Birth weight categorization according to gestational age does not reflect percentage body fat in term and preterm newborns

Birthweight z-score and fat-free mass at birth predict body composition at 3 years in Danish children born from obese mothers

Aim

We investigated associations between newborn body composition and anthropometry and body composition at 3 years in Danish children born from obese mothers.

Methods

Analyses are based on data from the observational cohort study SKOT II (SKOT; small children's diet and well‐being (Danish)). Body composition at birth and at 3 years was assessed by dual‐energy X‐ray absorptiometry (DXA) scans and bioelectrical impedance analysis (BIA), respectively. Multiple linear regression models were applied to determine associations between newborn body composition and anthropometry and body composition at 3 years.

Results

Birthweight z‐score (BWZ) was positively associated with fat‐free mass (FFM), height, fat‐free mass index (FFMI), fat mass (FM) and fat mass index (FMI) at 3 years. Newborn FFM was positively associated with FFM, height, FFMI and FM at 3 years, and positive trends were seen between newborn FM and FM and FMI at 3 years.

Conclusion

We showed that infants born with a higher BWZ go on to be taller at 3 years. They also grow to be heavier, to which FM and FFM both contribute, independently of linear growth. Additionally, it seems that FFM tracks into early childhood, thus supporting intrauterine programming of later health.

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

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

Construction of China national newborn growth standards based on a large low-risk sample

Most published newborn growth references are based on conventional monitoring data that usually included both low- and high-risk pregnancies. We sought to develop a set of neonatal growth standards constructed from only a large sample of low-risk pregnancies. A total of 24,375 naturally conceived singleton live births with gestational ages of 24–42 weeks were collected in 69 hospitals in thirteen Chinese cities between 2015 and 2018. Unhealthy infants or those with high-risk mother were excluded. Smoothed percentile curves of six anthropometric indicators were established using the Generalized Additive Model for Location, Scale and Shape. The 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentile references for birth weight, length, head circumference, weight/length, body mass index, and ponderal index were calculated for neonates with gestational ages of 24–42 weeks. This set of neonatal growth standards with six anthropometric indicators can provide more tools for growth and nutrition assessment and body proportionality in neonatal clinical practice. These standards might also help to show the differences between growth curves based on low-risk and mixed low- and high-risk pregnancies.

A systematic review indicates an association between birth weight and body fat in childhood

AIM

To summarise the existing evidence regarding the body fat of small or large for gestation subjects, evaluated from birth up to 18 years of age.

METHODS

The PRISMA guidelines were adopted for the current systematic review, including studies having evaluated body fat with bioelectrical impedance analysis, air displacement plethysmography, dual-energy X-ray absorptiometry or magnetic resonance imaging.

RESULTS

A total of 31 studies was included. The balance of evidence suggests that small for gestation infants have decreased fat mass at birth; postnatally they experience increased adiposity. In the long term, however, the evidence is inconclusive, since some studies suggest that foetal-restricted children with increased catch-up growth are at increased risk of fat accumulation, whereas other studies suggest a neutral or even negative association. Large for gestation infants have increased fat mass at birth, but in the long term, they have a lower body fat ratio, especially when they develop a catch-down growth.

CONCLUSION

Some studies suggested that foetal-restricted children with increased catch-up growth are at increased risk of later adiposity, while other studies suggested a neutral or negative association. Given that the evidence is inconclusive, further studies are warranted. Large for gestation subjects have lower body fat when they develop catch-down growth.

Large for Gestational Age and Obesity-Related Comorbidities

Both small for gestational age and large for gestational age (LGA) size at birth are associated with metabolic complications throughout life. The long-term consequences of LGA have been investigated in only a few studies. LGA is thought to be associated with early obesity and metabolic risk. Understanding how LGA can influence later obesity risk is important for pediatric obesity interventions. Pregnant women who are overweight or obese are at high risk of having LGA babies. Infants born LGA are at increased risk of becoming overweight or obese children, adolescents, and young adults and can have an increased risk of metabolic syndrome later in life and giving birth to LGA offspring. Education and intervention for weight control before and during pregnancy should be conducted to prevent LGA births. Particular attention is needed for women of childbearing age who are diabetic and obese, which could be the starting point for lifelong management of obesity.

Soft tissue assessment for fetal growth restriction

Contemporary clinical practice heavily relies on interpretation of population-based birth weight standards to evaluate neonatal nutrition status. Obstetricians have adopted the use of estimated fetal weight in a similar manner to estimate fetal nutritional status. However, most fetal weight prediction models overemphasize skeletal parameters such as biparietal diameter, head circumference, and femur diaphysis length. Although most EFW calculations also include abdominal circumference, this 2D growth parameter is largely defined by liver size and a small rim of subcutaneous fat. Advances in 3D ultrasound imaging and the development of more robust image analysis tools have now made it possible to reliably add a soft tissue component for fetal nutritional assessment. This chapter explains why fetal soft tissue evaluation is clinically relevant, describes different techniques for evaluating these sonographic parameters, and outlines future directions for their practical utility in the care of malnourished fetuses.

