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

Correction: Accelerated weight gain, prematurity, and the risk of childhood obesity: A meta-analysis and systematic review

[This corrects the article DOI: 10.1371/journal.pone.0232238.].

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.

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.

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.

Non-Obese Type 2 Diabetes with a History of Being an Extremely Preterm Small-for-Gestational-Age Infant without Early Adiposity Rebound

Adiposity rebound (AR), which is defined as a situation in which the body mass index (BMI) starts to increase after infancy, is a predictive marker of future development of type 2 diabetes. The patient was a 20-year-old male. He was born at 28 gestational weeks with a birthweight of 642 g (−3.20 standard deviation, small-for-gestational age [SGA]). AR during early childhood or obesity in later childhood was not observed. At the onset of type 2 diabetes (20 years of age), his BMI, body fat percentage, and body fat mass were within normal ranges (20.4, 18.4% and 10.8 kg, respectively). However, his muscle mass was 44.7 kg, with low muscle mass of the trunk and upper limbs, which was lower than the standard reference, indicating that myogenic insulin resistance was involved in the development of non-obese type 2 diabetes. This case report describes a patient with no presentation of AR and obesity during childhood, who was born extremely preterm SGA, developed non-obese type 2 diabetes with low muscle mass. We suggest that patients born extremely preterm SGA should be carefully observed for the development of type 2 diabetes, even if they did not have AR in early childhood or had not become obese.

Neonatal and Preterm Infant Growth Assessment

The needs to assess preterm infant growth clinically differ from the needs to summarize growth for research. Clinically, growth assessments are used to understand individuals' growth relative to their individual genetic potential, morbidity status and nutrition care. Growth quantification for research purposes is used to quantify growth of groups using meaningful metrics. Historically, neonatology has lacked consistency in the use of growth metrics, over-used irrelevant categories and over-diagnosed growth failure. Understanding the numerous preterm infant expected growth patterns can help identify concerning growth.

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.

Critical examination of relationships between early growth and childhood overweight in extremely preterm infants

OBJECTIVES

To identify the prevalence and risk factors for childhood overweight and obesity (OWO) at 3-year corrected age in children born <1500 g <29 weeks gestation.

STUDY DESIGN

A multicentre retrospective cohort study for preterm infants admitted to neonatal intensive care units between 2001 and 2014.

RESULTS

Data were available for 911 (89.4%) of the 1019 infants who met the inclusion criteria. Of them, 22 (2.4%) had OWO. There were no associations between OWO and being small for gestational age (RR = 1.3, 95% confidence interval (CI): 0.3-5.4) or weight <10th percentile at 36 weeks (RR = 1.1, 95% CI: 0.4-2.8). OWO was associated with low maternal education (RR = 7.4, 95% CI: 2.1-26), maternal diabetes (RR = 5.2, 95% CI: 1.9-15) and neonatal brain injury (RR = 4.9, 95% CI: 1.8-14). Adjusting for concurrent child weight at 3 years of age resulted in an overadjustment bias.

CONCLUSION

Small size at birth or at 36 weeks gestation in extremely preterm infants is not associated with increased risk of early childhood overgrowth or obesity.

CLINICAL TRIAL REGISTRATION

NCT03064022.

Analysis of Factors Associated With Body Mass Index at Ages 18 and 36 Months Among Infants Born Extremely Preterm

IMPORTANCE

The development of neonatology has been associated with improved survival among infants born extremely preterm, and understanding their long-term outcomes is becoming increasingly important. However, there is little information on body mass index (BMI) among these children.

OBJECTIVE

To determine factors associated with BMI at ages 18 months and 36 months among infants born extremely preterm.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, multicenter cohort study was conducted using data from the Neonatal Research Network Japan database for 8838 infants born at gestational ages 23 to 28 weeks with data on BMI at 18 months and 36 months. Data were analyzed from April 2018 through June 2021.

EXPOSURES

BMI and BMI z score at ages 18 months and 36 months were regressed with gestational age, intrauterine growth restriction (IUGR) status, and complications during pregnancy and the neonatal period separately by presence of multiple pregnancy and sex.

MAIN OUTCOMES AND MEASURES

BMI and BMI z score at ages 18 months and 36 months.

