Use of a body proportionality index for growth assessment of preterm infants

Defining Body Mass Index Using Weight and Length for Gestational Age in the Growth Assessment of Preterm Infants at Birth

OBJECTIVE

 The objectives of this study were to describe (1) body mass indexes (BMIs) using weight and length for gestational age (GA) classifications, and (2) the additional information BMI, as a measure of body proportionality, provides for preterm infant growth assessment and care plans at birth.

STUDY DESIGN

 Birth weight, length, and BMI of 188,646 preterm infants (24-36 weeks gestation) admitted to U.S. neonatal intensive care units (Pediatrix Clinical Data Warehouse, 2013-2018) were classified (Olsen curves) as small, appropriate, or large for GA (SGA < 10th, AGA 10-90th, LGA > 90th percentile for GA, respectively). The distribution for the 27 weight-length-BMI combinations was described.

RESULTS

 At birth, most infants were appropriate for weight (80.0%), length (82.2%), head circumference (82.9%), and BMI (79.9%) for GA. Birth weight for GA identified approximately 20% of infants as SGA or LGA. Infants born SGA (or LGA) for both weight and length ("proportionate" in size) were usually appropriate for BMI (59.0% and 75.6%). BMI distinguished disproportionate weight for length in infants with SGA or LGA weight at birth (58.3%, 49.9%). BMI also identified 11.4% of AGA weight infants as small or large for BMI ("disproportionate" in size) at birth; only using weight for GA missed these underweight/overweight for length infants.

CONCLUSION

 The unique, additional information provided by birth BMI further informs individualized preterm infant growth assessment by providing an assessment of an infant's body proportionality (weight relative to its length) in addition to the routine assessment of weight, length, and head circumference for GA and may better inform care plans and impact outcomes.

KEY POINTS

· Most preterm infants were born AGA for all growth measures.. · AGA weight infants may be under- or overweight for length.. · BMI distinguished body disproportionality in SGA/LGA infants.. · Recommend BMI assessed along with weight, length and head.. · Further research on BMI in preterm infants is needed..

Differences When Classifying Small for Gestational Age Preterm Infants According to the Growth Chart Applied

OBJECTIVE

 Consensus around the ideal chart to classify preterm babies is scant. It is particularly relevant in small for gestational age (SGA) infants due to its clinical and therapeutic implications. The aim of the study was to compare Olsen, Intergrowth-21st, and Fenton growth charts, regarding the classification at birth and incidence of SGA preterm infants.

STUDY DESIGN

 Retrospective study of 529 preterm infants ≤ 32 weeks of gestational age. Birth weight Z-score was calculated applying the three growth charts and ponderal index (PI) was also estimated. Incidence of SGA (birth weight < 10th percentile) and clinical outcome were compared according to the chart used.

RESULTS

 Incidence of SGA was significantly higher (p < 0.001) with Olsen (101 cases, 19.1%) compared with Intergrowth-21st (75 cases, 14.2%) and Fenton (53 cases, 10%). Differences were also found with PI of SGA preterm infants, as those infants classified by Olsen were mostly symmetric (PI > 10th percentile), while Fenton and Intergrowth-21st identified less symmetric SGA infants. Kappa concordance between Intergrowth-21st and Fenton was 0.805, Intergrowth-21st versus Olsen 0.824, and Fenton versus Olsen 0.641. No differences were observed on neonatal morbidities or mortality.

CONCLUSION

 Significant differences were detected when classifying very preterm infants at birth according to the growth chart, mainly among symmetric SGA. Concordance between Fenton and Olsen was poor, but Intergrowth-21st showed high concordance with Fenton and Olsen. However, further research is needed to select the ideal chart. Variability in the population selected to create the curves and the accuracy dating the pregnancy are factors that may have explained differences.

KEY POINTS

· Very preterm infants are differently classified at birth with various growth charts.. · Higher incidence of small for gestational age infants with Olsen compared with Fenton or Intergrowth.. · Variability in population selection and accuracy in dating pregnancy may have explained differences..

Physiological responses and behavioural organization of very low birth weight infants during swaddled versus traditional weighing

AIM

Despite the consequences of neonatal distress and agitation, preterm infants undergo stress owing to weighing procedures. The objective of this study was to enable very low birth weight infants to maintain adequate self-regulation during weighing.

DESIGN

This prospective crossover study utilizes a within-subjects design, where intervention days were compared to control days.

METHOD

Infants were exposed to both swaddled and unswaddled weighing in an intensive care nursery setting. Nineteen very low birth weight infants were weighed on two consecutive days. Variables of heart rate, respiratory rate and ALPS-Neo score were recorded.

RESULTS

Stress score decreased significantly from 1.65 (pre-weight) to 0.23 (weight measurement) in swaddled-intervention periods; conversely, it increased significantly from 1.26 (pre-weight) to 4.97 (weight measurement) in control periods. During weight measurement, heart and respiratory rate were significantly lower for swaddled-intervention days when compared to control days. Given the significant impact of swaddled weighing in reducing stress, this method can be used as an appropriate weighing procedure in intensive care. This research has no patient or public contribution.

The association of low body mass index with neonatal morbidities in preterm infants

Little is known about the association between body proportionality at birth and neonatal outcomes in preterm infants. Body mass index (BMI) is one of the weigh-for-length ratios that represent body proportionality. The objective of this study was to examine whether BMI at birth affects neonatal outcomes in preterm infants. We assessed 3115 preterm (< 30 weeks), very low birth weight (< 1500 g) infants born between January 2013 and December 2016 and registered in the Korean Neonatal Network database. Using gender-specific BMI for gestational age curves, z-scores of BMI at birth were calculated. Low-, normal-, and high-BMI were defined as BMI z-scores of less than - 1, from - 1 to 1, and greater than 1, respectively. Neonatal morbidities and mortality in low- and high-BMI groups were compared to those in normal-BMI group. The low-BMI group had an increased risk of bronchopulmonary dysplasia, bronchopulmonary dysplasia or death, and necrotizing enterocolitis after adjusting for baseline characteristics and the birth weight z-score. High-BMI group had comparable neonatal outcomes to those of normal-BMI group. Low BMI at birth was associated with an increased risk of bronchopulmonary dysplasia and necrotizing enterocolitis, whereas High BMI at birth was not associated with adverse neonatal outcomes.

Impact of being large-for-gestational-age on neonatal mortality and morbidities in extremely premature infants

BACKGROUND

Small for gestational age (SGA) infants have an increased risk for neonatal mortality and morbidities. However, few studies have examined the risk of large for gestational age (LGA) on these factors. We compared the risk of mortality and morbidities in LGA premature infants with those of appropriate for gestational age (AGA) infants.

METHODS

Premature infants who were born between 2003 and 2012 at <26 weeks of gestational age were included. Relative risks of mortality and morbidities were evaluated between LGA and AGA infants.

RESULTS

From 6898 extremely premature infants, 357 (5.2%), 5530 (80.2%), and 1011 (14.7%) were LGA, AGA, and SGA, respectively. A total of 5887 infants (5530 AGA and 357 LGA) were examined after excluding infants with congenital anomalies, unknown sex, and deficient data. The risk of mortality in LGA and AGA infants did not differ (relative risk (95% confidence interval) 1.04 (0.83-1.32)). Compared to AGA infants, LGA infants did not increase the risk of morbidities, including intraventricular hemorrhage, cystic periventricular leukomalacia, treated retinopathy of prematurity, necrotizing enterocolitis, and bronchopulmonary dysplasia.