Newer Insights Into Fetal Growth and Body Composition

Based on epidemiological and experimental evidence, the origins of childhood obesity and early onset metabolic syndrome can be extended back to developmental processes during intrauterine life. It is necessary to actively investigate antecedent conditions that affect fetal growth by developing reliable measures to identify variations in fetal fat deposition and body composition. Recently, the resolution of ultrasonography has remarkably improved, which enables better tissue characterization and quantification of fetal fat accumulation. In addition, fetal fractional limb volume has been introduced as a novel measure to quantify fetal soft tissue volume, including fat mass and lean mass. Detecting extreme variations in fetal fat deposition may provide further insights into the origins of altered fetal body composition in pathophysiological conditions (i.e., fetal growth restriction or fetal macrosomia), which are predisposed to the metabolic syndrome in later life. Further studies are warranted to determine the maternal or placental factors that affect fetal fat deposition and body composition. Elucidating these factors may help develop clinical interventions for altered fetal growth and body composition, which could potentially lead to primary prevention of the future risk of metabolic dysfunction.

Proportionality indices, geographic altitude, and gestational age in newborns from Jujuy, Argentina

BACKGROUND

There are several different proportionality indices (PRIs) to evaluate size at birth by gestational age (GA). Yet, the explanatory power of alternative PRIs has not been evaluated in highland (HL) populations.

AIM

Evaluate the relative utility of three PRIs, weight to length ratio (W/L), body mass index (BMI), and ponderal index (PI), for assessing nutritional status in newborns (NBs) from highland (HL ≥ 2000 m) and lowland (LL < 2000 m) regions of the Jujuy Province of Argentina.

SUBJECTS AND METHODS

Births were registered by the Ministry of Health (Jujuy, 2009-2014). Data were grouped according to HL and LL altitude groups based on of maternal residence. The main outcome measures were the PRIs W/L ratio, BMI, and PI. Percentiles were generated by the LMS method and compared with references. ANOVAs and Pearson correlations were used to examine the relationship between outcome measures with weight and length by altitude, sex, and GA.

RESULTS

In both altitude zones, W/L and BMI increased with GA, while PI stabilized between 37th and 42th weeks. The LL sample had significantly higher values for all the PRIs from the 37th week of GA. In the HL sample, the 50th percentiles for all three PRIs were lower than the reference. Regardless of GA and altitude level, BMI showed the lowest correlation with length and the higher with the weight.

CONCLUSION

The HL sample of term NBs had lower values for all PRIs compared to their LL counterparts. In both altitude zones, the BMI is the preferred PRI to evaluate the nutritional status.

Differences in omentin-1 levels in term newborns according to birth weight

BACKGROUND

Adipokines are produced by adipose tissue and are involved in metabolic processes. Omentin-1 is an adipokine that has been shown in vitro to possibly be involved in insulin sensitivity modulation. The prenatal stage is a crucial period for development of metabolic diseases in the long term, therefore, small (SGA) and large (LGA) for gestational age newborns have an increased risk of type 2 diabetes and metabolic syndrome later in life.

AIMS

To evaluate the differences in omentin-1 concentrations in umbilical cord blood from healthy term newborns according to birth weight and explore the association between omentin-1 and anthropometry, glucose, insulin and insulin sensitivity.

STUDY DESIGN

This was a secondary analysis of stored umbilical cord blood of term newborns.

SUBJECTS

Newborns classified according to birth weight as SGA (n = 30), adequate for gestational age (AGA) (n = 12) and LGA (n = 34).

OUTCOME MEASURES

An analysis of omentin-1, glucose and insulin were performed.

RESULTS

Differences were found in serum omentin-1 levels (ng/mL) between SGA 328.17 ± 108.04, AGA 253.05 ± 98.25 and LGA 250.91 ± 100.48 (p = 0.009). In the linear regression analysis, the independent variables HOMA-IR, QUICK-I and FGIR were predictors of serum omentin-1 levels (r = 0.175, p = 0.003).

CONCLUSIONS

Omentin-1 cord blood levels have a differentiated behavior according to weight for gestational age with LGA newborns having lower levels and SGA newborns higher levels. HOMA-IR, QUICK-I and FGIR weakly predicted omentin-1 in cord blood, suggesting that omentin-1 possibly has an implication in insulin sensitivity since birth.

Impact of changes in maternal body composition on birth weight and neonatal fat mass in dichorionic twin pregnancies

Background

Although the impact of gestational weight gain (GWG) on birth weight in twin pregnancies has been demonstrated, the specific components of GWG have not been delineated for twin gestations. Fetal body composition has been shown to be modifiable in singleton gestations based on nutritional intervention strategies and may prove to have similar modifications in twin gestations.

Objective

We aimed to determine the relation of maternal body composition changes to birth weight, birth length, and neonatal fat mass (FM) in dichorionic-diamniotic twin pregnancies.

Design

This is a prospective study of 20 women with twin gestations. Comparisons were made between body composition variables during each trimester and for the entire pregnancy and compared with the outcomes of birth weight, neonatal fat percentage, and birth length.

Results

GWG within or above compared with below the IOM recommendations was associated with higher birth weights (P = 0.03, P = 0.04, respectively), but also with higher postpartum weight retention (P = 0.001). Total maternal protein gain over the pregnancy was positively associated with birth weight (P = 0.03). Changes in maternal fat-free mass (FFM), total body water (TBW), and FM from the first to the third trimester were not associated with either birth weight or neonatal FM percentage. However, maternal FM change from the second to the third trimester was significantly correlated to neonatal FM percentage (P = 0.02). Third trimester GWG and total protein gain were positively correlated with neonatal birth length (P = 0.02 and 0.03, respectively). Maternal FFM over all 3 trimesters showed a positive relation with neonatal birth length (P = 0.01).