RESULTS

Among 16 791 eligible infants born extremely preterm, 8838 infants were included in the analysis. There were 7089 infants born from single pregnancies (mean [SD] gestational age, 26.0 [1.6] weeks; 3769 [53.2%] boys; mean [SD] birth weight, 847 [228] g) and 1749 infants born from multiple pregnancies (mean [SD] gestational age, 26.3 [1.5] weeks; 903 [51.6%] boys; mean [SD] birth weight, 860 [217] g). In single pregnancies, every week of increased gestational age was associated with an increase in BMI of 0.21 (95% CI, 0.17-0.25) among boys and 0.20 (95% CI, 0.15-0.25) among girls at age 18 months and 0.21 (95% CI, 0.18-0.24) among boys and 0.21 (95% CI, 0.18-0.24) among girls at age 36 months. There was an interaction association between gestational age and IUGR among boys at age 36 months, with a decrease in the change associated with gestational age of 0.12 (95% CI, 0.05-0.19). Every week of increased gestational age in single pregnancies was associated with an increase in BMI z score of 0.14 (95% CI, 0.17-0.21) among boys and 0.17 (95% CI, 0.13-0.21) among girls at age 18 months and 0.19 (95% CI, 0.16-0.22) among boys and 0.17 (95% CI, 0.15-0.20) among girls at age 36 months. Among single pregnancies, IUGR was associated with a decrease in BMI among boys (0.59 [95% CI, 0.23-0.95]) and girls (0.75 [95% CI, 0.39-1.11]) and BMI z score among boys 0.85 [95% CI, 0.25-0.95)] and girls (0.67 [95% CI, 0.36-0.97] at age 18 months and BMI among boys (0.44 [95% CI, 0.17-0.18]) and girls (0.84 [95% CI, 0.55-1.12]) and BMI z score among boys (0.46 [95% CI, 0.21-0.71]) and girls (0.77 [95% CI, 0.53-1.01]) at age 36 months. In multiple pregnancies, IUGR was associated with a decrease in BMI z score at age 36 months among boys (0.26 [95% CI, 0.42-0.89]) and girls (0.29 [95% CI, 0.22-0.79]). In single pregnancies intraventricular hemorrhage (IVH) was associated with a decrease in BMI of 0.47 (95% CI, 0.21-0.73) among boys and 0.42 (95% CI, 0.13-0.71) among girls at age 18 months and 0.53 (95% CI, 0.32-0.74) among boys and 0.31 (95% CI, 0.07-0.54) among girls at age 36 months. IVH was associated with a decrease in BMI z score in single pregnancies of 0.63 (95% CI, 0.20-0.41) among boys and 0.35 (95% CI, 0.12-0.60) among girls at age 18 months and 0.53 (95% CI, 0.34-0.71) among boys and 0.30 (95% CI, 0.11-0.50) among girls at age 36 months. Similar associations were seen in multiple pregnancies.

CONCLUSIONS AND RELEVANCE

This study found that gestational age, the presence of IUGR and multiple pregnancy, and IVH complications were associated with infant BMI at ages 18 months and 36 months. These findings suggest that these complicating factors should be considered when setting growth targets and nutrition strategies for infants born extremely preterm.

Are small-for-gestational-age preterm infants at increased risk of overweight? Statistical pitfalls in overadjusting for body size measures

OBJECTIVE

The objective of this study is to analyze the effect of adjusting for body measures on the association between small for gestational age (SGA) and overweight at 3 years.

STUDY DESIGN

Data were obtained from the Preterm Infant Multicenter Growth Study (n = 1089). Logistic regression was used, to adjust for confounders with additional adjustments separately for weight and height at 21 months. Marginal structural models (MSMs) estimated the direct effect of SGA on overweight.

RESULTS

The crude and adjusted for confounders models yielded null associations between SGA and overweight. Adjusting for height yielded a positive association (odds ratio (OR): 2.31, 95% CI: 0.52-10.26) and adjusting for weight provided a significantly positive association (OR: 6.60, 95% CI: 1.10-37.14). The MSMs, with height and weight held constant, provided no evidence for a direct effect of SGA on overweight (OR: 0.83, 95% CI: 0.14-5.01, OR: 0.71, 95% CI: 0.18-2.81, respectively).

CONCLUSION

Adjusting for body measures can change the association between SGA and overweight, providing spurious estimates.

Associations of early nutrition with growth and body composition in very preterm infants: a prospective cohort study

BACKGROUND/OBJECTIVE

To investigate impacts of early postnatal macronutrient intakes on growth and body composition of preterm infants within the first 6 months.

SUBJECTS/METHODS

One hundred and thirty-three very preterm (VPT) and/or very low birth weight (VLBW) infants were consecutively included. Enteral and parenteral macronutrient intakes during the first 28 days were recorded and average daily intakes were calculated. Growth was measured at birth, term age, and 6 months of corrected age (CA). Body composition was examined by air displacement plethysmograph at term age and 6 months of CA. Associations of nutrient intakes with growth and body composition over time were analyzed using generalized estimating equation.

RESULTS

After adjusting for covariates, higher daily protein, lipid, and energy intake during the first 28 days was associated with higher weight at term age for every 1 g/kg/day increment of protein and lipid intake, and every 10 kcal/kg/day increment of energy intake was associated with 0.50 (95% CI 0.04, 0.96), 0.29 (95% CI 0.07, 0.51), and 0.27 (95% CI 0.10, 0.44) higher weight z-score, respectively. Higher protein intake was associated with lower z-score of fat mass (FM, β = -1.88, 95% CI -3.53, -0.23) and percentage of body fat (PBF, β = -2.18, 95% CI -3.98, -0.39) at 6 months of CA, but higher lipid and carbohydrate intake was associated with higher FM and PBF z-scores at 6 months of CA.

