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

Association between preterm infant body composition in the first 3 months of life and preschool age: a cohort study

Compared with full-term infants, preterm infants have fat-free mass deficit in the first months of life, which increases the risk of metabolic diseases in the future. In this cohort of children born under 32-week gestational age or less than 1500 g, we aimed to evaluate the associations of body composition at term equivalent age and in the first 3 months of life with fat-free mass and fat mass percentage at 4 to 7 years of life. Body composition assessments by air displacement plethysmography and anthropometry were performed at term, at 3 months of corrected age, and at 4 to 7 years of age. Multiple linear regression analysis was used to observe the associations between body composition at these ages. At term, fat mass percentage showed a negative association and fat-free mass a positive association with fat-free mass at 4 to 7 years. The fat-free mass at 3 months and the gain in fat-free mass between term and 3 months showed positive associations with fat-free mass at 4 to 7 years.   Conclusion: Body composition at preschool age is associated with fat-free mass in the first 3 months of life, a sensitive period for the risk of metabolic diseases. What is Known: • Preterm infants have a deficit in fat-free mass and high adiposity at term equivalent age compared to full-term infants. • Fat-free mass reflects metabolic capacity throughout life and therefore is considered a protective factor against the risk of metabolic syndrome. What is New: •Fat-free mass gain in the first 3 months of corrected age is associated with fat-free mass at preschool and school ages. •The first 3 months of life is a sensitive period to the risk of metabolic diseases.

Race as social determinant of growth and body composition among infants born very preterm

OBJECTIVE

Racism leads to disparities in health outcomes. Our objective was to determine if black race was independently associated with differences in fat accretion at discharge in a large cohort of very preterm infants (32 weeks of gestation or less).

METHODS

De-identified demographic, anthropometric and body composition data were collected from seven neonatal units around the United States. Weight, length, and head circumference z-scores at birth and at the time of body composition assessment or hospital discharge were calculated.

RESULTS

The median gestational age and birthweight for this cohort (n = 888) were 29 weeks [IQR, 27-30] and 1167 g [SD, 354], respectively. The study population included 53% black preterm infants. Birthweight was lower in black preterm infants compared with white infants (1112 ± 334 g vs. 1228 ± 366 g; p < 0.0001). After adjusting for birthweight, gestational age, and birthweight-for-age z-score, black preterm infants had more weight gain (adjusted mean difference: 0.5 g/kg/day; p = 0.03) but not higher BF% z-scores at hospital discharge (adjusted mean: 1.2 vs. 1.3; p = 0.14) than white infants.

CONCLUSIONS

After adjusting for covariates, black race was associated with higher weight gain velocity but not higher BF% z-scores.

IMPACT

This study presents findings from a large-scale multicenter cohort. Racial differences were observed in birth weight and the rate of weight gain; however, these differences were not associated with dissimilarities in body composition outcomes. Understanding nutrition and growth outcomes across racial groups is necessary to combat racial disparities in the neonatal intensive care unit (NICU).

Insulin-like growth factor-1 infusion in preterm piglets does not affect growth parameters of skeletal muscle or tendon tissue

Prematurity has physical consequences, such as lower birth weight, decreased muscle mass and increased risk of adult-onset metabolic disease. Insulin-like growth factor 1 (IGF-1) has therapeutic potential to improve the growth and quality of muscle and tendon in premature births, and thus attenuate some of these sequalae. We investigated the effect of IGF-1 on extensor carpi radialis muscle and biceps brachii tendon of preterm piglets. The preterm group consisted of 19-day-old preterm (10 days early) piglets, treated with either IGF-1 or vehicle. Term controls consisted of groups of 9-day-old piglets (D9) and 19-day-old piglets (D19). Muscle samples were analysed by immunofluorescence to determine the cross-sectional area (CSA) of muscle fibres, fibre type composition, satellite cell content and central nuclei-containing fibres in the muscle. Tendon samples were analysed for CSA, collagen content and maturation, and vascularization. Gene expression of the tendon was measured by RT-qPCR. Across all endpoints, we found no significant effect of IGF-1 treatment on preterm piglets. Preterm piglets had smaller muscle fibre CSA compared to D9 and D19 control group. Satellite cell content was similar across all groups. For tendon, we found an effect of age on tendon CSA, and mRNA levels of COL1A1, tenomodulin and scleraxis. Immunoreactivity for elastin and CD31, and several markers of tendon maturation, were increased in D9 compared to the preterm piglets. Collagen content was similar across groups. IGF-1 treatment of preterm-born piglets does not influence the growth and maturation of skeletal muscle and tendon.

Early and exclusive enteral nutrition in infants born very preterm

OBJECTIVE

To characterise the effects of early and exclusive enteral nutrition with either maternal or donor milk in infants born very preterm (280/7-326/7 weeks of gestation).

DESIGN

Parallel-group, unmasked randomised controlled trial.

SETTING

Regional, tertiary neonatal intensive care unit.

PARTICIPANTS

102 infants born very preterm between 2021 and 2022 (51 in each group).

INTERVENTION

Infants randomised to the intervention group received 60-80 mL/kg/day within the first 36 hours after birth. Infants randomised to the control group received 20-30 mL/kg/day (standard trophic feeding volumes).

MAIN OUTCOME MEASURES

The primary outcome was the number of full enteral feeding days (>150 mL/kg/day) in the first 28 days after birth. Secondary outcomes included growth and body composition at the end of the first two postnatal weeks, and length of hospitalisation.

RESULTS

The mean birth weight was 1477 g (SD: 334). Half of the infants were male, and 44% were black. Early and exclusive enteral nutrition increased the number of full enteral feeding days (+2; 0-2 days; p=0.004), the fat-free mass-for-age z-scores at postnatal day 14 (+0.5; 0.1-1.0; p=0.02) and the length-for-age z-scores at the time of hospital discharge (+0.6; 0.2-1.0; p=0.002). Hospitalisation costs differed between groups (mean difference favouring the intervention group: -$28 754; -$647 to -$56 861; p=0.04).

CONCLUSIONS

In infants born very preterm, early and exclusive enteral nutrition increases the number of full enteral feeding days. This feeding practice may also improve fat-free mass accretion, increase length and reduce hospitalisation costs.

TRIAL REGISTRATION NUMBER

NCT04337710.

High protein intake on later outcomes in preterm children: a systematic review and meta-analysis

BACKGROUND

Appropriate protein intake is crucial for growth and development in children born preterm. We assessed the effects of high (HP) versus low protein (LP) intake on neurodevelopment, growth, and biochemical anomalies in these children.

METHODS

Randomised and quasi-randomised trials providing protein to children born preterm (<37 completed weeks of gestation) were searched following PRISMA guideline in three databases and four registers (PROSPERO registration CRD42022325659). Random-effects model was used for assessing the effects of HP (≥3.5 g/kg/d) vs. LP (<3.5 g/kg/d).

RESULTS

Data from forty-four studies (n = 5338) showed HP might slightly reduce the chance of survival without neurodisability at ≥12 months (four studies, 1109 children, relative risk [RR] 0.95 [95% CI 0.90, 1.01]; P = 0.13; low certainty evidence) and might increase risk of cognitive impairment at toddler age (two studies; 436 children; RR 1.36 [0.89, 2.09]; P = 0.16; low certainty evidence). At discharge or 36 weeks, HP intake might result in higher weight and greater head circumference z-scores. HP intake probably increased the risk of hypophosphatemia, hypercalcemia, refeeding syndrome and high blood urea, but reduced risk of hyperglycaemia.

CONCLUSIONS

HP intake for children born preterm may be harmful for neonatal metabolism and later neurodisability and has few short-term benefits for growth.

IMPACT STATEMENT

Planned high protein intake after birth for infants born preterm might be harmful for survival, neurodisability and metabolism during infancy and did not improve growth after the neonatal period. Protein intake ≥3.5 g/kg/d should not be recommended for children born preterm.