Conclusions

Significant increases in maternal protein are associated with greater birth weight and neonatal birth length. Protein accretion, in contrast to TBW and FM gains, may be the most critical component of maternal GWG in dichorionic twin gestations.

Individualized Postnatal Growth Trajectories for Preterm Infants

BACKGROUND

Growth of preterm infants is monitored using fetal charts despite individual trajectories being downshifted postnatally by adaptational processes. The study aims to compare different approaches to create individualized postnatal trajectories.

METHODS

Three approaches to achieve growth similar to healthy term infants at 42+0/7 weeks postmenstrual age (PMA) on World Health Organization growth standards (WHOGS) (target weight) were tested by comparing trajectories obtained by: 1) following birth percentiles (Birth-Weight-Percentile Approach); 2) following percentiles achieved at day of life 21 (Postnatal-Percentile Approach); 3) using day-specific fetal median growth velocities starting at day of life 21 (Fetal-Median-Growth Approach [FMGA]). The primary outcome was delta weight (ΔW), defined as difference between target weight (WHOGS) at 42+0/7 weeks and weight predicted by trajectories. The secondary outcome was ΔW vs %fat mass in a cohort of 20 disease-free surviving very low-birth-weight infants.

RESULTS

Birth-Weight-Percentile and Postnatal-Percentile Approach showed high ΔW; FMGA alone reduced ΔW. Introducing a factor to FMGA to reflect the transition to extrauterine conditions (Growth-Velocity Approach [GVA]) minimized ΔW. GVA merged with target and best normalized for body composition related to ΔW.

CONCLUSIONS

GVA provides an evidence-based approach for individualized growth trajectories. GVA is based on physiologic data and that healthy preterm infants adjust their postnatal trajectory below their birth percentile. GVA may reflect a biologic principle because it matches consistently with WHOGS at 42+0/7 weeks for all preterm infants from 24 to 34 weeks. This concept could become a bedside tool to aid clinicians in monitoring growth, guiding nutrition, and minimizing chronic adult disease risks as a consequence of unguided, inappropriate growth.

Association of ultrasound-based measures of fetal body composition with newborn adiposity

BACKGROUND

Newborns exhibit substantial variation in gestational age-adjusted and sex-adjusted fat mass proportion. The antecedent characteristics of fetal body composition that are associated with newborn fat mass proportion are poorly understood.

OBJECTIVE

The aim of this study was to determine whether a composite measure of fetal fat mass is prospectively associated with newborn adiposity.

METHODS

In a longitudinal study of 109 low-risk pregnancies, fetal ultrasonography was performed at approximately 12, 20 and 30 weeks gestation. Estimated fetal adiposity (EFA) was derived by integrating cross-sectional arm and thigh per cent fat area and anterior abdominal wall thickness. Newborn per cent body fat was quantified by Dual Energy X-Ray Absorptiometry. The association between EFA and newborn per cent body fat was determined by multiple linear regression.

RESULTS

After controlling for confounding factors, EFA at 30 weeks was significantly associated with newborn per cent body fat (standardized β = 0.41, p < 0.001) and explained 24.0% of its variance, which was substantially higher than that explained by estimated fetal weight (8.1%). The observed effect was driven primarily by arm per cent fat area.

CONCLUSIONS

A composite measure of fetal adiposity at 30 weeks gestation may constitute a better predictor of newborn per cent body fat than estimated fetal weight by conventional fetal biometry. Fetal arm fat deposition may represent an early indicator of newborn adiposity. After replication, these findings may provide a basis for an improved understanding of the ontogeny of fetal fat deposition, thereby contributing to a better understanding of its intrauterine determinants and the development of potential interventions.

An observational cohort study of weight- and length-derived anthropometric indicators with body composition at birth and 5 mo: the Healthy Start study

Background: Despite widespread use of weight- and length-based anthropometric indexes as proxies for adiposity, little is known regarding the extent to which they correspond with fat mass (FM) or fat-free mass (FFM) during infancy.Objective: This study aimed to examine associations of 3 derived indicators-weight-for-age z score (WFAZ), weight-for-length score (WFLZ), and body mass index z score (BMIZ)-with FM, percentage of FM, and FFM measured by air-displacement plethysmography during the first 5 mo of life.Design: Applying prospectively collected data from 1027 infants in a Colorado prebirth cohort, we used multivariate regression to evaluate associations between the derived indicators and body composition at birth and at 5 mo, and with change (Δ) during follow-up.Results: At birth, all 3 derived indicators were more strongly associated with FFM than with FM. Each unit of WFAZ corresponded with 0.342 kg FFM (95% CI: 0.331, 0.351 kg FFM), compared with 0.121 kg FM (95% CI: 0.114, 0.128 kg FM) (P < 0.0001); similar trends were observed for WFLZ and BMIZ. By 5 mo, WFLZ and BMIZ were more strongly associated with FM than with FFM, whereas WFAZ correlated similarly with the 2 components of body composition. ΔWFLZ and ΔBMIZ were both more strongly related to ΔFM than to ΔFFM; however, a direct comparison of the 2 indexes with respect to change in the percentage of FM indicated that ΔBMIZ was the optimal proxy of adiposity gain (P < 0.0001, pairwise difference).Conclusions: Weight- and length-based indexes are poor surrogates for newborn adiposity. However, at 5 mo, WFLZ and BMIZ are suitable proxies of FM. When assessing adiposity gain, ΔBMIZ is the best indicator of fat accrual during the first 5 postnatal months. This trial was registered at clinicaltrials.gov as NCT02273297.