CONCLUSIONS

This study demonstrates that being born LGA does not correlate with an increased risk of mortality and morbidities in extremely premature infants.

IMPACT

It is currently unknown if being large for gestational age is a risk for neonatal morbidity. A total of 6898 preterm infants born <26 weeks gestational age were included in the study. It was found that being large for gestational age was not related to increased risk of mortality and morbidities.

Quantile contours and allometric modelling for risk classification of abnormal ratios with an application to asymmetric growth-restriction in preterm infants

We develop an approach to risk classification based on quantile contours and allometric modelling of multivariate anthropometric measurements. We propose the definition of allometric direction tangent to the directional quantile envelope, which divides ratios of measurements into half-spaces. This in turn provides an operational definition of directional quantile that can be used as cutoff for risk assessment. We show the application of the proposed approach using a large dataset from the Vermont Oxford Network containing observations of birthweight (BW) and head circumference (HC) for more than 150,000 preterm infants. Our analysis suggests that disproportionately growth-restricted infants with a larger HC-to-BW ratio are at increased mortality risk as compared to proportionately growth-restricted infants. The role of maternal hypertension is also investigated.

Updates on Assessment and Monitoring of the Postnatal Growth of Preterm Infants

Assessing and monitoring the physical growth of preterm infants is fundamental to NICU care. The goals of nutritional care are to approximate the growth and body composition of the healthy fetus and to support optimal brain development while minimizing future cardiometabolic risk. Both poor and excessive growth predict adverse long-term health outcomes. Growth curves are clinical tools used to assess the preterm infant's growth status. Several growth curves for preterm infants were developed in the past decade. To use them effectively, clinicians need to understand how each growth curve was developed; the underlying reference population; intended use; and strengths and limitations. Intrauterine growth curves are references that use size at birth to represent healthy fetal growth. These curves serve 2 purposes-to assign size classifications at birth and to monitor postnatal growth. The INTERGROWTH-21 ^st preterm postnatal growth standards were developed to compare the postnatal growth of preterm infants to that of healthy preterm infants rather than the fetus. Individualized weight growth curves account for the water weight loss that frequently occurs after birth. In addition, body mass index (BMI) curves are now available. In this review, we discuss the main characteristics of growth curves used for preterm infants as well as the use of percentiles, z scores, and their change over time to evaluate size and growth status. We also review the differences in body composition between preterm infants at term-equivalent age and term-born infants and the potential role of monitoring proportionality of growth using BMI curves.

Cohort study showed that growth rate increment has not been enough to prevent growth retardation of preterm infants and raised concerns about unbalanced growth

AIM

We describe the postnatal weight gain, linear and head growth trends of surviving preterm infants from 2005 to 2017.

METHODS

Multicentre cohort study, including surviving preterm infants <32 weeks (n = 21 084), from the Spanish Neonatal Network database, without major congenital malformations who were less than 50 weeks postmenstrual age at discharge. Outcomes were weight gain (g/kg/day), linear and head growth (cm/week) and changes in weight, length and head circumference z-scores from birth to discharge. The study period was divided into 2005-8, 2009-11, 2012-14 and 2015-17.

RESULTS

Weight gain, linear growth and head growth were slightly higher in 2015-2017 than in 2005-2008: 12.2 ± 2.6 to 13.1 ± 2.5 g/kg/day, 0.98 ± 0.6 to 1.03 ± 0.6 cm/week and 0.76 ± 0.2 to 0.77 ± 0.3 cm/week, respectively. It was associated with a decreased fall in weigh, length and head circumference z-scores from birth to discharge (-1.32 ± 0.9 to -1.01 ± 0.84, -1.38 ± 1.2 to -1.18 ± 1.2 and -0.41 ± 1.2 to -0.33 ± 1.3, respectively).

CONCLUSION

Postnatal growth restriction remained a common complication of prematurity despite some increment over the last years. Growth disproportionality seemed to be worsening as weight gain was increased more than linear growth.

Nutritional Assessment in Preterm Infants: A Practical Approach in the NICU

A practical approach for nutritional assessment in preterm infants under intensive care, based on anthropometric measurements and commonly used biochemical markers, is suggested. The choice of anthropometric charts depends on the purpose: Fenton 2013 charts to assess intrauterine growth, an online growth calculator to monitor intra-hospital weight gain, and Intergrowth-21st standards to monitor growth after discharge. Body weight, though largely used, does not inform on body compartment sizes. Mid-upper arm circumference estimates body adiposity and is easy to measure. Body length reflects skeletal growth and fat-free mass, provided it is accurately measured. Head circumference indicates brain growth. Skinfolds estimate reasonably body fat. Weight-to-length ratio, body mass index, and ponderal index can assess body proportionality at birth. These and other derived indices, such as the mid-upper arm circumference to head circumference ratio, could be proxies of body composition but need validation. Low blood urea nitrogen may indicate insufficient protein intake. Prealbumin and retinol binding protein are good markers of current protein status, but they may be affected by non-nutritional factors. The combination of a high serum alkaline phosphatase level and a low serum phosphate level is the best biochemical marker for the early detection of metabolic bone disease.

Enhanced Protein Diet for Preterm Infants: A Prospective, Randomized, Double-blind, Controlled Trial

OBJECTIVE

To evaluate dietary protein's effect on fat accretion and weight gain in hospitalized preterm infants.

METHODS

Prospective, randomized, double-blind, controlled trial of 36 infants born at <32 weeks, hospitalized in a tertiary neonatal intensive care unit. After achieving full enteral volume, infants were randomized to either an enhanced protein diet (EPD) (protein-energy ratio [PER] 4 g/100 calories) or a standard protein diet (SPD) (PER 3 g/100 calories). Macronutrients were calculated using published values for formula, donor milk bank analysis, or weekly analysis of a 24-hour pooled maternal milk sample. Human milk fortifier and/or liquid protein were used to achieve the target PER until discharge or a maximum of 4 weeks. Body composition was measured weekly using air displacement plethysmography. The principal outcomes, rates of weight gain and fat accretion, were compared between groups in linear mixed models.

RESULTS

Thirty-three infants received approximately 17 days of the study diet. Relative weight gain was 21.6 g · kg · day (95% confidence interval [CI] 19.5-23.8) for the EPD group (n = 16) versus 19.1 g · kg · day (95% CI 17.0-21.2) for the SPD group (n = 17), P = 0.095. Baseline percent fat mass (FM) in the EPD group was 5.15% (95% CI 3.58%-6.72%) compared with 7.29% (95% CI 5.73%-8.84%) in the SPD group, P = 0.0517. Percent FM increased 0.398%/day (95% CI 0.308-0.488) for the EPD group versus 0.284%/day (95% CI 0.190-0.379) for the SPD group (P = 0.0878).

CONCLUSIONS

Preterm infants with a lower baseline FM percentage who received an EPD demonstrated a more pronounced catch-up percentage of fat accretion.

Effects of Massage Therapy and Kinesitherapy to Develop Hospitalized Preterm Infant's Anthropometry: A Quasi-Experimental Study

PURPOSE

The aim of this study was to analyze the efficacy of massage therapy and kinesitherapy on the anthropometric development of hospitalized preterm infants applied by parents.