CONCLUSIONS

Macronutrient intakes during the first month of life have impacts on growth and body composition before 6 months of age. Higher daily protein intake is associated with a better growth and healthier body composition for VPT/VLBW infants.

Prematurity and body composition at 6, 18, and 30 years of age: Pelotas (Brazil) 2004, 1993, and 1982 birth cohorts

Background

We aimed to investigate the association between preterm birth and body composition at 6, 18, and 30 years of age using data from three population-based birth cohort studies.

Methods

Gestational age (GA), defined by the date of the last menstrual period (categorized in ≤33, 34–36, and ≥ 37 weeks), was gathered in the first 24-h after delivery for all live births occurring in the city of Pelotas, Brazil, in 2004, 1993 and 1982. Body composition was assessed by air-displacement plethysmography. Outcomes included fat mass (FM, kg), percent FM (%FM), FM index (FMI, kg/m²), fat-free mass (FFM, kg); percent FFM (%FFM), FFM index (FFMI, kg/m²), body mass index (BMI, kg/m² at 18 years in the 1993 cohort and 30 years in the 1982 cohort), and BMI Z-score (at 6 years in the 2004 cohort). We further explored the association of birth weight for GA with body composition indicators and BMI. Crude and adjusted linear regressions provided beta coefficients with 95% confidence intervals (95%CI).

Results

A total of 3036, 3027, and 3369 participants, respectively, from the 2004, 1993, and 1982 cohorts were analyzed. At 6 years, preterm boys (born at 34–36 weeks) presented lower adjusted mean of FM (β = − 0.80 kg, − 1.45;-0.16, p = 0.046), %FM (β = − 2.39%, − 3.90;-0.88, p = 0.008), FMI (β = − 0.70 kg/m², − 1.13;-0.27, p = 0.004) as well as lower FFM (β = − 0.4 kg, − 0.77; − 0.12, p = 0.010) and FFMI (β = − 0.3 kg/m², − 0.46;-0.10, p < 0.001), and BMI Z-score (β = − 0.69,; − 0.99;-0.40, p < 0.001); but higher %FFM (β = 2.4%, 0.87;-3.90, p = 0.008), when compared to boys born at term (≥37). At 30 years, FM (15.7 kg, 0.25;31.1, p = 0.102) was higher among males born at ≤33 weeks. No association was observed for females from the three cohorts and for 18-year-old males. The association of birth weight for GA with body composition and BMI was not significant in any cohort. At 6 years, SGA boys had lower FFMI than boys AGA.

Conclusions

Our results suggest that preterm birth is associated with decreased body fat and fat-free mass in childhood but higher fat mass in adulthood. Nevertheless, results were only significant for males. SGA boys also showed lower FFMI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10368-w.

Cardiovascular risk factors in those born preterm - systematic review and meta-analysis

Emerging evidence demonstrates a link between preterm birth (PTB) and later life cardiovascular disease (CVD). We conducted a systematic review and meta-analysis to compare conventional CVD risk factors between those born preterm and at term. PubMed, CINAHL, SCOPUS, and EMBASE databases were searched. The review protocol is registered in PROSPERO (CRD42018095005). CVD risk factors including systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index, lipid profile, blood glucose, and fasting insulin among those born preterm (<37 weeks' gestation) were compared with those born at term (≥37 weeks' gestation). Subgroup analyses based on gender, age, gestational at birth (<32 weeks' gestation and <28 weeks' gestation), and PTB associated with small for gestational age or average for gestational age were also performed. Fifty-six studies provided data on 308,987 individuals. Being born preterm was associated with 3.26 mmHg (95% confidence interval [CI] 2.08 to 4.44) higher mean SBP and 1.32 mmHg (95% CI: 0.61 to 2.04) higher mean DBP compared to being born at term. Subgroup analyses demonstrated that SBP was higher among (a) preterm compared to term groups from early adolescence until adulthood; (b) females born preterm but not among males born preterm compared to term controls; and (c) those born at <32 weeks or <28 weeks compared to term. Our meta-analyses demonstrate higher SBP and DBP among those born preterm compared to term. The difference in SBP is evident from early adolescence until adulthood.

Associations between Diet Quality and Body Composition in Young Children Born with Very Low Body Weight

BACKGROUND

Very low birth weight (VLBW; <1500 g) infants have increased adiposity and metabolic disease risk in adulthood. Limited evidence suggests low-quality childhood diets are a predisposing risk factor. Despite this, to our knowledge no study has yet examined associations between diet quality and body composition in VLBW individuals.

OBJECTIVE

The objective of this study was to determine associations between Healthy Eating Index-2010 (HEI-2010) scores and consumption of fruits/vegetables, added sugars, and macronutrients with body composition in 5.5-y-old children born VLBW. We hypothesized HEI-2010 scores were inversely associated with adiposity.