Prospective association of fetal liver blood flow at 30 weeks gestation with newborn adiposity

BACKGROUND

The production of variation in adipose tissue accretion represents a key fetal adaptation to energy substrate availability during gestation. Because umbilical venous blood transports nutrient substrate from the maternal to the fetal compartment and because the fetal liver is the primary organ in which nutrient interconversion occurs, it has been proposed that variations in the relative distribution of umbilical venous blood flow shunting either through ductus venosus or perfusing the fetal liver represents a mechanism underlying this adaptation.

OBJECTIVE

The objective of the present study was to determine whether fetal liver blood flow assessed before the period of maximal fetal fat deposition (ie, the third trimester of gestation) is prospectively associated with newborn adiposity.

STUDY DESIGN

A prospective study was conducted in a cohort of 62 uncomplicated singleton pregnancies. Fetal ultrasonography was performed at 30 weeks gestation for conventional fetal biometry and characterization of fetal liver blood flow (quantified by subtracting ductus venosus flow from umbilical vein flow). Newborn body fat percentage was quantified by dual energy X-ray absorptiometry imaging at 25.8 ± 3.3 (mean ± standard error of the mean) postnatal days. Multiple regression analysis was used to determine the proportion of variation in newborn body fat percentage explained by fetal liver blood flow. Potential confounding factors included maternal age, parity, prepregnancy body mass index, gestational weight gain, gestational age at birth, infant sex, postnatal age at dual energy X-ray absorptiometry scan, and mode of infant feeding.

RESULTS

Newborn body fat percentage was 13.5% ± 2.4% (mean ± standard error of the mean). Fetal liver blood flow at 30 weeks gestation was significantly and positively associated with newborn total fat mass (r=0.397; P<.001) and body fat percentage (r=0.369; P=.004), but not with lean mass (r=0.100; P=.441). After accounting for the effects of covariates, fetal liver blood flow explained 13.5% of the variance in newborn fat mass. The magnitude of this association was pronounced particularly in nonoverweight/nonobese mothers (prepregnancy body mass index, <25 kg/m²; n=36) in whom fetal liver blood flow explained 24.4% of the variation in newborn body fat percentage.

CONCLUSION

Fetal liver blood flow at the beginning of the third trimester of gestation is associated positively with newborn adiposity, particularly among nonoverweight/nonobese mothers. This finding supports the role of fetal liver blood flow as a putative fetal adaptation underlying variation in adipose tissue accretion.

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.

Physiological adjustment to postnatal growth trajectories in healthy preterm infants

BACKGROUND

International guidelines suggest that growth of preterm infants should match intrauterine rates. However, the trajectory for extrauterine growth may deviate from the birth percentile due to an irreversible, physiological loss of extracellular fluid during postnatal adaptation to extrauterine conditions. To which "new" physiological growth trajectory preterm infants should adjust to after completed postnatal adaptation is unknown. This study analyzes the postnatal growth trajectories of healthy preterm infants using prospective criteria defining minimal support, as a model for physiological adaptation.

METHODS

International, multi-center, longitudinal, observational study at five neonatal intensive care units (NICUs). Daily weights until day of life (DoL) 21 of infants with undisturbed postnatal adaptation were analyzed (gestational ages: (i) 25-29 wk, (ii) 30-34 wk).

RESULTS

981 out of 3,703 admitted infants included. Maximum weight loss was 11% (i) and 7% (ii) by DoL 5, birth weight regained by DoL 15 (i) and 13 (ii). Infants transitioned to growth trajectories parallel to Fenton chart percentiles, 0.8 z-scores below their birth percentiles. The new trajectory after completed postnatal adaptation could be predicted for DoL 21 with R(2) = 0.96.

CONCLUSION

This study provides a robust estimate for physiological growth trajectories of infants after undisturbed postnatal adaptation. In the future, the concept of a target postnatal trajectory during NICU care may be useful.

BMI at birth and overweight at age four

BACKGROUND

Extensive investigation has established that an elevated weight at birth is associated with subsequent obesity and obesity related negative health outcomes. The significance of overweight at birth, however, remains ill-defined. Historically, it has been difficult to approximate adiposity in infancy in a way that is both simple and meaningful. Body-mass-index (BMI) growth charts for children younger than two years of age only became available in 2006 when published by the WHO.

METHODS

This retrospective cohort analysis utilised anthropometric data extracted from the electronic medical record of a large integrated healthcare system in North Carolina. BMI and weight-for-age (WFA) >85% of WHO growth charts measured newborn overweight and macrosomia respectively. Logistic regression models assessed the associations between newborn macrosomia and overweight and overweight at 4 years of age, as well as associations with maternal BMI. Models included demographic data, gestational age, and maternal diabetes status as covariates.

RESULTS

Both BMI and WFA >85% at birth were significantly associated with overweight at age 4 years. However, the greater odds of overweight was associated with newborn BMI >85%, with an adjusted odds ratio (AOR) of 2.08 (95% confidence interval [CI]: 1.4-3.08) versus 1.57 (95% CI: 1.08-2.27). Maternal obesity was also more robustly correlated with newborn BMI >85%, AOR of 4.14 (95% CI: 1.6-10.7), than with newborn WFA >85%, AOR of 3.09 (95% CI: 1.41-6.77).

