n = 11, -0.48 ± 0.19 Z-score) growth; as expected, although groups did not differ regarding gestational age, birth weight Z-score was lower in the "faster-growth" group (0.56 ± 0.72 vs. -1.59 ± 0.96). Liquid chromatography-mass spectrometry lipidomic signatures combined with multivariate analyses made it possible to identify breast-milk lipid species that allowed clear-cut discrimination between groups. Validation of the selected biomarkers was performed using multidimensional statistical, false-discovery-rate and ROC (Receiver Operating Characteristic) tools. Breast-milk associated with faster growth contained more medium-chain saturated fatty acid and sphingomyelin, dihomo-γ-linolenic acid (DGLA)-containing phosphethanolamine, and less oleic acid-containing triglyceride and DGLA-oxylipin. The ability of such biomarkers to predict early-growth was validated in presence of confounding clinical factors but remains to be ascertained in larger cohort studies.

In Preterm Infants, Length Growth below Expected Growth during Hospital Stay Predicts Poor Neurodevelopment at 2 Years

BACKGROUND

In preterm infants, neonatal weight growth is associated with neurodevelopmental outcome but is a poor indicator of growth quality.

OBJECTIVE

The aim of this work was to measure the relationship between neonatal length growth and the 2-year neurological outcome in preterm infants.

METHODS

A total of 2,403 infants enrolled in the LIFT cohort with gestational age less than 34 weeks were studied. Neonatal observed length growth (OLG) was calculated as the change in length Z-score between birth and discharge. Expected length growth (ELG) was estimated based on gestational age, birth weight Z-score, birth length Z-score, gender, and observed neonatal weight growth. The difference between OLG and ELG (∆OLG-ELG) was calculated as OLG - ELG, and infants were ranked into 3 classes depending on their ∆OLG-ELG (≤-0.5, -0.49 to 0.49, ≥0.50 Z-score). We explored the relationship between ∆OLG-ELG and 2-year neurodevelopmental outcome (n = 2,036), and, in a subgroup (n = 85), between ∆OLG-ELG and body composition at discharge.

RESULTS

ELG was strongly predicted from the above-mentioned parameters (R2 = 0.73, p = 0.001). OLG correlated closely with gestational age (p = 0.001) but ∆OLG-ELG did not (p = 1.0). OLG was not associated with a 2-year nonoptimal outcome after adjustment for gestational age, but ∆OLG-ELG ≤-0.5 was; the crude and adjusted odds ratios were 1.63 and 1.56, respectively. ∆OLG-ELG correlated negatively with fat mass (R2 = 0.29, p = 0.006) before and after adjustment for gestational age.

CONCLUSION

∆OLG-ELG is a marker of neonatal growth that does not depend on gestational age, and may reflect quality of growth. A ∆OLG-ELG ≤-0.5 Z-score is associated with a higher risk for 2-year nonoptimal neurodevelopmental outcome.

Do anthropometric measures accurately reflect body composition in preterm infants?

BACKGROUND

Recent literature suggests that neonatal adiposity is predictive of later metabolic health, while neonatal lean mass is predictive of later cognitive function amongst preterm infants. Anthropometric indices that accurately reflect neonatal body composition could improve clinical care and aid future research, but their validity has not been systematically tested in preterm infants.

OBJECTIVE

To determine the weight/length indices that best reflect neonatal body composition in preterm infants.

METHODS

Weight and length were measured, and body composition (fat-free mass (FFM), fat mass (FM) and percent body fat (%BF)) was assessed using air-displacement plethysmography within 72 h of birth in 218 preterm infants. The best weight/length proxy for FFM, FM and %BF were those with the highest proportion variance explained (R² ) and lowest root mean square error (RMSE) in linear regression models.

RESULTS

Among all of the weight/length indices tested, weight/length² was the best proxy for %BF, but nonetheless exhibited very low variance explained (R²  = 0.27) and high prediction error (RMSE = 3.5% fat). Body weight unadjusted for length was strongly associated with FFM (R²  = 0.97).