METHODS

This cohort study leveraged the 5.5-y follow-up to the Donor Milk for Improved Neurodevelopmental Outcomes randomized controlled trial. From June 2016 to July 2018, participants attended a follow-up visit at The Hospital for Sick Children, Canada, or were visited in their home. All 316 surviving infants from the trial were eligible, and the caregivers of 158 children (50%; 53% male) consented to follow-up. Diet quality (HEI-2010) and usual intake of fruits/vegetables, added sugars, and macronutrients were determined from two 24-h dietary recalls (ASA24). Linear regressions evaluated associations of diet with BMI (kg/m2) and waist circumference z-scores, total fat, fat-free mass (air displacement plethysmography), and skinfolds.

RESULTS

Mean ± SD age at follow-up was 5.7 ± 0.2 y, birth weight was 1013 ± 264 g, and gestational age was 27.9 ± 2.5 wk. Dietary data and BMI z-scores were available for all children; 123 completed air displacement plethysmography. HEI-2010 score was 58.2 ± 12.4 out of 100, and 27% of children had poor quality diets (scores ≤50). HEI-2010 scores were inversely associated with BMI z-score, but only in children with obese mothers. A 10-point increase in HEI-2010 score was associated with reduced BMI (β: -0.5 SD; 95% CI: -0.7, -0.2) and subscapular (-0.3 SD; 95% CI: -0.6, -0.06) z-scores.

CONCLUSIONS

Improving diet quality in children born VLBW with obese mothers may be an important strategy to prevent excess adiposity. This trial was registered at clinicaltrials.gov as Optimizing Mothers' Milk for Preterm Infants (OptiMoM) Program of Research: Study 1-Impact of Donor Milk at Kindergarten, NCT02759809.

Exercise capacity in children with bronchopulmonary dysplasia at school age

OBJECTIVE

To assess the exercise capacity, exercise habits, and lung function of preterm born children with bronchopulmonary dysplasia (BPD) compared to term born controls at school age.

METHODS

Cardiopulmonary exercise test (CPET) by cycle ergometer and pulmonary function test were performed in children with BPD (n = 42) and compared with a term born control group (n = 42). Daily activity, participation in sports and respiratory symptoms were assessed by questionnaire.

RESULTS

Children with BPD versus controls had significantly lower values for oxygen consumption (V̇O₂ [mL/min] 1442 ± 417 vs. 1766 ± 541), minute ventilation (VE [L/min] 48 ± 14.92 vs. 60 ± 18.33), and workload (W [watt] 96.1 ± 16.7 vs. 110.6 ± 17.2) at peak exercise and a lower anaerobic threshold (VO₂ AT [mL/min] 1183 ± 345 vs. 1382 ± 398). When corrected for weight, only for the workload (2.7 ± 0.5 vs. 3.1 ± 0.5, p = 0.0013) did significant differences persist. The forced expiratory volume in 1 s and forced expiratory flow between 25 and 75% of expired forced vital capacity were significantly reduced in the BPD group (p < 0.0001). Children with BPD have a higher risk of reporting difficulties in physical activity (OR 2.5) and of suffering from wheezing or shortness of breath while exercising (OR 2.5).

CONCLUSION

Compared to term born controls, children with BPD at school age show airflow obstruction, a lower workload in CPET, and more respiratory symptoms related to physical activity. The comparable oxygen consumption based on weight suggests a functionally normal alveolar compartment.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Accelerated weight gain, prematurity, and the risk of childhood obesity: A meta-analysis and systematic review

The purpose of this systematic review and meta-analysis of the literature was to analyze and evaluate the impact of prematurity and accelerated weight gain on the risk of childhood and adolescent obesity. CINAHL, Embase, PubMed, and Web of Science databases were searched until December 2019 which yielded 19 studies with a total of 169,439 children enrolled were systematically reviewed. The results revealed that preterm infants had a greater likelihood of childhood obesity (defined as BMI ≥95th percentile for age-sex), than term infants (OR = 1.19, 95% CI [1.13, 1.26]). However, no difference of childhood obesity was found between "small for gestational age"(SGA) and "appropriate for gestational age"(AGA) among preterms. Accelerated weight gain (defined as weight gain velocity during first two years after birth) significantly increased the likelihood of subsequent childhood obesity among preterms (aOR = 1.87, 95% CI [1.57, 2.231]). In conclusion, accelerated weight gain at infancy among preterm children may be a critical contributor to obesity in later life. Establishing optimal growth trajectories and timely referral to health care providers may be of clinical importance.

"Extrauterine growth restriction" and "postnatal growth failure" are misnomers for preterm infants

Preterm infants are increasingly diagnosed as having "extrauterine growth restriction" (EUGR) or "postnatal growth failure" (PGF). Usually EUGR/PGF is diagnosed when weight is <10th percentile at either discharge or 36-40 weeks postmenstrual age. The reasons why the phrases EUGR/PGF are unhelpful include, they: (i) are not predictive of adverse outcome; (ii) are based only on weight without any consideration of head or length growth, proportionality, body composition, or genetic potential; (iii) ignore normal postnatal weight loss; (iv) are usually assessed prior to growth slowing of the reference fetus, around 36-40 weeks, and (v) are usually based on an arbitrary statistical growth percentile cut-off. Focus on EUGR/PGF prevalence may benefit with better attention to nutrition but may also harm with nutrition delivery above infants' actual needs. In this paper, we highlight challenges associated with such arbitrary cut-offs and opportunities for further refinement of understanding growth and nutritional needs of preterm neonates.