CONCLUSIONS

BMI >85% at birth is independently associated with overweight at 4 years. Newborn overweight is perhaps superior to newborn macrosomia in predicting overweight at age 4.

Working group reports: evaluation of the evidence to support practice guidelines for nutritional care of preterm infants-the Pre-B Project

The "Evaluation of the Evidence to Support Practice Guidelines for the Nutritional Care of Preterm Infants: The Pre-B Project" is the first phase in a process to present the current state of knowledge and to support the development of evidence-informed guidance for the nutritional care of preterm and high-risk newborn infants. The future systematic reviews that will ultimately provide the underpinning for guideline development will be conducted by the Academy of Nutrition and Dietetics' Evidence Analysis Library (EAL). To accomplish the objectives of this first phase, the Pre-B Project organizers established 4 working groups (WGs) to address the following themes: 1) nutrient specifications for preterm infants, 2) clinical and practical issues in enteral feeding of preterm infants, 3) gastrointestinal and surgical issues, and 4) current standards of infant feeding. Each WG was asked to 1) develop a series of topics relevant to their respective themes, 2) identify questions for which there is sufficient evidence to support a systematic review process conducted by the EAL, and 3) develop a research agenda to address priority gaps in our understanding of the role of nutrition in health and development of preterm/neonatal intensive care unit infants. This article is a summary of the reports from the 4 Pre-B WGs.

Measurement of abdominal circumference in preterm infants

BACKGROUND

Body weight, length and head and thoracic circumference are routinely measured in obstetric and neonatal departments. Reference values for these measurements have been established for the neonatal population. Neonatal abdominal circumference is not routinely measured, and no reference values for this measurement have been determined. To evaluate the increase in abdominal circumference in newborns with abdominal pathology such as necrotizing enterocolitis, information about normal abdominal circumference in healthy neonates shortly after birth is needed. The aim of this study was to determine the correlation between abdominal circumference and birth weight by measuring the abdominal circumference of premature neonates soon after birth.

METHODS

Abdominal circumference was measured within 30 min of birth in 220 neonates born between 23 and 35 weeks' gestation.

RESULTS

There was no statistically significant difference in abdominal circumference between boys and girls in the study population. A specific formula for estimating normal abdominal circumference was developed: y = 0.0053x + 14.83 (y = abdominal circumference in cm; x = body weight in g; 0.0053 = regression coefficient; 14.83 = regression constant).

CONCLUSION

A positive linear correlation between abdominal circumference and birth weight was found in infants at birth. The correlation can be summarized as a linear regression equation. Further studies are needed to investigate possible factors associated with abdominal circumference in fed versus unfed preterm infants.

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.

The impact of abnormal glucose tolerance and obesity on fetal growth

OBJECTIVE

Factors linked with insulin resistance were examined for their association with large-for-gestational-age (LGA) infant birth weight and gestational diabetes.

STUDY DESIGN

Data came from a longitudinal cohort study of 2,305 subjects without overt diabetes, analyzed using multinomial logistic and linear regression.

RESULTS

High maternal BMI (OR = 1.53 (1.11, 2.12)), height (1.98 (1.62, 2.42)), antidepressant use (1.71 (1.20, 2.44)), pregnancy weight-gain exceeding 40 pounds (1.79 (1.25, 2.57)), and high blood sugar (2.68, (1.53, 5.27)) were all positively associated with LGA birth. Strikingly, the difference in risk from diagnosed and treated gestational diabetes compared to women with a single abnormal glucose tolerance test (but no diagnosis of gestational diabetes) was significant (OR = 0.65, p = 0.12 versus OR = 2.84, p < 0.01). When weight/length ratio was used instead, different factors were found to be significant. BMI and pregnancy weight-gain were found to influence the development of gestational diabetes, through an additive interaction.

CONCLUSIONS

High prepregnancy BM, height, antidepressant use, pregnancy weight-gain exceeding 40 pounds, and high blood sugar were associated with LGA birth, but not necessarily infant weight/length ratio. An additive interaction between BMI and pregnancy weight-gain influenced gestational diabetes development.

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.

Antenatal predictors and body composition of large-for-gestational-age newborns: perinatal health outcomes

OBJECTIVE

To compare body composition of large-for-gestational-age (LGA) with appropriate-for-gestational-age (AGA) newborns and to identify antenatal predictors of LGA.

STUDY DESIGN

This cross-sectional study included 536 term, singleton infants. Anthropometric measurements were performed within 48 h of birth and included determination of body fat percentage (%BF) by air displacement plethysmography. Associations were investigated using logistic regression.

RESULT

LGA infants had greater %BF (P<0.001) compared with AGA infants. Significant predictors of LGA infants included parity (odds ratio (OR)=1.98, (95% confidence interval (CI) 1.00, 4.02)), paternal height (OR=1.08, (95% CI 1.03, 1.14)), maternal pregravid weight (65 to 74.9 kg: OR=2.77, (95% CI 1.14, 7.06)) and gestational weight gain (OR=1.09, 95% CI (1.03, 1.16)). Gestational diabetes mellitus was not associated with LGA infants (P=0.598).

CONCLUSION

Paternal height, parity, maternal pregravid weight and gestational weight gain were strongly associated with LGA infants. These results may allow early prediction and potential modification, thereby optimising clinical outcomes.