DESIGN AND METHODS

A prospective quasi-experimental study was designed. Hospitalized preterm infants received a daily 15-minute session of massage therapy and kinesitherapy. The control group received regular medical and nursing care.

RESULTS

The massage therapy and kinesitherapy protocol significantly improved the anthropometric parameters studied: weight (895.7 ± 547.9 vs 541.8 ± 536.2; p < 0.001) size (5.5 ± 4.3 vs. 3.0 ± 3.1; p < 0.001) and head circumference (4.2 ± 3.2 vs 2.4 ± 2.6; p < 0.001).

CONCLUSIONS

The implementation of a massage therapy and kinesitherapy protocol is beneficial for the anthropometric development of hospitalized preterm infants.

PRACTICE IMPLICATIONS

An easy to administer and cost-effective intervention such as massage therapy and kinesitherapy can improve the anthropometric development of preterm infants and reduce growth-related morbidity in the short, medium, and long term.

Association of prenatal exposure to organochlorine pesticides and birth size

There has been substantial evidence showing the adverse effects of organochlorine pesticide (OCP) exposure on human, but studies focused on the prenatal exposure effects at low OCP levels on infant birth size were scarce and controversial. In this study, cord serum samples were collected at the delivery from 1028 pairs of mothers and newborns in Wuhan, China and investigated the associations of prenatal exposure to OCPs and birth size. The prenatal exposure of hexachlorocyclohexane isomers (HCHs), p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) and its metabolites were analyzed. The associations between birth size and prenatal OCP exposure were examined by multiple linear regressions. A sex-specific relationship between the OCP exposure and birth size was observed. β-HCH was negatively associated with birth weight and ponderal index for boys [adjusted β = -28.61; 95% confidence interval (CI): -54.84, -4.37 and adjusted β = -0.17; 95% CI: -0.32, -0.01, respectively], whilst no significant associations with prenatal exposure of OCPs were found among girls. The inverse association of prenatal exposure to low levels of β-HCH was shown sex-specific difference, which was only observed significantly in boys. The findings strengthened the evidence that the fetal development was influenced by prenatal exposure to certain OCPs and the effects might be different in the newborn sex.

Valid serial length measurements in preterm infants permit characterization of growth patterns

BACKGROUND

The lack of a valid and safe method for measuring length in critically ill preterm neonates has led to a primary focus on weight gain.

LOCAL PROBLEM

Paucity of valid length measurements, precluding the accurate analysis of growth patterns.

METHODS

Quality improvement project among infants < 29 weeks or small for gestational age < 35 weeks with embedded validation of (1) a caliper (infantometer) for length measurements and (2) length measurements during the first week to estimate birth length.

INTERVENTION

Implementation of valid methods to measure length.

RESULTS

We validated infantometer measurements and first week length measurements. The percentage of neonates with valid measurements during the first week rose from 10% to 78%, resulting in increased identification of classifiable growth patterns from < 10% to 89%.

CONCLUSIONS

By increasing the percentage of neonates with valid length measurements in the first week postnatal, we identified an increased number of neonates with classifiable growth abnormalities.

Relationship between maternal phthalate exposure and offspring size at birth

Research findings on effects of prenatal phthalate exposure on fetal growth were inconsistent. Increasing evidence from animal studies has indicated a potential sex-specific effect of phthalates on fetal growth, but the current human data was limited. In this study, we aimed to estimate the relationships between maternal phthalate exposure and infant birth size. Six major phthalate metabolite levels of urine samples were measured among pregnant women (n=1002) from the Healthy Baby Cohort (HBC), China. The associations between urinary phthalate metabolites levels and birth size (birth weight, birth length, birth weight z-scores and ponderal index) were estimated using linear regression models. In boys, the ln-transformed di-2-ethylhexyl phthalate (DEHP) metabolite levels were significantly associated with increased birth weight and birth weight z-scores. Additionally, each ln-unit increase in mono-(2-ethyl-5-carbox-ypentyl) phthalate (MECPP) was associated with a 0.25kg/m³ [95% confidence interval (CI): 0.03, 0.47] increase in ponderal index in boys. However, we did not observe any significant association of maternal phthalate metabolite levels with any of the outcomes in girls. Our data suggested potential sex-specific associations of maternal phthalate exposure with increased birth weight and ponderal index, which were merely apparent in boys.

The clinical utility of anthropometric measures to assess adiposity in a cohort of prematurely born infants: Correlations with MRI fat quantification

OBJECTIVE

To correlate magnetic resonance imaging (MRI) of body fat in preterm infants at the time of hospital discharge with same-day anthropometric measures, and to assess the clinical utility of body mass index (BMI), waist circumference (WC), and WC/length ratio as indicators of visceral fat.

STUDY DESIGN

MRI performed prior to NICU discharge in 25 infants born preterm at <32 weeks gestation. Total body fat and visceral fat were quantified using a commercial software program. The Pearson correlation coefficient (r, 95% C.I.) was used to describe strength of association between MRI fat and anthropometric measures.

RESULTS

BMI and weight at discharge were strongly correlated with total body fat (r = 0.95 and 0.89 respectively; p < 0.001). Total body fat as a % of body weight was moderately correlated with weight (r = 0.53), WC (r = 0.52), and BMI (r = 0.47). Weight, BMI, and ponderal index all were found to correlate with total visceral fat (r = 0.65, 0.64, 0.55 respectively) but WC did not (r = 0.28). WC/length ratio was not correlated with any MRI fat measurements.

CONCLUSIONS

BMI and weight at discharge both correlate with MRI fat measurements. Our findings do not support the usefulness of measuring WC or WC/length ratio in preterm infants at term-equivalent age.

Weight gain and hypertension at three years of age and older in extremely low birth weight infants

OBJECTIVE

To determine the prevalence and weight gain as a risk factor of hypertension (HTN) at three years of age and older among extremely low birth weight (ELBW) infants.

STUDY DESIGN

Retrospective cohort study of all ELBW infants born and followed up at our institution over 15 years.

RESULTS

204 infants were followed up for [median (inter-quartile range)] 10.2 years (6.9-13.0). Their birth weight and gestational age were (mean±standard deviation) 758±149 g and 26.4±2.1 weeks respectively. At 3 years of age and older, the prevalence of HTN was 7.3% (15/204), and the prevalence of obesity was 13.2% (27/204). Obesity was more prevalent in children with than without HTN [33% (5/15) vs. 12% (22/189); p = 0.01]. In a regression analysis, body mass index (BMI) percentile at 3 years of age and older (p = 0.04) and increase in weight Z scores since birth (p = 0.008) were associated with a higher systolic blood pressure (SBP; R = 0.386, p <  0.001).

CONCLUSION

Obesity is prevalent in ELBW infants at three years of age and older, and it is significantly associated with hypertension. An increase in BMI percentile at ≥3 years of age, and the rate of weight gain since birth among ELBW infants are associated with an increase in SBP.

Preterm infant body composition cannot be accurately determined by weight and length

BACKGROUND

Body composition is a key metric for assessing nutrition in preterm infants. In many neonatal intensive care units body composition is estimated using anthropometric indices which mathematically combine body weight and length. However, the accuracy of these indices is unknown in preterm infants. In contrast, air-displacement plethysmography (ADP) has been shown to accurately measure neonatal fat mass, but it is not widely available.