Lean mass accretion in children born very low birth weight is significantly associated with estimated changes from sedentary time to light physical activity

BACKGROUND

Few studies have investigated how lifestyle is associated with body composition in children born very low birth weight (VLBW, <1500 g), a population at increased risk of obesity and metabolic syndrome in later life.

OBJECTIVES

Determine how time spent in physical activity, sedentary time, and sleep are associated with body composition in children born VLBW.

METHODS

In this prospective cohort study of 5.5-year-old children born VLBW, height, weight, body composition (skinfolds, air displacement plethysmography), and 7 days of movement data (logbooks and accelerometers) were collected.

RESULTS

Of 158 participants, 53% were male, and mean (SD) birth weight was 1013 (264) g. Only 52% achieved 60 minutes/day of moderate-to-vigorous physical activity, but 96% achieved sleep recommendations. Reallocating 30 minutes of sedentary time to light physical activity (LPA) was associated with 0.20 kg/m² (95% CI, 0.02 to 0.37) greater fat-free mass index. An equivalent inverse association was found when reallocating LPA to sedentary time. No associations were found for other movement behaviours.

CONCLUSIONS

Promoting LPA and reducing sedentary time may be an important strategy in reducing the elevated risk of obesity and metabolic syndrome amongst those born VLBW by supporting lean mass accretion. Funded by CIHR (FHG 129919) and SickKids Restracomp.

Premature birth was not associated with increased body fatness in four-year-old boys and girls

AIM

Premature birth is a worldwide problem and increases the risk of chronic disease later in life. Prematurely born infants may have a high percentage of body fat at term-equivalent age, but it is unclear if this characteristic is maintained in childhood. Therefore, we compared the size and body composition of four-year-old prematurely born children to such values of full-term controls.

METHODS

Between 2013 and 2015, we assessed weight, height, fat mass and fat-free mass, using air displacement plethysmography in 188 reasonably healthy prematurely born four-year-olds (98 boys).

RESULTS

At four years of age, prematurely born children (gestational weeks at birth: 23.3-36.9) tended to be lighter and shorter and to contain less fat mass and fat-free mass than did full-term controls. The gestational age at birth of the prematurely born children correlated positively and significantly (P < .05) with height, weight, body mass index, fat mass (kg, %), fat mass index and fat-free mass (kg) in girls but not in boys.

CONCLUSION

Prematurity was not associated with increased body fatness in our four-year-olds. Our findings are relevant in relation to previously published results showing that premature birth is associated with chronic disease later in life.

Adiposity and Fat-Free Mass of Children Born with Very Low Birth Weight Do Not Differ in Children Fed Supplemental Donor Milk Compared with Those Fed Preterm Formula

BACKGROUND

Many mothers of very-low-birth-weight (VLBW) infants (<1500 g) are unable to provide sufficient breast milk, and supplemental pasteurized donor human milk (donor milk) or preterm formula is required. The composition of donor milk differs from that of mother's milk and infants fed with donor milk often exhibit slower growth during hospitalization. The long-term impact of nutrient-enriched donor milk on growth, body composition, or blood pressure is unknown.

OBJECTIVE

We aimed to determine the effects of nutrient-enriched donor milk compared with preterm formula on growth, body composition, and blood pressure of children born preterm and with VLBW. Associations with in-hospital mother's milk intake were explored.

METHODS

This study was a follow-up of children at 5.5-y of age who participated in a randomized controlled trial evaluating the effect of nutrient-enriched donor milk (commencing at ≥120 mL·kg-1·d-1) or preterm formula fed as a supplement when mother's milk was unavailable. The trial intervention lasted 90 d or until hospital discharge, whichever occurred first. In this follow-up investigation, differences in total body fat percentage determined by using air displacement plethysmography (primary outcome), fat-free mass, skinfold thickness, waist circumference, BMI z scores, and blood pressure] were evaluated using linear regressions.

RESULTS

Of 316 surviving infants from the earlier trial, 158 (50%) participated in the current study (53% male). Mean ± SD birth weight and gestational age were 1013 ± 264 g and 27.9 ± 2.5 wk. The median (IQR) intervention period was 67.5 d (52.0-91.0 d). Mean ± SD age and BMI z score at follow-up were 5.7 ± 0.2 y and -0.3 ± 1.2. Supplemental nutrient-enriched donor milk, compared to preterm formula, was not associated with growth, body composition, or blood pressure. In-hospital mother's milk intake was positively associated with height z score at 5.5 y (β: 0.07; 95% CI: 0.004, 0.1; P = 0.04).

CONCLUSIONS

Supplemental nutrient-enriched donor milk and preterm formula during initial hospitalization results in comparable long-term growth and body composition in young children born VLBW. This trial was registered at clinicaltrials.gov as NCT02759809 and at isrctn.com as ISRCTN35317141.