Expected and Desirable Preterm and Small Infant Growth Patterns

Adequate nutrition is necessary for achieving optimal growth and neurodevelopment. Growth is a natural and expected process that happens concomitantly with rapid advancements in neurodevelopment. Serial weight, length, and head circumference growth measures are essential for monitoring development, although identifying pathological deviations from normal growth can pose challenges. Appropriate growth assessments require considerations that a range of sizes for length, head circumference, and weight are expected and appropriate. Because of genetic differences and morbidities, there is a considerable overlap between the growth of healthy infants and those with growth alterations. Parents tend to be over-concerned about children who plot low on growth charts and often need reassurance. Thus, the use of terms such as "poor" growth or growth "failure" are discouraged when growth is approximately parallel to growth chart curves even if their size is smaller than specific percentiles. No specific percentile should be set as a growth goal; individual variability should be expected. An infant's size at birth is important information that goes beyond the common use of prognostic predictions of appropriate compared with small or large for gestational age. The lower the birthweight, the lower the nutrient stores and the more important the need for nutrition support. Compared to term infants, preterm infants at term-equivalent age have a higher percentage of body fat, but this diminishes over the next months. Current research findings support expert recommendations that preterm infants should grow, after early postnatal weight loss, similar to the fetus and then term-born infants, which translates to growth approximately parallel to growth chart curves. There is no need for a trade-off between optimum cognition and optimum future health. Each high-risk infant needs individualized nutrition and growth assessments. This review aims to examine infant growth expectations and messaging for parents of preterm and term-born infants within the broader causal framework.

The trajectory of head circumference and neurodevelopment in very preterm newborns during the first two years of life: a cohort study

OBJECTIVE

To evaluate the growth trajectory of head circumference and neurodevelopment, and to correlate head circumference with cognitive, language, and motor outcomes during the first two years.

METHOD

Prospective cohort study in a tertiary hospital including 95 newborns under 32 weeks or 1500 g. Neonates who developed major neonatal morbidities were excluded. The head circumference was measured at birth, at discharge, and at term-equivalent age, 1, 3, 5, 12, 18, and 24 months of corrected age, and the Bayley Scales (Bayley-III) were applied at 12, 18 and 24 months of corrected age to assess cognitive, language and, motor domains. Scores below 85 were classified as mild/moderate deficits and scores below 70 as severe deficits. The association between head circumference Z score and Bayley scores was assessed using Pearson's correlation. The study considered a significance level of 0.05.

RESULTS

There was a decrease of -0.18 in the head circumference Z score between birth and discharge and the catch-up occurred between discharge and 1 month (an increase of 0.81 in the Z score). There was a positive correlation between head circumference and Bayley scores at 18 months. There was also a positive correlation between head circumference at discharge and at 5 months with the three domains of the Bayley.

CONCLUSION

Serial measurements of head circumference provide knowledge of the trajectory of growth, with early catch-up between discharge and 1 month, as well as its association with neurodevelopment. Head circumference is therefore a valuable clinical marker for neurodevelopment, especially in very preterm newborns.

Metabolomic profiles of preterm small-for-gestational age infants

We aimed to characterize the metabolomic profiles in preterm small-for-gestational age (SGA) infants using cord blood. We conducted a gestational age (GA)-matched case-control study that included 30 preterm infants who were categorized into two groups: SGA infants, with a birth weight (BW) < 10th percentile for GA (n = 15) and non-SGA infants, with BW ≥ 10th percentile for GA (n = 15). SGA infants with chromosomal or genetic abnormalities were excluded. At birth, the umbilicus was double-clamped, and the cord blood was sampled from the umbilical vein. Metabolomic analyses were performed using capillary electrophoresis time-of-flight mass spectrometry. The median GA at birth was not significantly different between the two groups [SGA, 32 (26-36) weeks; non-SGA, 32 (25-35) weeks; p = 0.661)]. Of the 255 metabolites analyzed, 19 (7.5%) showed significant differences between SGA and non-SGA infants. There were significant reductions in the carnosine, hypotaurine, and S-methylcysteine levels in SGA infants as compared to non-SGA infants (p < 0.05). Carnosine was correlated with gestational age, BMI before pregnancy, body weight gain during pregnancy (p = 0.002, p = 0.023, and p = 0.020, respectively). In conclusion, preterm SGA infants have low levels of cord blood antioxidative- and antiglycation-related metabolites, making them vulnerable to oxidative stress.

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.

Prolonged renal function impairment in infants born during the peri-viable period: A retrospective longitudinal cohort study

BACKGROUND

The number of infants born during the peri-viable period who survive has been increasing.

AIM

To clarify renal function in infants from the time of birth during the peri-viable period until their due date.

STUDY DESIGN

This retrospective cohort study was conducted at a single center.

SUBJECTS

We reviewed the data of infants born at ≤28 weeks of gestation between 2018 and 2022 at our hospital. The infants were divided into the following groups: born at 22-24 weeks vs. 25-28 weeks (appropriate-for-gestational age [AGA] infants), and AGA infants vs. small-for-gestational age (SGA) infants (born at 22-28 weeks).

OUTCOME MEASURES

We compared the perinatal data and renal function of the infants from birth until their due date.

RESULTS

Eighty-one infants were included. Their serum creatinine, fractional excretion of sodium, and urine glucose levels were high or positive soon after birth but gradually improved. The urine albumin level was significantly higher among AGA infants born at 22-24 weeks, even at term equivalent age, than among those born at 25-28 weeks.

CONCLUSIONS

Persistent renal insufficiency was observed even around the term equivalent age in peri-viable infants. Follow-up data collected after the neonatal period should be investigated in these infants.

Pulsatile Leucine Administration during Continuous Enteral Feeding Enhances Skeletal Muscle Mechanistic Target of Rapamycin Complex 1 Signaling and Protein Synthesis in a Preterm Piglet Model

BACKGROUND

Continuous feeding does not elicit an optimal anabolic response in skeletal muscle but is required for some preterm infants. We reported previously that intermittent intravenous pulses of leucine (Leu; 800 μmol Leu·kg-1·h-1 every 4 h) to continuously fed pigs born at term promoted mechanistic target of rapamycin complex 1 (mTORC1) activation and protein synthesis in skeletal muscle.

OBJECTIVES

The aim was to determine the extent to which intravenous Leu pulses activate mTORC1 and enhance protein synthesis in the skeletal muscle of continuously fed pigs born preterm.

METHODS

Pigs delivered 10 d preterm was advanced to full oral feeding >4 d and then assigned to 1 of the following 4 treatments for 28 h: 1) ALA (continuous feeding; pulsed with 800 μmol alanine·kg-1·h-1 every 4 h; n = 8); 2) L1× (continuous feeding; pulsed with 800 μmol Leu·kg-1·h-1 every 4 h; n = 7); 3) L2× (continuous feeding; pulsed with 1600 μmol Leu·kg-1·h-1 every 4 h; n = 8); and 4) INT (intermittent feeding every 4 h; supplied with 800 μmol alanine·kg-1 per feeding; n = 7). Muscle protein synthesis rates were determined with L-[2H5-ring]Phenylalanine. The activation of insulin, amino acid, and translation initiation signaling pathways were assessed by Western blot.

RESULTS

Peak plasma Leu concentrations were 134% and 420% greater in the L2× compared to the L1× and ALA groups, respectively (P < 0.01). Protein synthesis was greater in the L2× than in the ALA and L1× groups in both the longissimus dorsi and gastrocnemius muscles (P < 0.05) but not different from the INT group (P > 0.10). Amino acid signaling upstream and translation initiation signaling downstream of mTORC1 largely corresponded to the differences in protein synthesis.

CONCLUSIONS

Intravenous Leu pulses potentiate mTORC1 activity and protein synthesis in the skeletal muscles of continuously fed preterm pigs, but the amount required is greater than in pigs born at term.