Newborn regional body composition is influenced by maternal obesity, gestational weight gain and the birthweight standard score

AIM

This study investigated whether newborn body composition is influenced by prepregnancy obesity and gestational weight gain (GWG) and explored any associations between body composition and birthweight standard score (z-score), categorised by size for gestational age.

METHODS

We recruited 231 obese and 80 normal weight mothers and their newborn infants and assessed the babies' body composition using dual-energy X-ray absorptiometry.

RESULTS

The total and abdominal fat masses of infants born to mother who were obese before pregnancy were 135 g (p < 0.001) and 18 g (p < 0.001) higher than the offspring of normal weight mothers. The infants' fat mass increased by 11 g (p < 0.001) for every kilogram of GWG. There were no associations between prepregnancy obesity and fat-free mass. The fat percentage was significantly higher in infants who were large for gestational age (15.3%) than small for gestational age (5.2%) and appropriate for gestational age (9.8%) (p < 0.001). Lower birthweight z-score was associated with a higher proportion of abdominal fat mass (p = 0.009).

CONCLUSION

Infants born to obese mothers had higher fat mass at birth, with abdominal fat accumulation. Low birthweight was associated with a lower crude abdominal fat mass, but a higher proportion of total fat mass placed abdominally.

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.

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.

Target fortification of breast milk with fat, protein, and carbohydrates for preterm infants

OBJECTIVES

Fortification of breast milk is an accepted practice for feeding very low birth weight infants, however, fixed dosage enhancement does not address variations in native breast milk. This could lead to deficiencies in calories and macronutrients. We therefore established the infrastructure for target fortification in breast milk by measuring and adjusting fat, protein, and carbohydrate content daily. We analyzed nutrient intake, growth, and safety variables.

STUDY DESIGN

Each 12-hour batch of breast milk was analyzed using near-infrared spectroscopy. Macronutrients were individually added to routine fortification to achieve final contents for fat (4.4 g), protein (3 g), and carbohydrates (8.8 g) (per 100 mL). Fully breast milk fed healthy very low birth weight infants (<32 weeks) were fed the fortified breast milk for at least 3 weeks. Matched pair analysis of 20 infants fed routinely fortified breast milk was performed using birth weight, gestational age, and postnatal age.

RESULTS

All 650 pooled breast milk samples required at least 1 macronutrient adjusted. On average, 0.3 ± 0.4 g of fat, 0.7 ± 0.2 g of protein, and 1.2 ± 0.2 g of carbohydrate were added. Biochemistry was normal in the 10 target fortified infants (birth weight: 860 ± 309 g, 26.3 ± 1.6 weeks gestational age); weight gain was 19.9 ± 2.7 g/kg/d; and milk intake was 147 ± 5 mL/kg/d (131 ± 16 kcal/kg/d). Osmolality of fortified breast milk was 436 ± 13 mOsmol/kg. Matched pair analysis of infants indicated a higher milk intake (155 ± 5 mL/kg/d) but similar weight gain (19.7 ± 3.3 g/kg/d). No adverse event was observed. The linear relationship between milk intake and weight gain observed in study babies but not seen in matched controls may be related to the variable composition of breast milk.

CONCLUSIONS

Daily target fortification can be safely implemented in clinical routine and may improve growth.

Birth and developmental correlates of birth weight in a sample of children with potential sensory processing disorder

Background

Most research examining birth history (i.e. related birth complications) and developmental milestone achievement follow outcomes for infants at-risk with very specific birth weight categories and gestational age classifications. The purpose of this study was to examine how birth weight relates to infants’ birth histories and developmental milestone achievement when they fall into a variety of birth weight and gestational age categories.

Methods

In the current study, we examined birth histories and onset ages for developmental milestones by analyzing a convenience sample of anonymous existing data from 663 developmental histories completed by parents at the time of an initial evaluation at a pediatric outpatient occupational therapy clinic. Infants fell into 3 birth weight categories; low birth weight (LBW), normal birth weight (NBW), and high birth weight (HBW) and 3 gestational age classifications considered with birth weight; small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA).

Results

NBW, AGA, and SGA infants with related birth complications had lower birth weights than infants without birth complications. Larger birth weights were associated with earlier ages for independent sitting for HBW infants, earlier ages for eating solids for NBW infants, and earlier walking onsets for LBW and NBW infants. Higher birth weights were also linked with rolling at a younger age for LGA infants, earlier walking and speaking words for AGA infants, and sooner independent sitting for SGA and AGA infants.

Conclusions

Our findings suggest that birth weight and gestational age categories provide unique insights into infants’ birth history and developmental milestone achievement.

The relationship of newborn adiposity to fetal growth outcome based on birth weight or the modified neonatal growth assessment score

OBJECTIVES

(1) Develop reference ranges of neonatal adiposity using air displacement plethysmography. (2) Use new reference ranges for neonatal adiposity to compare two different methods of evaluating neonatal nutritional status.

METHODS

Three hundred and twenty-four normal neonates (35-41 weeks post-menstrual age) had body fat (%BF) and total fat mass (FM, g) measured using air displacement plethysmography shortly after delivery. Results were stratified for 92 of these neonates with corresponding fetal biometry using two methods for classifying nutritional status: (1) population-based weight percentiles; and (2) a modified neonatal growth assessment score (m(3)NGAS(51)).