CONCLUSIONS

No weight/length index accurately reflected %BF. Weight/length indices are not appropriate for assessment of relative adiposity in preterm infants near birth. What's known on this subject: Compared with term infants, preterm infants have increased fat mass and diminished fat-free mass upon hospital discharge. Early adiposity predicts later metabolic health, while early lean mass is predictive of later neurodevelopmental outcomes. Optimal anthropometric proxies for preterm body composition at birth are not established.

WHAT THIS STUDY ADDS

Weight is an adequate surrogate for lean mass at birth in preterm infants. There are no weight/length indices that accurately reflect neonatal adiposity at birth.

Advances in nutrition of the newborn infant

Nutrition of newborn infants, particularly of those born preterm, has advanced substantially in recent years. Extremely preterm infants have high nutrient demands that are challenging to meet, such that growth faltering is common. Inadequate growth is associated with poor neurodevelopmental outcomes, and although improved early growth is associated with better cognitive outcomes, there might be a trade-off in terms of worse metabolic outcomes, although the contribution of early nutrition to these associations is not established. New developments include recommendations to increase protein supply, improve formulations of parenteral lipids, and provide mineral supplements while encouraging human milk feeding. However, high quality evidence of the risks and benefits of these developments is lacking. Clinical trials are also needed to assess the effect on preterm infants of experiencing the smell and taste of milk, to determine whether boys and girls should be fed differently, and to test effects of insulin and IGF-1 supplements on growth and developmental outcomes. Moderate-to-late preterm infants have neonatal nutritional challenges that are similar to those infants born at earlier gestations, but even less high quality evidence exists upon which to base clinical decisions. The focus of research in nutrition of infants born at term is largely directed at new formula products that will improve cognitive and metabolic outcomes. Providing the most effective nutrition to preterm infants should be prioritised as an important focus of neonatal care research to improve long-term metabolic and developmental outcomes.

Estimation of Fat-free Mass at Discharge in Preterm Infants Fed With Optimized Feeding Regimen

OBJECTIVES

The purpose of the present study was to validate a previously calculated equation (E1) that estimates infant fat-free mass (FFM) at discharge using data from a population of preterm infants receiving an optimized feeding regimen.

METHODS

Preterm infants born before 33 weeks of gestation between April 2014 and November 2015 in the tertiary care unit of Croix-Rousse Hospital in Lyon, France, were included in the study. At discharge, FFM was assessed by air displacement plethysmography (PEA POD) and was compared with FFM estimated by E1. FFM was estimated using a multiple linear regression model.

RESULTS

Data on 155 preterm infants were collected. There was a strong correlation between the FFM estimated by E1 and FFM assessed by the PEA POD (r = 0.939). E1, however, underestimated the FFM (average difference: -197 g), and this underestimation increased as FFM increased. A new, more predictive equation is proposed (r = 0.950, average difference: -12 g).

CONCLUSIONS

Although previous estimation methods were useful for estimating FFM at discharge, an equation adapted to present populations of preterm infants with "modern" neonatal care and nutritional practices is required for accuracy.

Does Human Milk Modulate Body Composition in Late Preterm Infants at Term-Corrected Age?

(1) Background: Late preterm infants account for the majority of preterm births and are at risk of altered body composition. Because body composition modulates later health outcomes and human milk is recommended as the normal method for infant feeding, we sought to investigate whether human milk feeding in early life can modulate body composition development in late preterm infants; (2) Methods: Neonatal, anthropometric and feeding data of 284 late preterm infants were collected. Body composition was evaluated at term-corrected age by air displacement plethysmography. The effect of human milk feeding on fat-free mass and fat mass content was evaluated using multiple linear regression analysis; (3) Results: Human milk was fed to 68% of the infants. According to multiple regression analysis, being fed any human milk at discharge and at  term-corrected and being fed exclusively human milk at term-corrected age were positively associated with fat-free mass content(β = −47.9, 95% confidence interval (CI) = −95.7; −0.18; p = 0.049; β = −89.6, 95% CI = −131.5; −47.7; p < 0.0001; β = −104.1, 95% CI = −151.4; −56.7, p < 0.0001); (4) Conclusion: Human milk feeding appears to be associated with fat-free mass deposition in late preterm infants. Healthcare professionals should direct efforts toward promoting and supporting breastfeeding in these vulnerable infants.