Effects of size at birth on health, growth and developmental outcomes in children up to age 18: an umbrella review

BACKGROUND

Size at birth, an indicator of intrauterine growth, has been studied extensively in relation to subsequent health, growth and developmental outcomes. Our umbrella review synthesises evidence from systematic reviews and meta-analyses on the effects of size at birth on subsequent health, growth and development in children and adolescents up to age 18, and identifies gaps.

METHODS

We searched five databases from inception to mid-July 2021 to identify eligible systematic reviews and meta-analyses. For each meta-analysis, we extracted data on the exposures and outcomes measured and the strength of the association.

FINDINGS

We screened 16 641 articles and identified 302 systematic reviews. The literature operationalised size at birth (birth weight and/or gestation) in 12 ways. There were 1041 meta-analyses of associations between size at birth and 67 outcomes. Thirteen outcomes had no meta-analysis.Small size at birth was examined for 50 outcomes and was associated with over half of these (32 of 50); continuous/post-term/large size at birth was examined for 35 outcomes and was consistently associated with 11 of the 35 outcomes. Seventy-three meta-analyses (in 11 reviews) compared risks by size for gestational age (GA), stratified by preterm and term. Prematurity mechanisms were the key aetiologies linked to mortality and cognitive development, while intrauterine growth restriction (IUGR), manifesting as small for GA, was primarily linked to underweight and stunting.

INTERPRETATION

Future reviews should use methodologically sound comparators to further understand aetiological mechanisms linking IUGR and prematurity to subsequent outcomes. Future research should focus on understudied exposures (large size at birth and size at birth stratified by gestation), gaps in outcomes (specifically those without reviews or meta-analysis and stratified by age group of children) and neglected populations.

PROSPERO REGISTRATION NUMBER

CRD42021268843.

The Influence of Early Nutrition on Neurodevelopmental Outcomes in Preterm Infants

Premature infants, given their limited reserves, heightened energy requirements, and susceptibility to nutritional deficits, require specialized care.

AIM

To examine the complex interplay between nutrition and neurodevelopment in premature infants, underscoring the critical need for tailored nutritional approaches to support optimal brain growth and function.

DATA SOURCES

PubMed and MeSH and keywords: preterm, early nutrition, macronutrients, micronutrients, human milk, human milk oligosaccharides, probiotics AND neurodevelopment or neurodevelopment outcomes. Recent articles were selected according to the authors' judgment of their relevance. Specific nutrients, including macro (amino acids, glucose, and lipids) and micronutrients, play an important role in promoting neurodevelopment. Early and aggressive nutrition has shown promise, as has recognizing glucose as the primary energy source for the developing brain. Long-chain polyunsaturated fatty acids, such as DHA, contribute to brain maturation, while the benefits of human milk, human milk oligosaccharides, and probiotics on neurodevelopment via the gut-brain axis are explored. This intricate interplay between the gut microbiota and the central nervous system highlights human milk oligosaccharides' role in early brain maturation.

CONCLUSIONS

Individualized nutritional approaches and comprehensive nutrient strategies are paramount to enhancing neurodevelopment in premature infants, underscoring human milk's potential as the gold standard of nutrition for 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.

Nutrient Composition of Donor Human Milk and Comparisons to Preterm Human Milk

BACKGROUND

Human milk is the preferred diet for very low birth weight (VLBW, <1500 g) infants. When mother's own milk is unable to meet the needs of VLBW infants, donor human milk (DHM) is the preferred alternative. Unfortunately, the composition of DHM remains elusive and no comparative studies between preterm human milk and DHM have been performed previously.

OBJECTIVES

We aimed to analyze the nutrient content of commercial pooled DHM and compare nutrient content in DHM with that of early and mature preterm human milk.

METHODS

We analyzed nutrient content in 15 DHM samples provided from 7 commercial milk banks including calories, carbohydrate, fat, protein, sodium, chloride, potassium, zinc, calcium, phosphorus, magnesium, and vitamin D and compared each nutrient to early (7 d of life) and mature (28 d of life) preterm human milk samples (n = 28-36 per nutrient, gestational age = 28 ± 3 wk). Protein-to-energy ratio and carbohydrate-to-nonprotein energy ratio were calculated for each sample and compared.

RESULTS

Mean values for all macro- and micronutrients in DHM are reported. In comparison to early or mature preterm human milk, DHM had significantly lower protein, sodium, chloride, potassium, and zinc content. Calorie, carbohydrate, calcium, phosphorus, magnesium, and vitamin D content did not differ statistically between DHM and early or mature preterm human milk. Fat content was modestly lower in early but not mature human milk when compared with DHM.

CONCLUSIONS

We provide mean values for several macro- and micronutrients for DHM and identify key differences between DHM and preterm human milk, which may be considered when designing human milk-based feeding plans. This study was registered at clinicaltrials.gov as NCT05742815.

Early Human Milk Fortification in Infants Born Extremely Preterm: A Randomized Trial

OBJECTIVES

Enteral nutrition with unfortified human milk during the first 2 postnatal weeks often leads to cumulative protein and energy deficits among preterm infants. Fortified human milk administered soon after birth could increase fat-free mass (FFM) and improve growth in these infants.

METHODS

This was a masked, randomized trial. Starting on feeding day 2, extremely preterm infants 28 weeks or younger fed maternal or donor milk were randomized to receive either a diet fortified with a human-based product (intervention group) or a standard, unfortified diet (control group). This practice continued until the feeding day when a standard bovine-based fortifier was ordered. Caregivers were masked. The primary outcome was FFM-for-age z score at 36 weeks of postmenstrual age (PMA).

RESULTS

A total of 150 infants were randomized between 2020 and 2022. The mean birth weight was 795±250 g, and the median gestational age was 26 weeks. Eleven infants died during the observation period. The primary outcome was assessed in 105 infants (70%). FFM-for-age z scores did not differ between groups. Length gain velocities from birth to 36 weeks PMA were higher in the intervention group. Declines in head circumference-for-age z score from birth to 36 weeks' PMA were less pronounced in the intervention group.

CONCLUSIONS

In infants born extremely preterm, human milk diets fortified soon after birth do not increase FFM accretion at 36 weeks' PMA, but they may increase length gain velocity and reduce declines in head circumference-for-age z scores from birth to 36 weeks' PMA.

Handling misclassified stratification variables in the analysis of randomised trials with continuous outcomes

Many trials use stratified randomisation, where participants are randomised within strata defined by one or more baseline covariates. While it is important to adjust for stratification variables in the analysis, the appropriate method of adjustment is unclear when stratification variables are affected by misclassification and hence some participants are randomised in the incorrect stratum. We conducted a simulation study to compare methods of adjusting for stratification variables affected by misclassification in the analysis of continuous outcomes when all or only some stratification errors are discovered, and when the treatment effect or treatment-by-covariate interaction effect is of interest. The data were analysed using linear regression with no adjustment, adjustment for the strata used to perform the randomisation (randomisation strata), adjustment for the strata if all errors are corrected (true strata), and adjustment for the strata after some errors are discovered and corrected (updated strata). The unadjusted model performed poorly in all settings. Adjusting for the true strata was optimal, while the relative performance of adjusting for the randomisation strata or the updated strata varied depending on the setting. As the true strata are unlikely to be known with certainty in practice, we recommend using the updated strata for adjustment and performing subgroup analyses, provided the discovery of errors is unlikely to depend on treatment group, as expected in blinded trials. Greater transparency is needed in the reporting of stratification errors and how they were addressed in the analysis.