Body Composition Using Air Displacement Plethysmography in Children With Intestinal Failure Receiving Long-Term Home Parenteral Nutrition

BACKGROUND

Children with intestinal failure (IF) are at risk of growth failure, but little information about body composition is available. Our aim was to assess body composition using air displacement plethysmography (ADP) and relate it to clinical and growth parameters.

METHODS

In this prospective descriptive observational 2-center cohort study, children aged 2-18 years receiving home parenteral nutrition (PN) for ≥6 months underwent ADP measurement. Fat mass index (FMI) and fat-free mass index (FFMI) standard deviation scores (SDSs) were calculated to normalize for small body size.

RESULTS

Twenty-one out of 22 children, median age 7.4 years, underwent successful ADP measurement after a median PN duration of 5.5 years. They were significantly lighter (median weight for age SDS -0.71, P = 0.004) and shorter (median height for age SDS -1.55, P < 0.001) than the normal population mean; 52% were growing below target height range. They had low FFMI (median SDS -1.53, P < 0.001) and high FMI (median SDS 0.80, P = 0.002). Weight for height and body mass index (BMI) were significantly associated with FFMI and BMI with FMI, but children with the same weight and height showed different body composition. In 13 patients with 1-year follow-up, growth and body composition did not change significantly.

CONCLUSION

Children with IF receiving long-term PN show lower FFM and higher FM than healthy children. Additionally, children with similar routine growth parameters showed different body composition. Further studies should evaluate the effect of a patient-tailored approach including physical activity and nutrition advice based on body composition.

Comparison of physical activity and body composition in a cohort of children born extremely preterm or with extremely low birth weight to matched term-born controls: a follow-up study

OBJECTIVES

To compare physical activity and body composition in a cohort of children born extremely preterm/extremely low birth weight (EP/ELBW) with term-born (TB) controls.

METHODS

A regional cohort of children born during 1999-2000 at gestational age <28 weeks or with birth weight <1000 g and their individually matched TB controls were examined in 2010-2011. Information on physical activity was obtained from parental questionnaires, and body composition was determined by anthropometry and dual X-ray absorptiometry.

RESULTS

Fifty-seven EP/ELBW and 57 TB controls were included at a mean age of 11.6 years. Compared with the TB children, the EP/ELBW-born children exercised less often (22% vs 44% exercised more than 3 days per week), had lower physical endurance and poorer proficiency in sports and play and were less vigorous during exercise (p<0.05). They also had lower values (mean; 95 % CI) for muscle mass (0.9; 0.3-1.5 kg), total bone mineral density z-score (0.30; 0.13-0.52 units) and fat mass ratio (0.14; 0.06-0.21 units). The association between physical activity and bone mineral and skeletal muscle mass accrual was significantly weaker for the EP/ELBW-born than the TB children.

CONCLUSIONS

The EP/ELBW-born children were less physically active, had signs of an unfavourable body composition with less muscle mass and lower bone mineral density than the TB controls. The association between physical activity and the measures of body composition was weaker in the group of EP/ELBW-born children.

Effect of foetal and infant growth and body composition on respiratory outcomes in preterm-born children

Body composition and growth outcomes of preterm-born subjects have been studied by many researchers. In general, preterm-born children have lower height and weight especially in infancy. Despite showing potential for catch-up growth, they continue to lag behind their term counterparts in adolescence and adulthood. The various methods of studying body composition and the differing gestations and ages at which it is assessed may go some way to explaining the inconsistent results observed in different studies. In addition, there is a paucity of data on the effects of foetal and infant growth and of body composition on later respiratory outcomes. In largely term-born subjects, foetal growth and growth trajectories appear to have differential effects on later respiratory outcomes. Early weight gain in infancy appears to be associated with increased respiratory symptoms in childhood but catch-up growth in infancy appears to be associated with possible improved lung function status.

Leptin and IGF-1 in relation to body composition and bone mineralization of preterm-born children from infancy to 8 years

OBJECTIVE

Preterm birth has been associated with altered body composition, especially increased fat mass (FM) and decreased bone mineralization, and leptin and IGF-1 have been suggested to be involved in the regulation of both. We aimed to study the interplay between leptin, IGF-1, FM and bone mineralization measured in infancy and childhood of children born preterm.

DESIGN

Observational study.

PATIENTS/SUBJECTS

Seventy-nine (40 boys) preterm-born children (gestational age ≤32 weeks and/or birth weight ≤1500 g) aged 8 years.

MEASUREMENTS

Serum leptin and IGF-1 were measured at term age, at 3- and 6-month corrected age (CA), and 8 years. Body composition (fat and lean mass) and bone parameters (bone area, mineral content and density) were measured by Dual-energy X-ray Absorptiometry (DXA) at term age, 6-month CA and 8 years.

RESULTS

Leptin was positively associated with FM at all time points and with bone parameters at term age and 6-month CA. IGF-1 was associated with body composition and bone density at most of the time points. Explained variation in bone mineralization increased significantly by adding bone area (BA) and height to the models.