Greater Early Gains in Fat-Free Mass, but Not Fat Mass, Are Associated with Improved Neurodevelopment at 1 Year Corrected Age for Prematurity in Very Low Birth Weight Preterm Infants

OBJECTIVE

This work investigates the relationship between early body composition changes and neurodevelopment at 1 year age corrected for prematurity (CA).

STUDY DESIGN

A prospective, longitudinal study to measure body composition weekly in 34 very low birth weight preterm infants using air displacement plethysmography, beginning when infants stabilized after birth until discharge. Neurodevelopmental testing (Bayley Scales of Infant Development-III) was performed at 12 months CA. Linear mixed effects models were used to obtain inpatient subject-specific changes in fat-free mass (FFM) and fat mass (FM), which were then used as predictors of Bayley subscale scores in subsequent linear regression models, adjusting for potential confounders. Protein and energy provision were calculated for the first week of life.

RESULTS

Greater FFM gains while inpatient were associated with improved cognitive and motor scores at 12 months CA (P = .002 for both). These relationships remained significant when adjusting for birth weight, gestational age, and intraventricular hemorrhage (P ≤ .05 for both). Similar analysis was performed for FM gains without significant findings. Increased provision of protein and calories during the first week of life was positively associated with FFM gains (P ≤ .01 for both), but not FM gains (P ≥ .2 for both), throughout hospitalization.

CONCLUSIONS

Increased FFM gains, but not FM gains, during hospitalization are associated with improved neurodevelopment at 12 months CA. As early FM gains may be associated with long-term risk, more research is needed to develop strategies that optimize FFM gains while minimizing FM gains in very low birth weight preterm infants.

Diminished growth and lower adiposity in hyperglycemic very low birth weight neonates at 4 months corrected age

OBJECTIVE

Characterize the relationship between neonatal hyperglycemia and growth and body composition at 4 months corrected age (CA) in very low birth weight (VLBW) preterm infants.

STUDY DESIGN

A prospective study of VLBW appropriate-for-gestation infants (N=53). All blood glucose measurements in the first 14 days and nutritional intake and illness markers until discharge were recorded. Standard anthropometrics and body composition via air displacement plethysmography were measured near term CA and 4 months CA. Relationships between hyperglycemia and anthropometrics and body composition were examined using multivariate linear regression.

RESULTS

Infants with >5 days of hyperglycemia were lighter (5345 vs 6455 g, P⩽0.001), shorter (57.9 vs 60.9 cm, P⩽0.01), had smaller occipital-frontal head circumference (39.4 vs 42.0 cm, P⩽0.05) and were leaner (percent body fat 15.0 vs 23.8, P⩽0.01) at 4 months CA than those who did not have hyperglycemia, including after correcting for nutritional and illness factors.

CONCLUSIONS

Neonatal hyperglycemia in VLBW infants is associated with decreased body size and lower adiposity at 4 months CA independent of nutritional deficit, insulin use and illness. Downregulation of the growth hormone axis may be responsible. These changes may influence long-term growth and cognitive development.

Antropometria e composição corporal de recém-nascidos pré-termo na idade gestacional e no peso equivalente ao termo

OBJETIVO: Analisar o crescimento e a composição corporal de recém-nascidos pré-termo na idade gestacional corrigida de termo e ao alcançarem um peso entre 3,0 e 3,5 kg. MÉTODOS: Estudo longitudinal, realizado no Instituto Fernandes Figueira, Rio de Janeiro, com 39 recém-nascidos pré-termo e que apresentaram muito baixo peso ao nascer. Medidas antropométricas e água corporal total foram avaliadas no primeiro, no sétimo e no dia da recuperação do peso de nascimento, na idade gestacional corrigida do termo e em torno de três semanas de idade gestacional corrigida (correspondente ao tempo de vida para alcançar um peso entre 3,0 e 3,5 kg). O grupo de referência foi constituído por 32 recém-nascidos a termo, adequados para a idade gestacional, avaliados no segundo dia de vida. Considerou-se restrição de crescimento o escore-Z menor do que -2 para peso, comprimento e perímetro cefálico. RESULTADOS: Na idade de termo, 71,8% dos recém-nascidos pré-termo apresentaram restrição do crescimento para peso, 61,5% para comprimento e 25,6% para perímetro cefálico. Com três semanas de idade gestacional corrigida, esses recém-nascidos apresentaram a prega cutânea tricipital e a circunferência abdominal estatisticamente maiores que o grupo de referência enquanto o comprimento e a porcentagem de água corporal total foram menores. CONCLUSÃO: Os recém-nascidos pré-termo apresentaram perfil antropométrico e de água corporal diferente dos recém--nascidos a termo, sugerindo acúmulo de gordura. Houve recuperação do crescimento entre a idade de termo e três semanas de idade corrigida, sendo mais evidente esse crescimento em relação ao perímetro cefálico e peso.