RESULTS

At the 50th percentile, %BF varied from 7.7% (35 weeks) to 11.8% (41 weeks), while the corresponding 50th percentiles for total FM were 186-436 g. Among the subset of 92 neonates, no significant differences in adiposity were found between small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA) groups using population-based weight standards. Classification of the same neonates using m(3)NGAS(51) showed significant differences in mean %BF between corresponding groups.

CONCLUSIONS

Population-based weight criteria for neonatal nutritional status can lead to misclassifications on the basis of adiposity. A neonatal growth assessment score, that considers the growth potential of several anatomic parameters, appears to more effectively classify under- and over-nourished newborns.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Gestational age dependent content, composition and intrauterine accretion rates of fatty acids in fetal white adipose tissue

BACKGROUND

Little is known about the gestational age (GA) dependent content, composition and intrauterine accretion rates of fatty acids (FA) in fetal white adipose tissue (WAT).

OBJECTIVE & DESIGN

To acquire this information, we collected abdominal subcutaneous WAT samples from 40 preterm and term fetuses. Their GA ranged from 22 to 43 weeks. FA were expressed as mg/g wet WAT and g/100g FA (g%). Intrauterine WAT FA accretion rates were estimated for appropriate (AGA) and large (LGA) for gestational age infants.

RESULTS

From 25 to 40 weeks gestation, saturated-FA (SAFA) increased from 83 to 298 mg/g WAT and monounsaturated-FA (MUFA) from 83 to 226 mg/g WAT, while polyunsaturated-FA (PUFA) increased insignificantly from 18.0 to 23.2 mg/g WAT. As percentages of total FA, SAFA increased from 46 to 55 g%, MUFA decreased from 44 to 41 g%, and PUFA from 10.3 to 4.26 g%. Docosahexaenoic (DHA) and arachidonic acid (AA) accretion rates in WAT during the 3rd trimester for AGA infants were 88 and 193 mg/week, respectively. Contemporaneous DHA and AA accretion rates for 4500 g LGA infants were 184 and 402 mg/week, respectively. Compared to the whole 3rd trimester, increment rates during the last 5 weeks of gestation were about 2-fold higher.

CONCLUSION

FA accretion rates, notably those of DHA and AA, may be important for designing nutritional regiments for preterm infants. The current WAT-DHA and WAT-AA accretion rates are considerably lower than previously reported in the literature.

Fetal intrauterine whole body linoleic, arachidonic and docosahexaenoic acid contents and accretion rates

INTRODUCTION

There is no information on the whole body fatty acid (FA) contents of preterm or term infants, although scattered information on the FA-composition of many organs is available.

MATERIAL AND METHODS

We collected data on the weights, lipid contents and FA-compositions of the quantitatively most important fetal organs of appropriate for gestational age (AGA) Western infants. From these we estimated the total body contents of linoleic (LA), arachidonic (AA) and docosahexaenoic (DHA) acids at 25, 35 and 40 weeks of gestation.

RESULTS

Western infants accrete FA in the order of LA>AA>DHA at all stages during pregnancy and the highest accretion rates are reached in the last 5 weeks of gestation, i.e. 342 mg LA, 95 mg AA and 42 mg DHA/day. At term, most of the infant's LA, AA and DHA is located in adipose tissue (68, 44 and 50%, respectively), with substantial amounts of LA also located in skeletal muscle (17%) and skin (13%); of AA in skeletal muscle (40%) and brain (11%); and of DHA in brain (23%) and skeletal muscle (21%). The term AGA infant has accreted about 21 g LA, 7.5 g AA and 3 g DHA, which constitutes a gap of 12 g LA, 3.3 g AA and 1.5 g DHA compared to a 35 weeks old AGA infant.

CONCLUSION

The current fetal LA, AA and DHA pool sizes and accretion rates may especially be useful to estimate the preterm infant's requirements and the maternal LCP needs during pregnancy. Since they derive from populations with typically Western diets they do not necessarily reflect 'optimality' or 'health'.

A nutritional program to improve outcome of very low birth weight infants

BACKGROUND & AIMS

The growth of very low birth weight infants does not match intrauterine trajectories, likely due to inappropriate caloric intake. We therefore investigated whether modification of the standard nutritional schedule can impact postnatal growth.

METHODS

We introduced a set of evidence-based strategies in a study group of infants (n = 123): 1) higher maximum intake of intravenous amino acids and lipids; 2) prioritisation of earlier enteral feeding; 3) faster attainment of full enteral feeds; 4) daily adjustment of enteral feeds according to growth trajectory; and 5) utilisation of an electronic pre-structured prescription ordering system that tracks individual growth and energy intake. These infants were compared with a control group (n = 115) in a pre/post retrospective cohort study.

RESULTS

The study group achieved a higher caloric intake, attained full enteral feeds 5 days earlier, and returned to their birth weight more rapidly than the control group. At 36 weeks postmenstrual age, infants who had been born at <30 weeks were heavier (Δ260 g) but had a similar percentage fat mass. Those born at <28 weeks had a larger head circumference (Δ1.4 cm) and lower sepsis rate (7.8%).

CONCLUSIONS

Optimization of early postnatal nutrition and daily adjustment of milk intake according to weight gain improved growth, without any unfavourable outcomes for body composition and neurodevelopmental follow-up.

Gender- and gestational age-specific body fat percentage at birth

BACKGROUND

There is increasing evidence that in utero growth has both immediate and far-reaching influence on health. Birth weight and length are used as surrogate measures of in utero growth. However, these measures poorly reflect neonatal adiposity. Air-displacement plethysmography has been validated for the measurement of body fat in the neonatal population.