CONCLUSIONS

During infancy and childhood, leptin and IGF-1 were associated with body composition in preterm-born children. In addition, leptin was associated with bone parameters in early infancy, but not in childhood. It is hypothesized that a complicated interplay between multiple pathways, which most likely changes over time, is involved in regulation of body composition and bone mineralization of preterm-born infants.

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.

An Attempt to Standardize the Calculation of Growth Velocity of Preterm Infants-Evaluation of Practical Bedside Methods

OBJECTIVE

To examine how well growth velocity recommendations for preterm infants fit with current growth references: Fenton 2013, Olsen 2010, INTERGROWTH 2015, and the World Health Organization Growth Standard 2006.

STUDY DESIGN

The Average (2-point), Exponential (2-point), Early (1-point) method weight-gains were calculated for 1,4,8,12, and 16-week time-periods. Growth references' weekly velocities (g/kg/d, gram/day and cm/week) were illustrated graphically with frequently-quoted 15 g/kg/d, 10-30 grams/day and 1 cm/week rates superimposed. The 15 g/kg/d and 1 cm/week growth velocity rates were calculated from 24-50 weeks, superimposed on the Fenton and Olsen preterm growth charts.

RESULTS

The Average and Exponential g/kg/d estimates showed close agreement for all ages (range 5.0-18.9 g/kg/d), while the Early method yielded values as high as 41 g/kg/d. All 3 preterm growth references were similar to 15 g/kg/d rate at 34 weeks, but rates were higher prior and lower at older ages. For gram/day, the growth references changed from 10 to 30 grams/day for 24-33 weeks. Head growth rates generally fit the 1 cm/week velocity for 23-30 weeks, and length growth rates fit for 37-40 weeks. The calculated g/kg/d curves deviated from the growth charts, first downward, then steeply crossed the median curves near term.

CONCLUSIONS

Human growth is not constant through gestation and early infancy. The frequently-quoted 15 g/kg/d, 10-30 gram/day and 1 cm/week only fit current growth references for limited time periods. Rates of 15-20 g/kg/d (calculated using average or exponential methods) are a reasonable goal for infants 23-36 weeks, but not beyond.

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.

Growth and body composition of preterm infants less than or equal to 32 weeks: Cohort study

BACKGROUND

Extremely preterm infants with weights less than the 10th percentile at discharge have a fat-free mass deficit.

AIM

To analyze the relationship of weight Z-scores less than -2SD at term age with fat-free mass and fat mass at term age and at 1 and 3 months of corrected age in very preterm infants.

STUDY DESIGN

COHORT STUDY: Subjects: Sixty-six preterm infants born before or at 32 weeks gestation with birth weight equal or greater than the 10th percentile for age were included at term age. They were classified according to weight Z-score as either: "term (-)" (n = 18) if weight Z-scores were less -2SD or "term (+)" (n = 48) if the weight Z-scores were equal or greater than -2SD at term age.

OUTCOME MEASURES

Growth and body composition by an air displacement plethysmography system and bioimpedance were assessed at term age and 1 and 3 months of corrected age.

RESULTS

Lower fat-free mass persisted up to 3 months in the "term (-)" group [4137 g (645) vs 4592 g (707), p < .01]. Fat mass was lower in the "term (-)" group at term and at 1 month but was similar at 3 months of corrected age [1295 g (774) vs 1477 g (782), p = .109]. Weight, length and head circumference Z-scores were lower in the "term (-)" group compared to those in the "term (+)" group.

CONCLUSIONS

The lean tissue deficits were maintained in the "term (-)" group while the differences in body fat percentage were not.

Body Composition Changes from Infancy to 4 Years and Associations with Early Childhood Cognition in Preterm and Full-Term Children

BACKGROUND

Infants born prematurely are at risk for neurodevelopmental complications. Early growth is associated with improved later cognition. The relationship of early proportionality and body composition with later cognition is not well established.

OBJECTIVES

To assess differences in fat-free mass and adiposity (fat mass, percent body fat) changes in preterm and full-term infants through preschool age and examine associations with early childhood cognition.

METHODS

This is a prospective, observational study in an appropriate for gestational age cohort of 71 patients (20 preterm and 51 full-term) from infancy through preschool age. Anthropometric and body composition measurements via air displacement plethysmography were obtained during infancy at term and 3-4 months (preterm corrected ages), and at 4 years. Cognitive testing occurred at 4 years. Associations of body composition changes between visits with cognitive function were tested using linear regression.

RESULTS

In the preterm group, higher term to 4-month corrected age percent body fat gains were associated with lower working memory performance (p = 0.01), and higher 4-month corrected age to 4-year fat-free mass gains were associated with higher full-scale IQ (p = 0.03) and speed of processing performance (p ≤ 0.02). In the full-term group, higher 4-month to 4-year fat mass gains were associated with lower full-scale IQ (p = 0.03).

CONCLUSIONS

Body composition gains during different time periods are associated with varying areas of cognitive function. These findings may inform interventions aimed at optimal growth.