Extrauterine Growth Restriction: Need for an Accurate Definition

Neonates show considerable variation in growth that can be recognized through serial measurements of basic variables such as weight, length, and head circumference. If possible, measurement of subcutaneous and total body fat mass can also be useful. These biometric measurements at birth may be influenced by demographics, maternal and paternal anthropometrics, maternal metabolism, preconceptional nutritional status, and placental health. Subsequent growth may depend on optimal feeding, total caloric intake, total metabolic activity, genetic makeup, postnatal morbidities, medications, and environmental conditions. For premature infants, these factors become even more important; poor in utero growth can be an important reason for spontaneous or induced preterm delivery. Later, many infants who have had intrauterine growth restriction (IUGR) and are born small for gestational age (SGA) continue to show suboptimal growth below the 10th percentile, a condition that has been defined as extrauterine growth restriction (EUGR) or postnatal growth restriction (PNGR). More importantly, a subset of these growth-restricted infants may also be at high risk of abnormal neurodevelopmental outcomes. There is a need for well-defined criteria to recognize EUGR/PNGR, so that correctional steps can be instituted in a timely fashion.

Review: Nutritional regulation of muscle growth in neonatal swine

Despite advances in the nutritional support of low birth weight and early-weaned piglets, most experience reduced extrauterine growth performance. To further optimize nutritional support and develop targeted intervention strategies, the mechanisms that regulate the anabolic response to nutrition must be fully understood. Knowledge gained in these studies represents a valuable intersection of agriculture and biomedical research, as low birth weight and early-weaned piglets face many of the same morbidities as preterm and low birth weight infants, including extrauterine growth faltering and reduced lean growth. While the reasons for poor growth performance are multifaceted, recent studies have increased our understanding of the role of nutrition in the regulation of skeletal muscle growth in the piglet. The purpose of this review is to summarize the published literature surrounding advances in the current understanding of the anabolic signaling that occurs after a meal and how this response is developmentally regulated in the neonatal pig. It will focus on the regulation of protein synthesis, and especially the upstream and downstream effectors surrounding the master protein kinase, mechanistic target of rapamycin complex 1 (mTORC1) that controls translation initiation. It also will examine the regulatory pathways associated with the postprandial anabolic agents, insulin and specific amino acids, that are upstream of mTORC1 and lead to its activation. Lastly, the integration of upstream signaling cascades by mTORC1 leading to the activation of translation initiation factors that regulate protein synthesis will be discussed. This review concludes that anabolic signaling cascades are stimulated by both insulin and amino acids, especially leucine, through separate pathways upstream of mTORC1, and that these stimulatory pathways result in mTORC1 activation and subsequent activation of downstream effectors that regulate translation initiation Additionally, it is concluded that this anabolic response is unique to the skeletal muscle of the neonate, resulting from increased sensitivity to the rise in both insulin and amino acid after a meal. However, this response is dampened in skeletal muscle of the low birth weight pig, indicative of anabolic resistance. Elucidation of the pathways and regulatory mechanisms surrounding protein synthesis and lean growth allow for the development of potential targeted therapeutics and intervention strategies both in livestock production and neonatal care.

Individualized Fortification Based on Measured Macronutrient Content of Human Milk Improves Growth and Body Composition in Infants Born Less than 33 Weeks: A Mixed-Cohort Study

The optimal method for human milk (HM) fortification has not yet been determined. This study assessed whether fortification relying on measured HM macronutrient content (Miris AB analyzer, Upsala, Sweden) composition is superior to fortification based on assumed HM macronutrient content, to optimize the nutrition support, growth, and body composition in infants born at <33 weeks' gestation. In a mixed-cohort study, 57 infants fed fortified HM based on its measured content were compared with 58 infants fed fortified HM based on its assumed content, for a median of 28 and 23 exposure days, respectively. The ESPGHAN 2010 guidelines for preterm enteral nutrition were followed. Growth assessment was based on body weight, length, and head circumference Δ z-scores, and the respective growth velocities until discharge. Body composition was assessed using air displacement plethysmography. Fortification based on measured HM content provided significantly higher energy, fat, and carbohydrate intakes, although with a lower protein intake in infants weighing ≥ 1 kg and lower protein-to-energy ratio in infants weighing < 1 kg. Infants fed fortified HM based on its measured content were discharged with significantly better weight gain, length, and head growth. These infants had significantly lower adiposity and greater lean mass near term-equivalent age, despite receiving higher in-hospital energy and fat intakes, with a mean fat intake higher than the maximum recommended and a median protein-to-energy ratio intake (in infants weighing < 1 kg) lower than the minimum recommended.

Defining postnatal growth failure among preterm infants in Indonesia

Background

Postnatal growth failure (PGF) frequently occurred among preterm infants with malnutrition. The decline in a weight-for-age z-score of ≥1.2 has been proposed to define PGF. It was unknown whether this indicator would be useful among Indonesian preterm infants.

Methods

Infants of &lt;37 weeks of gestational age born between 2020 and 2021, both stable and unstable, were recruited for a prospective cohort study during hospitalization in the level III neonatal intensive care unit at the Cipto Mangunkusumo General Hospital, Jakarta, Indonesia. The prevalence of PGF as defined by a weight-for-age z-score of &lt;−1.28 (&lt;10th percentile) at discharge, a weight-for-age z-score of &lt;−1.5 (&lt;7th percentile) at discharge, or a decline in a weight-for-age z-score of ≥1.2 from birth till discharge was compared. The association between those PGF indicators with the preterm subcategory and weight gain was assessed. The association between the decline in a weight-for-age z-score of ≥1.2 with the duration to achieve full oral feeding and the time spent for total parenteral nutrition was analyzed.

Results

Data were collected from 650 preterm infants who survived and were discharged from the hospital. The weight-for-age z-score of &lt;−1.28 or &lt;−1.5 was found in 307 (47.2%) and 270 (41.5%) subjects with PGF, respectively. However, both indicators did not identify any issue of weight gain among subjects with PGF, questioning their reliability in identifying malnourished preterm infants. By contrast, the decline in a weight-for-age z-score of ≥1.2 was found in 51 (7.8%) subjects with PGF, in which this indicator revealed that subjects with PGF had an issue of weight gain. Next, a history of invasive ventilation was identified as a risk factor for preterm infants to contract PGF. Finally, the decline in a weight-for-age z-score of ≥1.2 confirmed that preterm infants with PGF took a longer time to be fully orally fed and a longer duration for total parenteral nutrition than the ones without PGF.

Conclusion

The decline in a weight-for-age z-score of ≥1.2 was useful to identify preterm infants with PGF within our cohort. This could reassure pediatricians in Indonesia to use this new indicator.

Body composition and bone mass among 5-year-old survivors of necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) affects the intestine of preterm infants. Preterm infants risk inadequate bone mineralization. This risk may increase if the intestinal uptake of minerals is affected after NEC.

METHODS

This is a study of growth, bone mineral density (BMD), bone mineral content (BMC), and body composition at 5 years of age among Swedish children born before gestational week 37 + 0 with a history of NEC, minimum stage IIA, compared to matched controls. Fifty children, 25 NEC cases and 25 controls, were examined with dual energy X-ray absorptiometry (DXA) and DXA with laser.

RESULTS

The NEC cases had lower weight, -1.3 SDS vs -0.7 SDS, a lower fat mass and fat percent, 23.4 vs 29.1%, compared to the controls. NEC cases had lower BMC total body head excluded, 355.6 g vs 416.7 g. BMD Z-scores were lower among NEC cases in total body head excluded, -0.7 vs -0.1, and in lumbar spine.

CONCLUSIONS

Preterm NEC survivors at 5 years of age had reduced growth, an altered body composition, and indications of a lower bone mass compared to matched controls. The study suggests that preterm infants diagnosed with NEC need special attention during childhood regarding growth and bone health.

IMPACT

A follow-up longitudinal study of growth, bone health, and body composition at 5 years of age among children born preterm with a history of NEC compared to matched controls. The NEC cases had lower weight than controls. NEC cases had an altered body composition with lower fat mass compared to controls. The DXA results showed that the NEC cases had lower bone mineral content and a tendency to lower bone mineral density. The study suggests that preterm infants diagnosed with NEC need special attention at follow-up regarding growth and bone health compared to preterm infants without NEC.