OBJECTIVE

The goal of this study was to show the normal reference values of percentage body fat (%BF) in infants during the first 4 days of life.

METHODS

As part of a large population-based birth cohort study, fat mass, fat-free mass, and %BF were measured within the first 4 days of life using air-displacement plethsymography. Infants were grouped into gestational age and gender categories.

RESULTS

Of the 786 enrolled infants, fat mass, fat-free mass, and %BF were measured in 743 (94.5%) infants within the first 4 days of life. %BF increased significantly with gestational age. Mean (SD) %BF at 36 to 37⁶/⁷ weeks' gestation was 8.9% (3.5%); at 38 to 39 weeks' gestation, 10.3% (4%); and at 40 to 41⁶/⁷ weeks' gestation, 11.2% (4.3%) (P < .001). Female infants had significantly increased mean (SD) %BF at 38 to 39⁶/⁷ (11.1% [3.9%] vs 9.8% [3.9%]; P = .012) and at 40 to 41⁶/⁷ (12.5% [4.4%] vs 10% [3.9%]; P < .001) weeks' gestation compared with male infants. Gender- and gestational age-specific centiles were calculated, and a normative table was generated for reference.

CONCLUSION

%BF at birth is influenced by gestational age and gender. We generated accurate %BF centiles from a large population-based cohort.

Newborn adiposity by body mass index predicts childhood overweight

OBJECTIVE

To evaluate the association between adiposity at birth and in infancy with overweight at age 5 years. This study hypothesizes that adiposity at birth as approximated by body mass index (BMI) predicts childhood fatness.

METHODS

Anthropomorphic data from birth to 5 years were used to calculate BMI percentiles. Multiple logistic regression assessed the association between BMI percentile > or =85% at 2 weeks and BMI percentile > or =85% at 6, 12, 36, and 60 months.

RESULTS

Elevated BMI at age 2 weeks > or =85th percentile was associated with significant increases in risk of overweight at 6, 12, 36, and 60 months of age. Infants with a BMI at age 2 weeks > or =85th percentile had an adjusted odds ratio of 3.42 (95% confidence interval [CI] = 1.79, 6.50) and an adjusted risk ratio of 2.12 (95% CI = 1.71, 2.61) of being overweight at 60 months of age.

CONCLUSIONS

Adiposity at birth as approximated by BMI is a significant predictor of overweight at 5 years.

Subcutaneous fat stores related to weight in full-term neonates

BACKGROUND

Subcutaneous fat stores in newborns have been related to weight (W) and skinfolds (SK); both are influenced by gestational age (GA) and there are few studies analysing the association between them.

AIM

The present study assessed fat storage in term newborns that are appropriately nourished.

SUBJECTS

Subjects were 1259 singleton term newborns, with appropriate weight for GA.

METHODS

A cross-sectional observational study was utilized where weight, length, tricipital skinfold (TSK), subscapular skinfold (SSK) and mid upper arm (MUA) circumference were measured at birth. MUA areas and the TSK/W and SSK/W ratios were calculated. Data were analysed according to gender and GA.

RESULTS

Weight and length were higher in males, while TSK, SSK, MUA fat area, MUA fat percentage, TSK/W and SSK/W were higher in females. Weight and length increased with GA in both genders. SK did not increase with GA, except the TSK in males. The TSK/W and SSK/W ratios decreased significantly with GA age in both genders. Percentiles of TSK/W and SSK/W ratios are presented.

CONCLUSION

The study provides a new perspective to the idea that fat storage increases continuously during the last period of gestation. The data presented showed that this phenomenon is not clearly demonstrated for full-term infants with appropriate weight for GA.

Maturational pharmacokinetics of single intravenous bolus of propofol

BACKGROUND

Our aim was to document propofol pharmacokinetics in preterm and term neonates following a single intravenous bolus and compare these estimates with pharmacokinetics findings in toddlers and young children.

METHODS

Newly collected observations following intravenous bolus administration of propofol in preterm and term neonates (n = 9) were compared with earlier reported pharmacokinetic estimates in toddlers and young children. Data are reported by median and range. Mann-Whitney U-test or correlation was used to analyze differences in pharmacokinetic findings between neonates, toddlers and young children.

RESULTS

Concentration-time profiles obtained were interpreted by two-stage analysis as a three compartment open model in nine neonates with a median weight of 2.51 (range 0.91-3.8) kg and a median postmenstrual age (PMA) of 36 (range 27-43) weeks. Median clearance (CL) was 13.6 (range 3.7-78.2) ml.min(-1).kg(-1) and median apparent volume of distribution at steady state (V(ss)) was 3.7 (1.33-7.96) l.kg(-1). Following allometric scaling and standardization to 70 kg, median CL was 442 (range 97-2184) ml.min(-1).70 kg(-1). Compared with earlier reported observations in toddlers and children, median clearance (kg.min(-1)) was significantly lower in neonates (P < 0.01) and these differences remained significant after allometric scaling (70 kg.min(-1)) while V(ss) (l.kg(-1)) was significantly lower in neonates (P < 0.01).

CONCLUSIONS

Propofol disposition is significantly different in neonates compared with toddlers and young children, reflecting both ontogeny and differences in body composition. Based on the reduced clearance of propofol, a longer recovery time is more likely to occur in neonates.