OBJECTIVE

The aim was to determine which anthropometric index is most correlated to infant fat mass, as determined by ADP.

DESIGN

We performed a retrospective observational study, comparing ADP-determined percent body fat at 366 time points for 239 preterm infants (born <32 weeks), with simultaneous weight and length measurements. Non-linear regression was performed to determine the best fit anthropometric index to the body fat percentage as determined by ADP. Our non-linear regression model, % fat = AxwtαxLβ, is the generalization of the most common anthropometric indices (BMI, ponderal index, etc.).

RESULTS

The best-fit regression formula most closely matched the formula for BMI. However, the regression explained only 51% of variability seen in body fat percentage at post-menstrual age <50 weeks, and 16% of variation seen at 50 weeks or greater.

CONCLUSION

Even optimal formulas relating weight and length to body fat percentage predict only a fraction of the variation seen in body composition, especially beyond 50 weeks. BMI was the anthropometric index most predictive of body fat percentage, but still has limited accuracy.

Maternal obesity, diabetes mellitus and cord blood biomarkers in large-for-gestational age infants

Infants born large-for-gestational age (LGA) are at risk for early childhood obesity. The aims of this study were to investigate factors associated with LGA status and their relationship to inflammatory biomarkers that have been implicated in the LGA infant at birth. Included were 364 mother-infant pairs enrolled as part of an ongoing longitudinal cohort study of infant birth weight being conducted at Boston Medical Center (BMC). LGA was defined as birth weight (BW) ≥90(th) percentile of the reference population at BMC (N=45). Appropriate-for-gestational age (AGA) was defined as BW<90(th) and >10(th) percentile (N=319). Cord blood IL-6, IL-8, TNF-alpha and RANTES levels were analyzed from a larger panel of immune biomarkers measured using multiplex immunoassay. Multivariate regression models were used to determine the associations between LGA status, maternal BMI and diabetes (DM), which included either gestational or type 2 diabetes (T2DM), and cord blood biomarkers, with adjustment for important demographic and clinical variables. Maternal pre-pregnancy BMI within the obesity range (≥30 kg/m(2)), as well as DM, were each associated with increased risk of LGA (OR=2.64, 95%CI 1.31-6.20; OR=5.58, 95%CI 2.06-15.13, respectively). Among the 4 biomarkers, only RANTES (regulated on activation, normal T cell express and secreted upon uptake), which is a chemokine secreted by white adipose tissue, was significantly increased in LGA infants (beta-coefficient=0.37; 95% CI: 0.09, 0.65; P<0.01). This association remained essentially unchanged after adjustment for maternal DM and BMI (beta-coefficient=0.37; 95% CI: 0.08, 0.65; P=0.01). Ponderal index (PI=BW×100/length(3)) was also positively correlated with RANTES. Cord blood RANTES is selectively elevated with fetal macrosomia, independent of maternal factors. Further investigation of RANTES as a marker of LGA and future childhood health is warranted.

Length Normalized Indices for Fat Mass and Fat-Free Mass in Preterm and Term Infants during the First Six Months of Life

Objective: Postnatal tissue accretion in preterm infants differs from those in utero, affecting body composition (BC) and lifelong morbidity. Length normalized BC data allows infants with different body lengths to be compared and followed longitudinally. This study aims to analyze BC of preterm and term infants during the first six months of life. Methods: The BC data, measured using dual energy X-ray absorptiometry, of 389 preterm and 132 term infants from four longitudinal studies were combined. Fat-mass/length² (FMI) and fat-free mass/length² (FFMI) for postmenstrual age were calculated after reaching full enteral feeding, at term and two further time points up to six months corrected age. Results: Median FMI (preterm) increased from 0.4 kg/m² at 30 weeks to 2.5, 4.3, and 4.8 kg/m² compared to 1.7, 4.7, and 6 kg/m² in term infants at 40, 52, and 64 weeks, respectively. Median FFMI (preterm) increased from 8.5 kg/m² (30 weeks) to 11.4 kg/m² (45 weeks) and remained constant thereafter, whereas term FFMI remained constant at 11 kg/m² throughout the tested time points. Conclusion: The study provides a large dataset of length normalized BC indices. Followed longitudinally, term and preterm infants differ considerably during early infancy in the pattern of change in FMI and FFMI for age.

Infants born large-for-gestational-age display slower growth in early infancy, but no epigenetic changes at birth

We evaluated the growth patterns of infants born large-for-gestational-age (LGA) from birth to age 1 year compared to those born appropriate-for-gestational-age (AGA). In addition, we investigated possible epigenetic changes associated with being born LGA. Seventy-one newborns were classified by birth weight as AGA (10(th)-90(th) percentile; n = 42) or LGA (>90(th) percentile; n = 29). Post-natal follow-up until age 1 year was performed with clinical assessments at 3, 6, and 12 months. Genome-wide DNA methylation was analysed on umbilical tissue in 19 AGA and 27 LGA infants. At birth, LGA infants had greater weight (p < 0.0001), length (p < 0.0001), ponderal index (p = 0.020), as well as greater head (p < 0.0001), chest (p = 0.044), and abdominal (p = 0.007) circumferences than AGA newborns. LGA infants were still larger at the age of 3 months, but by age 6 months there were no more differences between groups, due to higher length and weight increments in AGA infants between 0 and 6 months (p < 0.0001 and p = 0.002, respectively). Genome-wide analysis showed no epigenetic differences between LGA and AGA infants. Overall, LGA infants had slower growth in early infancy, being anthropometrically similar to AGA infants by 6 months of age. In addition, differences between AGA and LGA newborns were not associated with epigenetic changes.

Nutritional support for premature infants in the neonatal intensive care unit

Nutritional support for premature infants in the neonatal intensive care unit setting is complex. Such infants have conditions unique to this period of the lifespan requiring specialized care management, both of which may impede the provision of adequate nutrition to support basal metabolic needs. Premature infants require optimum nutritional intake to support rapid growth during a time when they are not fully capable of tolerating it. This article reviews developmental anatomy, physiology, and the effect of premature delivery by systems; the challenges of providing adequate nutrition; and current evidence-based strategies to provide nutrition for premature infants during hospitalization.

BMI curves for preterm infants

BACKGROUND AND OBJECTIVES

Preterm infants experience disproportionate growth failure postnatally and may be large weight for length despite being small weight for age by hospital discharge. The objective of this study was to create and validate intrauterine weight-for-length growth curves using the contemporary, large, racially diverse US birth parameters sample used to create the Olsen weight-, length-, and head-circumference-for-age curves.

METHODS

Data from 391 681 US infants (Pediatrix Medical Group) born at 22 to 42 weeks' gestational age (born in 1998-2006) included birth weight, length, and head circumference, estimated gestational age, and gender. Separate subsamples were used to create and validate curves. Established methods were used to determine the weight-for-length ratio that was most highly correlated with weight and uncorrelated with length. Final smoothed percentile curves (3rd to 97th) were created by the Lambda Mu Sigma (LMS) method. The validation sample was used to confirm results.