Regulation of skeletal muscle protein synthesis in the preterm pig by intermittent leucine pulses during continuous parenteral feeding

BACKGROUND

Extrauterine growth restriction is a common complication of preterm birth. Leucine (Leu) is an agonist for the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signaling pathway that regulates translation initiation and protein synthesis in skeletal muscle. Previously, we showed that intermittent intravenous pulses of Leu to neonatal pigs born at term receiving continuous enteral nutrition increases muscle protein synthesis and lean mass accretion. Our objective was to determine the impact of intermittent intravenous pulses of Leu on muscle protein anabolism in preterm neonatal pigs administered continuous parenteral nutrition.

METHODS

Following preterm delivery (on day 105 of 115 gestation), pigs were fitted with umbilical artery and jugular vein catheters and provided continuous parenteral nutrition. Four days after birth, pigs were assigned to receive intermittent Leu (1600 µmol kg-1  h-1 ; n = 8) or alanine (1600 µmol kg-1  h-1 ; n = 8) parenteral pulses every 4 h for 28 h. Anabolic signaling and fractional protein synthesis were determined in skeletal muscle.

RESULTS

Leu concentration in the longissimus dorsi and gastrocnemius muscles increased in the leucine (LEU) group compared with the alanine (ALA) group (P < 0.0001). Despite the Leu-induced disruption of the Sestrin2·GATOR2 complex, which inhibits mTORC1 activation, in these muscles (P < 0.01), the abundance of mTOR·RagA and mTOR·RagC was not different. Accordingly, mTORC1-dependent activation of 4EBP1, S6K1, eIF4E·eIF4G, and protein synthesis were not different in any muscle between the LEU and ALA groups.

CONCLUSION

Intermittent pulses of Leu do not enhance muscle protein anabolism in preterm pigs supplied continuous parenteral nutrition.

Enteral Nutrition in Preterm Infants (2022): A Position Paper From the ESPGHAN Committee on Nutrition and Invited Experts

OBJECTIVES

To review the current literature and develop consensus conclusions and recommendations on nutrient intakes and nutritional practice in preterm infants with birthweight <1800 g.

METHODS

The European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee of Nutrition (CoN) led a process that included CoN members and invited experts. Invited experts with specific expertise were chosen to represent as broad a geographical spread as possible. A list of topics was developed, and individual leads were assigned to topics along with other members, who reviewed the current literature. A single face-to-face meeting was held in February 2020. Provisional conclusions and recommendations were developed between 2020 and 2021, and these were voted on electronically by all members of the working group between 2021 and 2022. Where >90% consensus was not achieved, online discussion meetings were held, along with further voting until agreement was reached.

RESULTS

In general, there is a lack of strong evidence for most nutrients and topics. The summary paper is supported by additional supplementary digital content that provide a fuller explanation of the literature and relevant physiology: introduction and overview; human milk reference data; intakes of water, protein, energy, lipid, carbohydrate, electrolytes, minerals, trace elements, water soluble vitamins, and fat soluble vitamins; feeding mode including mineral enteral feeding, feed advancement, management of gastric residuals, gastric tube placement and bolus or continuous feeding; growth; breastmilk buccal colostrum, donor human milk, and risks of cytomegalovirus infection; hydrolyzed protein and osmolality; supplemental bionutrients; and use of breastmilk fortifier.

CONCLUSIONS

We provide updated ESPGHAN CoN consensus-based conclusions and recommendations on nutrient intakes and nutritional management for preterm infants.

Prematurity blunts protein synthesis in skeletal muscle independently of body weight in neonatal pigs

BACKGROUND

Postnatal growth failure in premature infants is associated with reduced lean mass accretion. Prematurity impairs the feeding-induced stimulation of translation initiation and protein synthesis in the skeletal muscle of neonatal pigs. The objective was to determine whether body weight independently contributes to the blunted postprandial protein synthesis.

METHODS

Preterm and term pigs that were either fasted or fed were stratified into quartiles according to birth weight to yield preterm and term groups of similar body weight; first and second quartiles of preterm pigs and third and fourth quartiles of term pigs were compared (preterm-fasted, n = 23; preterm-fed, n = 25; term-fasted, n = 21; term-fed, n = 21). Protein synthesis rates and mechanistic target of rapamycin complex 1 (mTORC1) activation in skeletal muscle were determined.

RESULTS

Relative body weight gain was lower in preterm compared to term pigs. Prematurity attenuated the feeding-induced increase in mTORC1 activation in longissimus dorsi and gastrocnemius muscles (P < 0.05). Protein synthesis in gastrocnemius (P < 0.01), but not in longissimus dorsi muscle, was blunted by preterm birth.

CONCLUSION

A lower capacity of skeletal muscle to respond adequately to feeding may contribute to reduced body weight gain and lean mass accretion in preterm infants.

IMPACT

This study has shown that the feeding-induced increase in protein synthesis of skeletal and cardiac muscle is blunted in neonatal pigs born preterm compared to pigs born at term independently of birth weight. These findings support the notion that preterm birth, and not low birth weight, impairs the capacity of skeletal and cardiac muscle to upregulate mechanistic target of rapamycin-dependent anabolic signaling pathways and protein synthesis in response to the postprandial increase in insulin and amino acids. These observations suggest that a blunted anabolic response to feeding contributes to reduced lean mass accretion and altered body composition in preterm infants.

Optimising growth in very preterm infants: reviewing the evidence

Infants born before 32 weeks' postmenstrual age are at a high risk of growth failure. International guidelines have long recommended that they match the growth of an equivalent fetus, despite the challenges posed by ex utero life and comorbidities of prematurity. Several groups have recently questioned the necessity or desirability of this target, shifting attention to aiming for growth which optimises important long-term outcomes. Specifically, recent research has identified the neurodevelopmental benefits of enhanced growth during the neonatal period, but work in term infant suggests that rapid growth may promote the metabolic syndrome in later life. In this context, defining a pattern of growth which optimises outcomes is complex, controversial and contested. Even if an optimal pattern of growth can be defined, determining the nutritional requirements to achieve such growth is not straightforward, and investigations into the nutritional needs of the very preterm infant continue. Furthermore, each infant has individual nutritional needs and may encounter a number of barriers to achieving good nutrition. This article offers a narrative review of recent evidence for the competing definitions of optimal growth in this cohort. It examines recent advances in the determination of macronutrient and micronutrient intake targets along with common barriers to achieving good nutrition and growth. Finally, key implications for clinical practice are set out and a recommendation for structured multidisciplinary management of nutrition and growth is illustrated.

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.

Use of Head and Chest Circumference Ratio as an Index of Fetal Growth Retardation in Preterm Infants

We evaluated the relationship between fetal growth in preterm babies using the head circumference (HC)/chest circumference (CC) ratio and other anthropometric parameters at birth and at school age. Data were collected from 187 very low birth weight (VLBW) children born at less than 30 weeks of gestational age (GA) at birth and at 6 years. We assessed the correlation between the HC/CC ratio and body weight (BW), body length (BL), and HC z-scores at birth, and BW, body height (BH), and body mass index (BMI) z-scores at 6 years. Multiple regression analysis showed that BW z-score, BL z-score, and HC z-score at birth were significantly associated with HC/CC at birth. The BMI z-score at 6 years was also significantly associated with HC/CC at birth. The HC/CC ratio at birth is a reliable parameter for evaluating fetal growth restriction and a possible predictor of physical growth in VLBW children.

Gestational age, intrauterine growth and body composition at 11 years of age

OBJETIVE

To assess the association of gestational age (GA) and intrauterine growth with body composition at 11 years of age.

METHOD

Analysis of data from the 2004 Pelotas birth cohort, whose outcomes were fat mass (FM, kg), fat mass index (FMI, kg/m2), fat-free mass (FFM, kg), fat-free mass index (FFMI, kg/m2) - measured by air displacement plethysmography - and body mass index for age (BMI/age, Z-score). The exposures of interest were the gestational index (GA) of infants born at less than 33 weeks, from 34 to 36 and from 37 to 41, and intrauterine growth categorized as small (SGA), adequate (AGA) and large (LGA) for gestational age. Analysis of variance was used to compare means and linear regression was used to assess the strength of association. The analyses were adjusted according to variables collected at birth, such as monthly family income, maternal characteristics - education, age, pre-gestational body mass index (BMI), weight gain during pregnancy, smoking during pregnancy, type of delivery, and parity - and adolescent characteristics - skin color and birth weight. For analysis, FM and FMI underwent logarithmic transformation due to data asymmetry.