Early Protein Intake Is Associated with Body Composition and Resting Energy Expenditure in Young Adults Born with Very Low Birth Weight

BACKGROUND

Suboptimal nutrition during fetal life and early childhood may be important in early programming of health and disease. Preterm infants born with very low birth weight (VLBW; <1500 g) frequently receive inadequate neonatal nutrition; the long-term consequences are poorly known.

OBJECTIVE

We evaluated the association between early macronutrient intake and body composition in young adults born with VLBW.

METHODS

We collected comprehensive information on daily nutritional intake during the initial hospital stay for 127 participants of the Helsinki Study of Very Low Birth Weight Adults. We calculated mean daily intakes of energy, protein, fat, and carbohydrate during the first 9 wk of life. At the mean age of 22.5 y, the subjects underwent measurements of weight, height, body composition by dual-energy X-ray absorptiometry, and resting energy expenditure. The associations were examined by linear regression.

RESULTS

We found that energy, protein, and fat intakes during the first 3 wk of life, all below current recommendations, predicted adult body composition. When adjusted for sex, age, birth weight SD score, and gestational age, a 1 g · kg(-1) · d(-1) higher protein intake predicted 11.1% higher lean body mass (LBM) (95% CI: 3.7%, 18.9%) and 8.5% higher resting energy expenditure (REE) (95% CI: 0.2%, 17.0%). Among those born before 28 wk of gestation, the numbers were 22.5% (95% CI: 1.9%, 47.4%) for LBM and 22.1% (95% CI: 3.6%, 44.0%) for REE. Similar associations were seen with energy (P = 0.01, P = 0.05) and fat (P < 0.01, P = 0.03) but not with carbohydrate. Energy intake was also associated with BMI (P = 0.01) and fat intake with BMI (P < 0.01) and percentage body fat (P = 0.05). The results were little changed when adjusted for prenatal and postnatal characteristics.

CONCLUSIONS

At relatively low neonatal protein intake levels, additional protein intake is reflected in a healthier body composition, accompanied by a higher metabolic rate, in young adults born with VLBW 20 y earlier.

Boys who are born preterm show a relative lack of fat-free mass at 5 years of age compared to their peers

AIM

Prematurity is associated with features of metabolic syndrome in young adulthood. We investigated the body composition and blood pressure of children born preterm.

METHODS

A longitudinal, observational study was conducted with preterm infants who had a birth weight of <1500 g and a gestational age of <32 weeks. Growth and body composition were assessed by air displacement plethysmography at term equivalent age and at school age and were compared to those of 61 healthy, term breastfed subjects.

RESULTS

A total of 63 preterm infants were enrolled. At term equivalent age, growth and fat-free mass were lower in preterm infants than in term newborns, but fat mass was higher. At 5 years of age, children born preterm were still lighter and shorter than children born at term. When the results were analysed by gender, the fat-free mass index was lower in boys born preterm than in their peers (12.1 ± 1.1 versus 13.0 ± 1.0 kg/h(2) p < 0.005), whereas no difference was detected among girls. Diastolic blood pressure was higher in children born preterm than in children born at term (61.14 ± 7.8 vs 56.69 ± 8.2 mmHg, p = 0.009).

CONCLUSION

Boys born preterm showed a relative lack of fat-free mass at school age compared to their peers.