RESULTS

The final sample included 254 454 singleton infants (57.2% male) who survived to discharge. BMI was the best overall weight-for-length ratio for both genders and a majority of gestational ages. Gender-specific BMI-for-age curves were created (n = 127 446) and successfully validated (n = 126 988). Mean z scores for the validation sample were ∼0 (∼1 SD).

CONCLUSIONS

BMI was different across gender and gestational age. We provide a set of validated reference curves (gender-specific) to track changes in BMI for prematurely born infants cared for in the NICU for use with weight-, length-, and head-circumference-for-age intrauterine growth curves.

The role of nutrition in promoting growth in pre-term infants with bronchopulmonary dysplasia: a prospective non-randomised interventional cohort study

Background

Pre-term infants who develop bronchopulmonary dysplasia (BPD) are at risk of postnatal growth failure. It has been reported that energy expenditure is higher in infants with BPD than in those without BPD. The aim of the study was to evaluate whether increasing the enteral energy intake of pre-term infants with BPD can improve post-natal growth.

Methods

This prospective, non-randomised interventional cohort study was designed to assess growth in 57 preterm infants with BPD (gestational age <32 weeks, birth weight <1500 g, and persistent oxygen dependency for up to 28 days of life) fed individually tailored fortified breast milk and/or preterm formula, and a historical control group of 73 pre-term infants with BPD fed breast milk fortified in accordance with the instructions of the manufacturer and/or pre-term formula. Between-group differences in the continuous variables were analysed using Student’s t test or the Mann-Whitney test; the discrete variables were compared using the chi-squared test. Linear regression analysis was used to investigate the independent contribution of enteral energy intake to weight gain velocity.

Results

The duration of parenteral nutrition was similar in the historical and intervention groups (43.7 ± 30.9 vs 39.6 ± 17.4 days). After the withdrawal of parenteral nutrition, enteral energy intake was higher in the infants in the intervention group with mild or moderate BPD (131 ± 6.3 vs 111 ± 4.6 kcal/kg/day; p < 0.0001) and in those with severe BPD (126 ± 5.3 vs 105 ± 5.1 kcal/kg/day; p < 0.0001), whereas enteral protein intake was similar (3.2 ± 0.27 vs 3.1 ± 0.23 g/kg/day).

Weight gain velocity was greater in the infants in the intervention group with mild or moderate BPD (14.7 ± 1.38 vs 11.5 ± 2 g/kg/day, p < 0.0001) and in those with severe BPD (11.9 ± 2.9 vs 8.9 ± 2.3 g/kg/day; p < 0.007). The percentage of infants with post-natal growth retardation at 36 weeks of gestational age was higher in the historical group (75.3 vs 47.4; p = 0.02).

Conclusions

On the basis of the above findings, it seems that improved nutritional management promotes post-natal ponderal growth in pre-term infants with BPD.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2431-14-235) contains supplementary material, which is available to authorized users.

Assessment of neonatal growth in prematurely born infants

The concept that adequate nutritional status and normal growth are important is well-accepted. How to assess the adequacy of nutrition and how to define appropriate growth remains an area of active debate. Our goal is to review how growth is assessed at birth and during the hospital stay of prematurely born infants, and to offer a standardized approach.

Respiratory syncytial virus disease in preterm infants in the U.S. born at 32-35 weeks gestation not receiving immunoprophylaxis

BACKGROUND

The Respiratory Syncytial Virus (RSV) Respiratory Events Among Preterm Infants Outcomes and Risk Tracking (REPORT) study evaluated RSV disease burden in U.S. preterm infants 32-35 weeks gestational age (wGA) not receiving RSV prophylaxis.

METHODS

Preterm infants <6 months of age as of November 1st were followed prospectively at 188 clinics from September to May 2009-2010 or 2010-2011. Nasal and pharyngeal swabs were collected for medically attended acute respiratory illnesses (MAARI) and tested for RSV by qRT-polymerase chain reaction. Risk factors were assessed using multivariate Cox proportional hazard model adjusted for seasonality.

RESULTS

Of 1642 evaluable infants, 287 experienced RSV MAARI. Rates of RSV-related MAARI, outpatient lower respiratory tract illness, emergency department visits and hospitalization (RSVH) during November to March were 25.4, 13.7, 5.9 and 4.9 per 100 infant-seasons, respectively. Preschool-aged, nonmultiple-birth siblings and daycare attendance were consistently associated with increased risk of RSV. RSVH rates were highest in infants 32-34 and 35 wGA who were <6 months of age during November to March with daycare attendance or nonmultiple-birth, preschool-aged siblings (8.9 and 9.3 per 100 infant-seasons, respectively, versus 3.5 for all other infants, P<0.001). Chronologic age <3 months was associated with a higher RSVH rate for infants 35 wGA but not for infants 32-34 wGA.

CONCLUSIONS

In US preterm infants who were 32-35 wGA, <6 months on November 1st and not receiving RSV prophylaxis, the burden of RSV MAARI was 25 per 100 infant-seasons. The highest RSVH rates occurred among those with daycare attendance or nonmultiple-birth, preschool-aged siblings while they were <6 months of age during the RSV season.

Can body mass index accurately predict adiposity in newborns?

Body mass index (BMI) is correlated with body fatness and risk of related diseases in children and adults. Proportionality indexes such as BMI and ponderal index (PI) have been suggested as complementary measures in neonatal growth assessment. Yet, they are still not used in neonates and their correlation with fatness is unknown. The aim of the study was to test the hypothesis that BMI z-score would predict neonatal adiposity. Body composition measurements (ie, fat mass, fat-free mass) by air displacement plethysmography (PEA POD, LMI, Concord-USA), weight and length were obtained in 200 infants ≥36 weeks' gestational age (GA) at birth. Linear regression analysis showed a direct association between BMI z-score and %fat mass (r(2)=0.43, p<0.0001). This association was confirmed independently from sex, GA and maternal prepregnancy BMI. BMI z-score predicted adiposity better than PI. However, both BMI z-score and PI were poor predictors of adiposity at birth.

The Association between Weight for Gestational Age and Kidney Volume: A Study in Newborns in India

OBJECTIVE

The association of low birth weight (LBW) with adult onset diseases like hypertension is suggested to be partially mediated by a low number of nephrons at birth. Studies have established a relation between LBW and renal volume as the latter is a surrogate marker of total nephron number. Most such studies have considered birth weight or gestational age as separate independent predictors, without taking into consideration the baby's weight with respect to its gestational age. This study aims to investigate the influence of weight for gestational age on kidney volume in newborns.

METHODS

Consecutive newborns delivered in the department of neonatology in a tertiary care medical college and hospital, were included in a cross-sectional study. The subjects were classified as appropriate for gestational age (AGA) and small for gestational age (SGA) as per Lubchenco's charts of weight for gestational age (WGA). Bilateral kidney dimensions were measured by a single observer and combined kidney volumes were calculated and compared between the groups. Findings : Four hundred and seventeen newborns (SGA 159; AGA 258) were included. The mean combined kidney volume (CKV) was significantly lower among SGA newborns (13.85±4.02 cm(3)) compared to that of AGA (16.88±4.53 cm(3)) (P<.001). Univariable and multivariable analyses were done for assessing the effect of demographic, anthropometric and maternal parameters on CKV. WGA, crown heel length, gestational age and postnatal age (hours of life) were independent predictors of mean CKV. An SGA newborn was expected to have a mean CKV 1.57 cm less (95% CI -2.49 cm to -0.65 cm) than that of its AGA counterpart.