RESULTS

A total of 3,401 adolescents were analyzed, including boys and girls born at less than 33 weeks, with lower FM and FFM means than those born at term. However, in the adjusted analyses, there was no association between GA and any of the outcomes in either sex. LGA boys had a 10.5% higher FMI (p = 0.026) and +0.3 BMI/age Z-score (p = 0.019) as compared to AGA boys, and LGA girls had +0.3 kg/m 2 of FFMI (p = 0.039) than AGA girls.

CONCLUSION

GA was not associated with body composition at 11 years of age. However, LGA boys had higher BMI and BMI/age Z-score, and LGA girls had higher FFMI than AGA girls.

Increased Circulating Cortisol After Vaginal Birth Is Associated With Increased FGF19 Secretion in Neonatal Pigs

The influence of birth modality (scheduled cesarean or spontaneous vaginal) on the development of the newborn has been a source of controversy in neonatology. The impact of cesarean vs vaginal birth on the development of bile acid and fibroblast growth factor 19 (FGF19) signaling is unknown. Our aim was to determine the effect of birth modality and gestational age (preterm vs term) on plasma hormone levels, bile acid pool distribution, expression of genes in the bile acid-FXR-FGF19 pathway, and plasma levels of FGF19 at birth and on day 3 of life in neonatal pigs. Four sows underwent cesarean delivery on gestation day 105 (n = 2) and 114 (n = 2; term = 115 days), and 2 additional sows were allowed to farrow at term (gestation days 112 and 118). Piglets were euthanized at birth (Term-Vaginal n = 6; Term-Cesarean n = 8; Preterm n = 10) for tissue and blood collection, and the remaining pigs received total parenteral nutrition then were fed enterally on day 3 (Term-Vaginal n = 8; Term-Cesarean n = 10; Preterm n = 8), before blood and tissue were collected. Piglets born vaginally had a markedly (30-fold) higher plasma FGF19 at birth than term pigs born via cesarean delivery, and 70-fold higher than preterm pigs (P < 0.001). However, distal ileum FGF19 gene expression was similar in all groups (P > 0.05). Plasma FGF19 positively correlated with plasma cortisol (r = 0.58; P < 0.05) and dexamethasone treatment increased ileal FGF19 expression in cultured pig tissue explants and human enteroids. Our findings suggest that exposure to maternal or endogenous glucocorticoids in the perinatal period may upregulate the development of the bile acid-FGF19 pathway.

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.

Effect of a Multi-Strain Probiotic on Growth and Time to Reach Full Feeds in Preterm Neonates

Background: The main nutritional goal for premature neonates is to achieve a postnatal growth rate that the neonate would have experienced in utero. Postnatal growth failure is, however, very common in very and extremely low birth weight neonates. The use of probiotics shows promising results in reducing the time for full feeds, as well as in increased weight gain. The optimal probiotic strain has, however, not been elucidated. The aim of the present study was to evaluate the difference in the growth and time to reach full feeds between the two treatment arms, using LabinicTM as a multi-strain probiotic and a placebo. Methods: We conducted a double-blind, placebo-controlled, randomized clinical trial investigating the effect of a multi strain probiotic (LabinicTM) on various outcomes in preterm neonates. The results on the time to reach full feeds and the growth will be discussed in this paper. A probiotic or placebo was given once daily to the neonates for 28 days. Weight and feeding volume were measured daily, and length and head circumference were measured weekly. Results: The probiotic group reached full feeds earlier 8.7 days; ± 2.0 than the placebo group 9.7 days; ±4.3 (p = 0.04) and regained their birthweight earlier than the placebo group 11.5 days ± 6.3 vs. 13.3 days ± 6.3 (p = 0.06). From day 21 onwards, the probiotic group showed a significantly greater crude gain in weight (p < 0.001) than the placebo group (estimated difference between the two groups day 21: 56.7 g and at day 28: 83.7 g. There was a significant improvement observed in the weight Z-score change in the probiotic group over the 28-day period. Conclusion: The use of a multi-strain probiotic (LabinicTM) shows great potential as a low-cost, low-risk intervention in reducing the time to reach full feeds as well as shortening the time to regain birthweight. The probiotic had an additional beneficial impact on Z-score change in weight potentially decreasing post-natal growth restriction.

The impact of an early intervention home-based program on body composition in preterm-born preschoolers with very low birth weight

Background and aims

Early child interventions focused on the family prevented neurodevelopmental and behavioral delays and can provide more knowledge regarding responsive feeding, thus creating learning opportunities to promote better quality nutrition and preventing failure to thrive. The aim is to verify the impact of a continuous program of early home-based intervention on the body composition of preschool infants who were born preterm with very low birth weight (VLBW).

Methods

This is a longitudinal analysis from a randomized controlled trial, including VLBW preterm children, born in a tertiary hospital in Southern Brazil and followed up at the high-risk institutional ambulatory clinic. Participants were divided into the intervention group (IG): skin-to-skin care with the mother (kangaroo care), breastfeeding policy, and tactile-kinesthetic stimulation by mothers until hospital discharge. Subsequently, they received a program of early intervention with orientation and a total of 10 home visits, independently from the standard evaluation and care that was performed following the 18 months after birth; conventional group (CG): standard care according to the routine of the newborn intensive care unit (NICU), which includes kangaroo care, and attending to their needs in the follow-up program. Body composition estimation was performed using bioelectrical impedance analyses (BIA), and physical activity and feeding practices questionnaires were evaluated at preschool age, as well as anthropometric measurements and biochemical analysis.

Results

Data of 41 children at 4.6 ± 0.5 years old were evaluated (CG n = 21 and IG n = 20). Body weight, height, body mass index, waist and arm circumferences, and triceps and subscapular skinfold did not differ between groups. The IG presented higher segmented fat-free mass (FFM) when compared to the CG (right arm FFM: 0.74 vs. 0.65 kg, p = 0.040; trunk FFM: 6.86 vs. 6.09 kg, p = 0.04; right leg FFM: 1.91 vs. 1.73 kg, p = 0.063). Interaction analyses showed that segmented FFM and FFM Index were associated with higher iron content in the IG. In the CG, interaction analyses showed that increased visceral fat area was associated with higher insulin resistance index.

Conclusion

An early intervention protocol from NICU to a home-based program performed by the mothers of VLBW preterm children of low-income families presents a small effect on FFM.

Body composition at 4 to 7 years of age in children born <32 weeks gestational age or 1500 g: A cohort study

BACKGROUND

Small for gestational age preterm infants show differences in body composition when compared to those appropriate for gestational age at term, which have consequences on metabolism.

AIM

To compare growth and body composition of children born small and appropriate for gestational age between 4 and 7 years.

METHOD

A Cohort of small and appropriate for gestational age infants <32 weeks or 1500 g were followed at term and 3 months corrected ages and at 4 to 7 years. Body composition assessment by air displacement plethysmography and anthropometry were performed at all moments. Differences between the two groups were assessed using t-student and Chi-square tests.

RESULTS

Ninety-four infants were included at term (26 small and 68 appropriate for gestational age); 88 at 3 months (24 small and 64 appropriate for gestational age) and 47 between 4 and 7 years (11 small and 36 appropriate for gestational age). At term, small for gestational age infants had lower fat-free mass, fat mass, weight and length compared with those appropriate for gestational age (p < 0.001). At 3 months, fat-free mass (grams) remained lower in small for gestational age group (p < 0.001). Between 4 and 7 years, body composition and anthropometry were similar between the groups.