Neonatal Morbidity Count Is Associated With a Reduced Likelihood of Achieving Recommendations for Protein, Lipid, and Energy in Very Low Birth Weight Infants: A Prospective Cohort Study

BACKGROUND

Serious morbidity may elevate nutrient requirements and affect adherence to feeding guidelines for very low birth weight (VLBW) infants. An understanding of factors affecting nutrient intakes of VLBW infants will facilitate development of strategies to improve nutrient provision. Our aim was to examine the impact of neonatal morbidity count on achieving recommended nutrient intakes in VLBW infants.

METHODS

VLBW infants enrolled in the Donor Milk for Improved Neurodevelopmental Outcomes trial (ISRCTN35317141, n = 363) were included. Serious morbidities and daily parenteral and enteral intakes were collected prospectively.

RESULTS

Median intakes of infants with and without ≥1 morbidity met protein recommendations (3.5-4.5 g/kg/d) by week 2, although not maintained after week 4. Infants with ≥1 morbidity (vs without) were 2 weeks slower in achieving lipid (4.8-6.6 g/kg/d; week 4 vs 2) and energy (110-130 kcal/kg/d; week 5 vs 3) and 1 week slower in achieving carbohydrate recommendations (11.6-13.2 g/kg/d; week 4 vs 3). Adjusted hazard ratios of first achieving recommendations on any given day in infants with any 1 or 2 morbidities were 0.6 (95% confidence interval [CI], 0.5-0.9) and 0.6 (0.4-0.9), respectively, for protein; 0.5 (0.4-0.7) and 0.3 (0.2-0.5) for lipid; and 0.5 (0.4-0.7) and 0.3 (0.2-0.4) for energy.

CONCLUSION

Morbidity is associated with a decreased likelihood of achieving lipid and consequently energy recommendations. This and the decline in protein intakes after the early neonatal period require further investigation to ensure optimal nutrition in this vulnerable population.

Body composition at birth and its relationship with neonatal anthropometric ratios: the newborn body composition study of the INTERGROWTH-21st project

BackgroundWe aimed to describe newborn body composition and identify which anthropometric ratio (weight/length; BMI; or ponderal index, PI) best predicts fat mass (FM) and fat-free mass (FFM).MethodsAir-displacement plethysmography (PEA POD) was used to estimate FM, FFM, and body fat percentage (BF%). Associations between FFM, FM, and BF% and weight/length, BMI, and PI were evaluated in 1,019 newborns using multivariate regression analysis. Charts for FM, FFM, and BF% were generated using a prescriptive subsample (n=247). Standards for the best-predicting anthropometric ratio were calculated utilizing the same population used for the INTERGROWTH-21^st Newborn Size Standards (n=20,479).ResultsFFM and FM increased consistently during late pregnancy. Differential FM, BF%, and FFM patterns were observed for those born preterm (34⁺⁰-36⁺⁶ weeks' gestation) and with impaired intrauterine growth. Weight/length by gestational age (GA) was a better predictor of FFM and FM (adjusted R²=0.92 and 0.71, respectively) than BMI or PI, independent of sex, GA, and timing of measurement. Results were almost identical when only preterm newborns were studied. We present sex-specific centiles for weight/length ratio for GA.ConclusionsWeight/length best predicts newborn FFM and FM. There are differential FM, FFM, and BF% patterns by sex, GA, and size at birth.

Body Composition Trajectories From Infancy to Preschool in Children Born Premature Versus Full-term

OBJECTIVES

The aim of the study was to longitudinally characterize infancy to preschool body composition trajectories and the association of early fat and fat-free mass gains with preschool age body composition in children born premature versus full-term.

METHODS

A cohort of appropriate-for-gestational age preterm (n = 20) and term (n = 51) infants were followed at 3 visits: "neonatal" visit 1 at 2 weeks of age for term and near term corrected age for preterm; "infancy" visit 2 at 3 to 4 months (preterm corrected age); "preschool" visit 3 at 4 years. Body composition via air displacement plethysmography and anthropometrics were measured at all visits. Tracking of infancy weight and body composition with preschool measurements was tested using Pearson partial correlation coefficients. Associations between serial body composition measurements were assessed using multiple linear regression.

RESULTS

Early differences in body composition between premature (mean gestational age 31.9 weeks, mean birth weight 1843 g) and full-term (mean gestational age 39.8 weeks) infants were not present at preschool age. Visit 1 body composition was not correlated with preschool measurements in the preterm infants. Visit 2 measurements were correlated with preschool measures. Fat-free mass accretion from visit 1 to visit 2 was positively associated with preschool lean mass (β = 0.038, P = 0.049) in preterm children, whereas fat accretion was not associated with preschool body composition.

CONCLUSIONS

Children born prematurely and full-term have similar body composition at preschool age. For preterms infancy fat-free mass gains, and not adiposity gains, are positively associated with preschool fat-free mass; this may be associated with lower risk of later obesity and adverse metabolic outcomes.