CONCLUSION

Considering the future implications of being SGA and having low kidney volumes at birth, it is essential to have an objective depiction of the relationship between these two vital parameters. This study from the Indian subcontinent brings forth such an association.

Is intrauterine growth appropriate to monitor postnatal growth of preterm neonates?

When using the useful 2013 Fenton Chart, data should be interpreted with caution taking into account two aspects: the physiologic loss of body water after birth for the weight curves, and the questionable accuracy of the birth length curves considering the heterogeneity and reliability of the methods used in the original measurements.

Changes in plasma adipokines in prepubertal children with a history of extrauterine growth restriction

OBJECTIVE

Because nutritional support in perinatal life has been associated with metabolic programming, children with a history of extrauterine growth restriction (EUGR) might display alterations in the adipocyte and in the secretion of adipokines. The aim of this study was to assess adiponectin, resistin, and leptin concentrations in prepubertal children with a history of EUGR, and to determine the potential correlation between these adipokines and metabolic parameters.

METHODS

This case-control study sample included 38 prepubertal children with a history of EUGR and a control group of 123 healthy children of similar age and sex. Anthropometric measures and blood pressure were assessed. Biochemical markers and blood adipokine concentrations (adiponectin, resistin, and leptin) were evaluated.

RESULTS

Adiponectin concentration was significantly lower in the EUGR group compared with controls (EUGR: 11.49 ± 6.07 versus control: 25.72 ± 10.13 μg/mL), and resistin concentration was higher (EUGR: 20332.95 ± 6401.25 versus control: 8056.31 ± 3823.63 pg/mL), even after adjustment for gestational age, weight, and size at birth. Systolic blood pressure was associated with adipokines concentrations in the EUGR group (P < 0.001). In EUGR children adiponectin was associated with high-density lipoprotein cholesterol (P = 0.042), whereas resistin was associated with carbohydrate metabolism parameters (P < 0.001).

CONCLUSIONS

Early postnatal malnutrition in EUGR children could program adipose tissue. Plasma adipokines can be measured in childhood to identify precocious changes that may be associated with a higher risk for metabolic syndrome or cardiovascular disease later in life.

Novel noninvasive anthropometric measure in preterm and full-term infants: normative values for waist circumference:length ratio at birth

BACKGROUND

Waist circumference:length ratio (WLR) and ponderal index (PI) appear to be useful markers of visceral and total adiposity, respectively. However, there are no normative birth data across the full range of gestational ages.

METHODS

In this retrospective cohort study of 500 preterm and 1,426 full-term infants, born in 1998 and 2008 at three military hospitals, the percentile growth curves for WLR and PI were calculated. There were no sex differences, and results were combined to obtain values from 26 to 42 wk gestation.

RESULTS

Between 26 and 42 wk gestation, median birth WLR increased from 0.55 to 0.62, and median PI increased from 21.1 to 25.6. The adjusted mean WLR at birth among infants born <34 wk increased from 0.55 in 1998 to 0.58 in 2008 (P = 0.048), suggesting that early-preterm infants born in 2008 had greater abdominal adiposity than those born in 1998.

CONCLUSION

We report normative birth data for WLR and PI in preterm and full-term infants by gestational age and sex. WLR and PI may be useful as clinical markers of visceral and overall adiposity. In conjunction with other anthropometric measures, WLR and PI may be useful to monitor postnatal nutrition and growth and assess risk for later obesity and cardiometabolic disorders.

Nutritional assessment in neonatal and prepubertal children with a history of extrauterine growth restriction

BACKGROUND

Nutritional deficit during perinatal stage may induce significant alterations in adipose tissue and increase the risk of obesity, metabolic syndrome and cardiovascular disease in children with a history of extrauterine growth restriction (EUGR).

AIMS

To describe the nutritional status in neonatal and prepubertal with a history of EUGR and establish an association between EUGR and later conditions.

STUDY DESIGN

Descriptive, analytical, observational case-control study.

SUBJECTS

The study included a sample of 38 prepubertal children with a history of EUGR, and 123 gender-and-age matched controls.

OUTCOME MEASURES

The EUGR group was asked to answer a food frequency questionnaire. Analysis of body composition in both groups included anthropometric measurements, assessment of blood pressure and biochemical markers.

RESULTS

Newborns with EUGR received parenteral feeding with a standard nutritional regime and long-chain fatty acid support for 41 ± 23 days; enteral feeding with a special formula for premature infants was initiated at 7 ± 11 days of life. At the prepubertal stage, daily fiber and fatty acid intake in children who had experienced EUGR in the neonatal stage was below the recommended intake. In the EUGR group, the intake of vegetables, fruits and olive oil was below dietary recommendations, while the intake of butchery, fatty meats, pastries and snacks was above the recommendations for the Spanish population.

CONCLUSIONS

Appropriate nutrition education strategies should be developed for children with a history of EUGR to prevent later associated pathologies, as neonatal nutritional support and feeding during childhood are associated with an increase in diseases in this risk group.

Potential influence of total parenteral nutrition on body composition at discharge in preterm infants

OBJECTIVE

This study was undertaken to assess the potential influence of total parenteral nutrition (TPN) on body composition (BC) in preterm infants.

STUDY DESIGN

This prospective, observational study of infants born <35 weeks measured BC at discharge using air displacement plethysmography. The % body fat (BF) at discharge was correlated with variables gestational age (GA), severity of illness, days on oxygen, time to regain birth weight and duration of TPN.

RESULT

The 61 patients enrolled had a %BF at discharge of 13.9%. GA and TPN days correlated with %BF for the entire group. Multiple regression analysis identified that the time to regain birth weight added to the effect of GA, but not TPN. Isolating the influence of TPN in a subgroup of similarly aged infants (30-35 weeks) did not reveal a difference in body composition at the time of discharge between infants who did or did not receive TPN.

CONCLUSION

These findings fail to demonstrate a clear influence of TPN on the increased accrual of BF in premature infants and implicate gestational modification in nutrient/caloric utilization as a principle regulator of body composition in premature newborns.

Nutritional recommendations for the late-preterm infant and the preterm infant after hospital discharge

Early nutritional support of preterm infants is critical to life-long health and well being. Numerous studies have demonstrated that preterm infants are at increased risk of mortality and morbidity, including disturbances in brain development. To date, much attention has focused on enhancing the nutritional support of very low and extremely low birth weight infants to improve survival and quality of life. In most countries, preterm infants are sent home before their expected date of term birth for economic or other reasons. It is debatable whether these newborns require special nutritional regimens or discharge formulas. Furthermore, guidelines that specify how to feed very preterm infants after hospital discharge are scarce and conflicting. On the other hand, the late-preterm infant presents a challenge to health care providers immediately after birth when decisions must be made about how and where to care for these newborns. Considering these infants as well babies may place them at a disadvantage. Late-preterm infants have unique and often-unrecognized medical vulnerabilities and nutritional needs that predispose them to greater rates of morbidity and hospital readmissions. Poor or inadequate feeding during hospitalization may be one of the main reasons why late-preterm infants have difficulty gaining weight right after birth. Providing optimal nutritional support to late premature infants may improve survival and quality of life as it does for very preterm infants. In this work, we present a review of the literature and provide separate recommendations for the care and feeding of late-preterm infants and very preterm infants after discharge. We identify gaps in current knowledge as well as priorities for future research.