CONCLUSION

Between 4 and 7 years, children born small and appropriate for gestational age had similar body composition. New long-term longitudinal studies are necessary to understand the influence of fat-free mass and fat mass in the first months of age on body composition throughout life.

Preterm birth and metabolic implications on later life: A narrative review focused on body composition

Preterm newborn infants are characterized by low body weight and lower fat mass at birth compared with full-term newborn neonates. Conversely, at term corrected age, body fat mass is more represented in preterm newborn infants, causing a predisposition to developing metabolic syndrome and cardiovascular diseases in later life with a different risk profile in men as compared with women. Postnatal growth is a complex change in anthropometric parameters and body composition. Both quantity and quality of growth are regulated by several factors such as fetal programming, early nutrition, and gut microbiota. Weight gain alone is not an optimal indicator of nutritional status as it does not accurately describe weight quality. The analysis of body composition represents a potentially useful tool to predict later metabolic and cardiovascular risk as it detects the quality of growth by differentiating between fat and lean mass. Longitudinal follow-up of preterm newborn infants could take advantage of body composition analysis in order to identify high-risk patients who apply early preventive strategies. This narrative review aimed to examine the state-of-the-art body composition among born preterm children, with a focus on those in the pre-school age group.

Associations of body composition with regional brain volumes and white matter microstructure in very preterm infants

OBJECTIVE

To determine associations between body composition and concurrent measures of brain development including (1) Tissue-specific brain volumes and (2) White matter microstructure, among very preterm infants at term equivalent age.

DESIGN

Prospective observational study.

SETTING

Single-centre academic level III neonatal intensive care unit.

PATIENTS

We studied 85 infants born <33 weeks' gestation.

METHODS

At term equivalent age, infants underwent air displacement plethysmography to determine body composition, and brain MRI from which we quantified tissue-specific brain volumes and fractional anisotropy (FA) of white matter tracts. We estimated associations of fat and lean mass Z-scores with each brain outcome, using linear mixed models adjusted for intrafamilial correlation among twins and potential confounding variables.

RESULTS

Median gestational age was 29 weeks (range 23.4-32.9). One unit greater lean mass Z-score was associated with larger total brain volume (10.5 cc, 95% CI 3.8 to 17.2); larger volumes of the cerebellum (1.2 cc, 95% CI 0.5 to 1.9) and white matter (4.5 cc, 95% CI 0.7 to 8.3); and greater FA in the left cingulum (0.3%, 95% CI 0.1% to 0.6%), right uncinate fasciculus (0.2%, 95% CI 0.0% to 0.5%), and right posterior limb of the internal capsule (0.3%, 95% CI 0.03% to 0.6%). Fat Z-scores were not associated with any outcome.

CONCLUSIONS

Lean mass-but not fat-at term was associated with larger brain volume and white matter microstructure differences that suggest improved maturation. Lean mass accrual may index brain growth and development.

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 outcome at 2 years using Fenton and Intergrowth-21st charts in infants less than 1500 g

INTRODUCTION

There is no consensus on which neonatal chart is best to use in very low birth weight (VLBW) infants. The aim of the study was to compare the Fenton 2013 and Intergrowth-21st (IW-21) charts based on their predictive ability for somatometry at 2 years, as well as to analyze factors related to short stature at 2 years.

MATERIAL AND METHODS

Cohort of children with VLBW born between 2002 and 2017. Association between neonatal somatometry (z-score by Fenton and IW-21) and risk of short stature (<-2 DS), head circumference <-2 DS and malnutrition at 2 years (BMI < -2 DS) was analyzed (WHO charts).

RESULTS

513 children with a mean gestational age of 30.05 ± 2.5 weeks were included. Birth and discharge weight z-score by Fenton and IW-21 were useful for predicting risk of short stature and malnutrition at 2 years (without differences in the AUC of the ROC curves). Weight z-score at discharge was also useful for predicting head circumference < -2 DS. At 2 years, prevalence of short stature, head circumference < -2 DS, and malnutrition was 17.2, 4.1, and 6.1%, respectively. Low weight for gestational age and length of stay were identified as independent risk factors for short stature at 2 years.

CONCLUSIONS

Discharge weight z-score is useful for predicting risk of short stature, malnutrition and head circumference < -2 DS at 2 years in very low birth weight children, with no statistical difference between using Fenton or IW-21 charts.

Sex differences in preterm nutrition and growth: the evidence from human milk associated studies

Sexual dimorphism of the fetus manifests itself even during pregnancy. Preterm births are more common in pregnancies with male fetuses. Intrauterine and postnatal growth nomograms are sex-specific. The human milk composition in term infants appears to be sex-specific. Early nutrition has sex-specific effects and neurodevelopmental outcomes. A large same-sex twin study suggests that a mother's own milk (MOM) provides sex-specific growth advantages probably related to the calibration of a mother's milk based on her newborn's sex. Formula composition does not vary with infant sex, which may be one reason why body composition data favors the use of MOM over formula. However, given the lack of data on this subject, we need more detailed information on how the sex-specific micronutrients in MOM influence infant well-being. We also need more information to ascertain the sex differences in infants' macronutrient requirements, such as whether preterm females have higher fat requirements and preterm males have higher protein requirements for optimal growth and neurodevelopmental outcomes. This information may also influence milk banking and the use of donor human milk (DBM). Further research may help us determine if we should provide sex-specific DBM to those preterm infants who cannot get their MOM.

Intestinal Inflammation is Significantly Associated With Length Faltering in Preterm Infants at Neonatal Intensive Care Unit Discharge

OBJECTIVE

The aim of the study was to assess intestinal inflammatory measures, urinary intestinal fatty acid-binding protein (IFABP), and fecal calprotectin (FC) by gestational age (GA) and postmenstrual age (PMA) and determine the association between intestinal inflammation and growth in preterm infants from birth to hospital discharge. We hypothesized that intestinal inflammation is associated with adverse growth in preterm infants.

METHODS

We assayed repeated measures of IFABP and FC in 72 hospitalized preterm infants (<34 weeks' gestation). We calculated weight and length z scores at birth and discharge using the Fenton growth reference. Associations between mean IFABP or FC, growth z scores at discharge, and growth faltering (weight or length z score difference <-0.8 from birth to discharge) were assessed using mixed linear and logistic regression models, adjusted for intrafamilial correlation and potential confounders: GA, sex, birth z score, race/ethnicity, and maternal age.

RESULTS

Mean IFABP was greater among infants born at earlier GA and decreased with increasing PMA. Mean FC did not vary by GA or PMA. Higher mean IFABP and FC were associated with lower discharge growth z scores and greater likelihood of growth faltering significant only for mean IFABP and discharge length z score (β = -0.353, 95% confidence interval [CI]: -0.704 to -0.002) and mean IFABP and length faltering (odds ratio [OR] 1.99, P = 0.018).

CONCLUSIONS

Intestinal inflammation, measured by IFABP, was associated with lower length z scores and length faltering at discharge. Interventions to prevent intestinal inflammation may improve linear growth among preterm infants.

Body Composition of Infants Born with Intrauterine Growth Restriction: A Systematic Review and Meta-Analysis

Intrauterine growth restriction (IUGR) may predispose metabolic diseases in later life. Changes in fat-free mass (FFM) and fat mass (FM) may explain this metabolic risk. This review studied the effect of IUGR on body composition in early infancy. Five databases and included studies from all countries published from 2000 until August 2021 were searched. Participants were IUGR or small-for-gestational age (SGA) infants, and the primary outcomes were FFM and FM. Eighteen studies met the inclusion criteria, of which seven were included in the meta-analysis of primary outcomes. Overall, intrauterine growth-restricted and SGA infants were lighter and shorter than normal intrauterine growth and appropriate-for-gestational age infants, respectively, from birth to the latest follow up. They had lower FFM [mean difference −429.19 (p = 0.02)] and FM [mean difference −282.9 (p < 0.001)]. The issue of whether lower FFM and FM as reasons for future metabolic risk in IUGR infants is intriguing which could be explored in further research with longer follow-up. This review, the first of its kind can be useful for developing nutrition targeted interventions for IUGR infants in future.

Growth Trajectories during the First 6 Years in Survivors Born at Less Than 25 Weeks of Gestation Compared with Those between 25 and 29 Weeks

We aimed to determine the differences in the growth trajectories of the youngest gestational survivors (<25 weeks’ gestation) up to 6 years of age compared to those of older gestational ages. Preterm infants were divided into two groups: 22−24 weeks’ gestation (male (M) 16, female (F) 28) and 25−29 weeks’ gestation (M 84, F 59). Z-scores of body weight (BW), body length (BL), and body mass index (BMI) were derived from Japanese standards at 1, 1.5, 3, and 6 years of corrected age. Comparisons between the two groups by sex were made using the Wilcoxon test and linear regression analysis to examine the longitudinal and time-point associations of anthropometric z-scores, the presence of small for gestational age (SGA), and the two gestational groups. BW, BL, BMI, and z-scores were significantly lower in the 22−24 weeks group at almost all assessment points. However, there were no significant differences in BW, BL, BMI, and z-scores between the two female groups after 3 years. BMI z-scores were significantly associated with the youngest gestational age and the presence of SGA at all ages in males, but not in females. The youngest gestational age had a greater influence in males on the z-score of anthropometric parameters up to 6 years of age.

Racial differences in growth rates and body composition of infants born preterm

OBJECTIVE

To evaluate racial disparities in weight gain velocity and body composition among preterm infants.

STUDY DESIGN

This observational study analyzed race differences in fat-free mass (FFM), fat mass (FM), percent body fat (%BF), and weight gain at discharge of infants born at 25-32 weeks of gestation.

RESULTS

No racial differences in FFM, FM and %BF measurements were found between black and white preterm infants after adjusting for birth weight, gestational age, and the presence/absence of breastfeeding (n = 143). Black infants born preterm had lower birthweights and higher weight gain from birth to discharge in unadjusted and adjusted models (13 ± 3 vs. 11 ± 3 g/kg/day; <0.001).

CONCLUSION

Black infants had higher weight gain from birth to discharge, but comparable body composition measurements at discharge. More research is needed to understand contributing factors and long-term implications of this finding.

Association between neonatal malnutrition and bronchopulmonary dysplasia in very low-birth-weight infants: A propensity score-matched analysis

OBJECTIVE

To investigate the relationship between the nutrition status of infants with bronchopulmonary dysplasia (BPD) at the first 4 weeks of life and the likelihood of developing neonatal malnutrition.

METHODS

A total of 1064 infants were divided into a BPD group and a non-BPD group. After propensity score matching, there were 282 infants in each group. Infants were further divided into a neonatal malnutrition （NM） group and a well-nourished （WN） group. Clinical factors, nutrition intake, and growth parameters were collected and analyzed. Multivariate logistic regression model was used to determine the factors associated with neonatal malnutrition.

RESULTS

1. Compared with infants in the non-BPD group, the infants in BPD group had more fluid intake and lower calorie and protein intake after the second week, longer invasive ventilation time, and longer time to total oral feeding and parenteral nutrition (PN), and the difference was more significant in NM infants than in WN infants (P < 0.05). 2. The weight/length, body mass index, triponderal mass index, and weight gain velocity in the BPD group were significantly lower than in the non-BPD group (P < 0.05) and lower in NM infants than in WN ones (P < 0.05). 3. Multivariable system regression analysis showed that invasive ventilation time, lipid intake in week 4, time to reach full feeding, and duration of PN were independent risk factors for NM.

CONCLUSION

Enhancing calorie and macronutrient intake, reducing invasive ventilation, and achieving full gastrointestinal feeding early may be effective measures to avoid malnutrition in infants with BPD.

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.

Metabolic-endocrine disruption due to preterm birth impacts growth, body composition, and neonatal outcome

Despite optimized nutrition, preterm-born infants grow slowly and tend to over-accrete body fat. We hypothesize that the premature dissociation of the maternal-placental-fetal unit disrupts the maintenance of physiological endocrine function in the fetus, which has severe consequences for postnatal development. This review highlights the endocrine interactions of the maternal-placental-fetal unit and the early perinatal period in both preterm and term infants. We report on hormonal levels (including tissue, thyroid, adrenal, pancreatic, pituitary, and placental hormones) and nutritional supply and their impact on infant body composition. The data suggest that the premature dissociation of the maternal-placental-fetal unit leads to a clinical picture similar to panhypopituitarism. Further, we describe how the premature withdrawal of the maternal-placental unit, neonatal morbidities, and perinatal stress can cause differences in the levels of growth-promoting hormones, particularly insulin-like growth factors (IGF). In combination with the endocrine disruption that occurs following dissociation of the maternal-placental-fetal unit, the premature adaptation to the extrauterine environment leads to early and fast accretion of fat mass in an immature body. In addition, we report on interventional studies that have aimed to compensate for hormonal deficiencies in infants born preterm through IGF therapy, resulting in improved neonatal morbidity and growth. IMPACT: Preterm birth prematurely dissociates the maternal-placental-fetal unit and disrupts the metabolic-endocrine maintenance of the immature fetus with serious consequences for growth, body composition, and neonatal outcomes. The preterm metabolic-endocrine disruption induces symptoms resembling anterior pituitary failure (panhypopituitarism) with low levels of IGF-1, excessive postnatal fat mass accretion, poor longitudinal growth, and failure to thrive. Appropriate gestational age-adapted nutrition alone seems insufficient for the achievement of optimal growth of preterm infants. Preliminary results from interventional studies show promising effects of early IGF-1 supplementation on postnatal development and neonatal outcomes.

Intermittent bolus feeding does not enhance protein synthesis, myonuclear accretion, or lean growth more than continuous feeding in a premature piglet model

Optimizing enteral nutrition for premature infants may help mitigate extrauterine growth restriction and adverse chronic health outcomes. Previously, we showed in neonatal pigs born at term that lean growth is enhanced by intermittent bolus compared with continuous feeding. The objective was to determine if prematurity impacts how body composition, muscle protein synthesis, and myonuclear accretion respond to feeding modality. Following preterm delivery, pigs were fed equivalent amounts of formula delivered either as intermittent boluses (INT; n = 30) or continuously (CONT; n = 14) for 21 days. Body composition was measured by dual-energy X-ray absorptiometry (DXA) and muscle growth was assessed by morphometry, myonuclear accretion, and satellite cell abundance. Tissue anabolic signaling and fractional protein synthesis rates were determined in INT pigs in postabsorptive (INT-PA) and postprandial (INT-PP) states and in CONT pigs. Body weight gain and composition did not differ between INT and CONT pigs. Longissimus dorsi (LD) protein synthesis was 34% greater in INT-PP than INT-PA pigs (P < 0.05) but was not different between INT-PP and CONT pigs. Phosphorylation of 4EBP1 and S6K1 and eIF4E·eIF4G abundance in LD paralleled changes in LD protein synthesis. Satellite cell abundance, myonuclear accretion, and fiber cross-sectional area in LD did not differ between groups. These results suggest that, unlike pigs born at term, intermittent bolus feeding does not enhance lean growth more than continuous feeding in pigs born preterm. Premature birth attenuates the capacity of skeletal muscle to respond to cyclical surges in insulin and amino acids with intermittent feeding in early postnatal life.NEW & NOTEWORTHY Extrauterine growth restriction often occurs in premature infants but may be mitigated by optimizing enteral feeding strategies. We show that intermittent bolus feeding does not increase skeletal muscle protein synthesis, myonuclear accretion, or lean growth more than continuous feeding in preterm pigs. This attenuated anabolic response of muscle to intermittent bolus feeding, compared with previous observations in pigs born at term, may contribute to deficits in lean mass that many premature infants exhibit into adulthood.