A new liquid human milk fortifier and linear growth in preterm infants

OBJECTIVES

To evaluate the growth, tolerance, and safety of a new ultraconcentrated liquid human milk fortifier (LHMF) designed to provide optimal nutrients for preterm infants receiving human breast milk in a safe, nonpowder formulation.

METHODS

Preterm infants with a body weight ≤ 1250 g fed expressed and/or donor breast milk were randomized to receive a control powder human milk fortifier (HMF) or a new LHMF for 28 days. When added to breast milk, the LHMF provided ∼20% more protein than the control HMF. Weight, length, head circumference, and serum prealbumin, albumin, blood urea nitrogen, electrolytes, and blood gases were measured. The occurrence of sepsis, necrotizing enterocolitis, and serious adverse events were monitored.

RESULTS

This multicenter, third party-blinded, randomized controlled, prospective study enrolled 150 infants. Achieved weight and linear growth rate were significantly higher in the LHMF versus control groups (P = .04 and 0.03, respectively). Among infants who adhered closely to the protocol, the LHMF had a significantly higher achieved weight, length, head circumference, and linear growth rate than the control HMF (P = .004, P = .003, P = .04, and P = .01, respectively). There were no differences in measures of feeding tolerance or days to achieve full feeding volumes. Prealbumin, albumin, and blood urea nitrogen were higher in the LHMF group versus the control group (all P < .05). There was no difference in the incidence of confirmed sepsis or necrotizing enterocolitis.

CONCLUSIONS

Use of a new LHMF in preterm infants instead of powder HMF is safe. Benefits of LHMF include improvements in growth and avoidance of the use of powder products in the NICU.

Preterm infants of lower gestational age at birth have greater waist circumference-length ratio and ponderal index at term age than preterm infants of higher gestational ages

OBJECTIVE

To assess anthropometric changes from birth to hospital discharge in infants born preterm and compare with a reference birth cohort of infants born full-term.

STUDY DESIGN

Retrospective chart review was conducted of 501 preterm and 1423 full-term infants. We evaluated birth and hospital discharge weight, length, and waist circumference (WC). WC/length ratio (WLR), ponderal index, and body mass index (BMI) were calculated. Preterm infants were categorized into quartiles (Q1-4) based on birth weight (BW).

RESULTS

At birth mean length, WC, WLR, BMI, and ponderal index were all significantly less for preterm infants in the lowest BW quartile (Q1) than preterm infants in higher BW quartiles or full-term infants. Although their weight, length, and BMI remained significantly less at discharge, preterm infants in Q1 had a disproportionate increase in WLR and ponderal index such that at discharge their WLR and ponderal index were greater than infants in Q2-3 and comparable with infants in Q4 and full-term infants. Discharge WLR and ponderal index in Q1 were significantly higher with decreasing postmenstrual age at birth.

CONCLUSIONS

Preterm infants of a lower birth postmenstrual age have disproportionate increases in WLR and ponderal index that are suggestive of increased visceral and total adiposity.

The effect of ponderal index at birth on the relationships between common LEP and LEPR polymorphisms and adiposity in adolescents

This study examined the effect of ponderal index (PI) at birth on the relationships between eight common polymorphisms of the leptin (LEP) and leptin receptor (LEPR) genes and adiposity in adolescents. A total of 823 European adolescents (45.4% girls) aged 14.8 ± 1.4 years were genotyped for the LEP (rs2167270, rs12706832, rs10244329, rs2071045, and rs3828942) and LEPR (rs1137100, rs1137101, and rs8179183) polymorphisms. The PI was calculated from parental reports of birth weight and length. Fat mass index (FMI) was calculated. Analyses were adjusted for relevant confounders. An "adiposity-risk-allele score" based on genotypes at the three single-nucleotide polymorphisms (SNPs) associated with adolescents' FMI in adolescents within the lower tertile of PI was calculated. The LEP rs10244329 and rs3828942 polymorphisms were associated with higher FMI only in adolescents within the lower PI tertile (+0.55 kg/m(2) per minor T allele, P = 0.040, and +0.58 kg/m(2) per major G allele, P = 0.028, respectively). The LEPR rs8179183 polymorphism was significantly associated with higher FMI in adolescents within the lower PI tertile (+0.87 kg/m(2) per minor C allele, P = 0.006). After correction for multiple comparisons, only the association between the LEPR rs8179183 and FMI persisted. However, each additional risk allele conferred 0.53 kg/m(2) greater FMI in adolescents within the lower tertile of PI (P = 0.008). In conclusion, our results suggest that those adolescents born with lower PI could be more vulnerable to the influence of the LEP rs10244329 and rs3828942 polymorphisms and LEPR rs8179183 polymorphism on total adiposity content. Due to the relatively small sample size, these findings should be replicated in further larger population samples.

Body size at birth modifies the effect of fat mass and obesity associated (FTO) rs9939609 polymorphism on adiposity in adolescents: the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study

The present study was intended to examine whether ponderal index (PI) at birth modifies the effect of the fat mass and obesity associated (FTO) rs9939609 polymorphism on adiposity in European adolescents. A total of 628 adolescents aged 14·4 (se 1·3) years (56·8 % female) were recruited. PI was calculated from parental reports of birth weight and length (kg/m³), and the BMI (kg/m²), body fat percentage and fat mass index (FMI, kg/m²) were calculated. The rs9939609 polymorphism was genotyped and physical activity assessed by accelerometry. Sex, duration of pregnancy, pubertal status, centre and physical activity were used as confounders in all the analyses. The minor A allele of the FTO rs9939609 was significantly associated with higher BMI, body fat percentage and FMI (all P < 0·05) but not with PI. Significant interactions between PI and the rs9939609 polymorphism in terms of body fat percentage (P = 0·002) and FMI (P = 0·017) were detected. However, this polymorphism was only significantly associated with higher BMI, body fat percentage and FMI (all P < 0·05) in adolescents in the lower PI tertile. Indeed, both body fat percentage and FMI were higher in those adolescents in the lower PI tertile carrying the A allele of the FTO rs9939609 polymorphism than in those with the TT genotype (25·0 (se 0·8) v. 22·1 (se 1·0) %, adjusted P = 0·030 and 5·6 (se 0·3) v. 4·6 (se 0·4) kg/m2, P = 0·031, respectively). Our findings suggest that those adolescents born with lower PI could be more vulnerable to the influence of the A risk allele of the FTO polymorphism on total adiposity content.

Graphical Exploration of Dimensions of Preterm Infant Growth in Weight in Association With Biological, Nutritional, and Energy Expenditure Conditions

The small sample sizes of studies involving preterm infants limit the use of statistics for examination of multivariate conditions contributing to clinically important growth dimensions of weight: rate of weight gain, body composition (fat-free and fat mass), and weight relative to reference infants (z score). The authors used graphical analyses, including multivariate proportional matrix, parallel coordinates, and bivariate plots with regression lines and splines, to explore specific variables derived from a theoretical model of biological, nutritional intake, and energy expenditure conditions influencing growth dimensions. The sample included 28 infants in 4 birth-weight categories: extremely low (<1,000 g), very low/smaller (1,000—1,249 g), very low/larger (1,250—1,499 g), and low (1,500—1,750 g). The authors examined the rate of weight gain before and after nipple feeding initiation. Fat-free mass was estimated with total body water and fetal reference data, and fat mass with skinfold thicknesses. Despite infants achieving the expected rate of weight gain for a fetus of the same postconceptional age, by hospital discharge 13 infants showed growth restriction with weight <10th centile. Infants with respiratory distress syndrome history were highest in negative z-score change from regain of birth weight to discharge, despite higher ordering on protein intake and fat-free mass. Graphical analyses provided visual patterns of distributions and orderings of measures of multiple variables that, taken together, identified potential influencing conditions and raised questions for further study. Other variables, including feeding protocols and practices, infant feeding competence, and health status, may contribute to variability in weight growth dimensions and influence relationships with biologic, nutritional, and energy expenditure conditions.

Post-natal growth of 157 children born as extremely premature neonates

AIM

With increasing survival rate of extremely premature neonates, their long-term outcomes including growth and risk factors for later disorders need to be considered. We prospectively evaluated anthropometric parameters in children born as extremely premature neonates.

METHODS

Anthropometric parameters were measured at the ages of 2 and 5 years in 72 extremely premature children born between the 22nd and 25 + 6th weeks of gestation (group I) and 85 children born between the 26th and 27 + 6th weeks of gestation (group II).

RESULTS

Although catch-up in the postnatal growth was observed in both groups of children, resulting in growth improvement, the height of the extremely premature children at the ages of 2 and 5 years remains lower (P < 0.01) compared with the control population. A decline in head growth was observed in both groups between the ages of 2 and 5 years, resulting in decrease of standard deviation score (SDS) for head circumference (HC) in comparison with that of the control population, accompanied by an increased number of children with microcephaly, defined as HC < -2 SD. At the age of five, microcephaly was found in 18% of children from group I and 11.7% of children from group II. At the age of 5 years, the waist and hip circumferences and ten skinfolds were not different between both groups of children.

CONCLUSION

Long-term follow-up of extremely premature neonates is important not only to establish their growth patterns but also for risk factors assessment including adiposity for later development of adult-onset diseases.

Weight gain in infancy and early childhood is associated with school age body mass index but not intelligence and blood pressure in very low birth weight children

Rates of weight gain in infancy and early childhood can influence later neurocognitive, metabolic and cardiovascular health. We studied the relationship of weight gain during infancy and early childhood to intelligence quotient (IQ), blood pressure (BP) and body mass index (BMI) at age 9 in children born with very low birth weight (VLBW). Sixty-five children born prematurely with VLBW were followed longitudinally and at 9 years IQ, BP and BMI were measured. The mean weight z-scores at birth, neonatal intensive care discharge, 1 year corrected for prematurity, 5 and 9 years were -0.17, -2.09, -1.3, -0.68 and 0.06, respectively. Weight gain during infancy (discharge to 1 year corrected for prematurity) and early childhood (1 year corrected age to 5 years) was expressed as rate of change in weight, rate of change in weight z-score and interval change in weight z-score. In multiple regression analyses that adjusted for race, gender, maternal education, antenatal steroids, birth weight z-score, major intracranial lesions on ultrasound and chronic lung disease, rates of weight gain in infancy and early childhood were predictive of BMI z-score at 9 years, regression coefficients (95% confidence intervals); 0.19 (0.02, 0.36) and 0.37 (0.11, 0.63), respectively, expressed as change in BMI z-score per 10 g/week weight increase. Rates of weight gain were not predictive of systolic BP z-score, Verbal IQ or Performance IQ. In VLBW infants, more rapid weight gain during infancy, and especially early childhood, is associated with higher BMI at school age.

Induced preterm birth in sheep: a suitable model for studying the developmental effects of moderately preterm birth

Our aim was to characterize an ovine model of preterm birth that allows analysis of the developmental effects of preterm birth in the absence of postnatal confounding factors. Preterm birth was induced at 131 days of gestation in 82 lambs; controls (n = 31) were born at term (145 days). Overall survival of preterm lambs was 60%; males had significantly lower survival than females (44% vs 76%); 94% of term lambs survived. Although the birth weight of preterm lambs was approximately 0.9 kg lower than in term lambs, the crown-to-rump and forelimb lengths were similar. At 9 weeks after term-equivalent age, there were no differences in body weight or dimensions between preterm and term lambs; when adjusted for body weight, the heart was 21% heavier in preterm than term lambs. We conclude that moderately preterm birth in sheep is characterized by a greater survival of female lambs than males and has significant effects on organ development.

Birth weight percentile charts based on daily measurements for very preterm male and female infants at the age of 154-223 days

OBJECTIVE

Birth weight percentiles based on weekly measurements are used to assess the nutritional status of preterm infants. However, as preterm infants exhibit a rapid growth rate (up to 20 g/kg/day), their body weight can increase by 15% per week. We calculated birth weight percentiles based on daily measurements, to more precisely classify very preterm infants (gestational age of 154-223 days).

METHODS

Data of 23,864 (10,720 females and 13,144 males) very preterm singleton infants with a gestational age of 154-223 days (22-31 completed weeks) were retrieved from the German perinatal statistics of 1995-2000. Percentile curves based on the empirical birth weight data were subjected to three statistical smoothing procedures: cubic regression, local regression (LOESS smoothing), and the LMS method.

RESULTS

Smoothing of the birth weight percentiles using cubic regression produced the smallest residual variance.

CONCLUSION

Birth weight percentiles based on daily averages allow a more precise assessment of the somatic development of preterm infants.

New intrauterine growth curves based on United States data

OBJECTIVE

The objective of this study was to create and validate new intrauterine weight, length, and head circumference growth curves using a contemporary, large, racially diverse US sample and compare with the Lubchenco curves.

METHODS

Data on 391 681 infants (Pediatrix Medical Group) aged 22 to 42 weeks at birth from 248 hospitals within 33 US states (1998-2006) for birth weight, length, head circumference, estimated gestational age, gender, and race were used. Separate subsamples were used to create and validate curves. Smoothed percentile curves (3rd to 97th) were created by the Lambda Mu Sigma (LMS) method. The validation sample was used to confirm representativeness of the curves. The new curves were compared with the Lubchenco curves.

RESULTS

Final sample included 257 855 singleton infants (57.2% male) who survived to discharge. Gender-specific weight-, length-, and head circumference-for-age curves were created (n = 130 111) and successfully validated (n = 127 744). Small-for-gestational age and large-for-gestational age classifications using the Lubchenco curves differed significantly from the new curves for each gestational age (all P < .0001). The Lubchenco curves underestimated the percentage of infants who were small-for-gestational-age except for younger girls (< or =36 weeks), for whom it was more likely to be overestimated; underestimated percentage of infants (< or =36 weeks) who were large-for-gestational-age; and overestimated percentage of infants (>36 weeks) who were large-for-gestational-age.

CONCLUSIONS

The Lubchenco curves may not represent the current US population. The new intrauterine growth curves created and validated in this study, based on a contemporary, large, racially diverse US sample, provide clinicians with an updated tool for growth assessment in US NICUs. Research into the ability of the new definitions of small-for-gestational-age and large-for-gestational-age to identify high-risk infants in terms of short-term and long-term health outcomes is needed.