Background: The BMI z-score is a standardized measure of weight status and weight change in children and adolescents. BMI z-scores from various growth references are often considered comparable, and differences among them are underappreciated. Methods: This study reanalyzed data from a weight management clinical study of liraglutide in pubertal adolescents with obesity using growth references from CDC 2000, CDC Extended, World Health Organization (WHO), and International Obesity Task Force. Results: BMI z-score treatment differences varied 2-fold from -0.13 (CDC 2000) to -0.26 (WHO) overall and varied almost 4-fold from -0.05 (CDC 2000) to -0.19 (WHO) among adolescents with high baseline BMI z-score. Conclusions: Depending upon the growth reference used, BMI z-score endpoints can produce highly variable treatment estimates and alter interpretations of clinical meaningfulness. BMI z-scores cited without the associated growth reference cannot be accurately interpreted.

OBJECTIVE: To investigate the association between infant mortality and birth weight using estimated fetal weight (EFW) versus birth-weight charts, by gestational age (GA).
METHODS: This nationwide population-based study used data from the Finnish Medical Birth Register from 2006 to 2016 on non-malformed singleton live births at 24-41+6 weeks of gestation (N = 563 630). The outcome was death in the first year of life. Mortality risks by birth-weight z score, defined as a continuous variable using Maršál\'s EFW and Sankilampi\'s birth-weight charts, were assessed using generalized additive models by GA (24-27+6, 28-31+6, 32-36+6, 37-38+6, 39-41+6 weeks). We calculated z score thresholds associated with a two- and three-fold increased risk of infant death compared with newborns with a birth weight between 0 and 0.675 standard deviations.
RESULTS: The z score thresholds (with corresponding centiles in parentheses) associated with a two-fold increase in infant mortality were: -3.43 (<0.1) at 24-27+6 weeks, -3.46 (<0.1) at 28-31+6 weeks, -1.29 (9.9) at 32-36+6 weeks, -1.18 (11.9) at 37-38+6 weeks, and - 1.34 (9.0) at 39-41+6 weeks according to the EFW chart. These values were - 2.43 (0.8), -2.62 (0.4), -1.34 (9.0), -1.37 (8.5), and - 1.43 (7.6) according to the birth-weight chart.
CONCLUSIONS: The association between birth weight and infant mortality varies by GA whichever chart is used, suggesting that different thresholds for the screening of growth anomalies could be used across GA to identify high-risk newborns.

BACKGROUND: Growth charts are an important method for evaluating a child\'s health, growth, and nutritional status. It is essential to monitor the growth of children and adolescents using growth charts.
OBJECTIVE: To present body mass index (BMI)-for-age references reflecting children\'s growth in Shanxi. We also compare our new data with growth references of other cities of China and World Health Organization (WHO) growth standards.
METHODS: A stratified cluster random sampling method was used to recruit 5461 children and adolescents aged 6-17 years. Height and weight were measured and BMI was calculated. The LMS method was used to calculate the percentile values of body mass index by sex and age. Smoothed BMI-for-age growth curves were presented for both sexes and compared with reference data from other cities of China and WHO.
RESULTS: BMI centiles increased with age but with different patterns in both boys and girls. The centile curves from the 3rd to the 50th had a slight increase, while a sharp increase was seen from 11 to 17 years in boys and from 6 to 14 years in girls in the higher centiles. In comparison with other cities of China, the values for the 50th percentile are higher than those reported for children from China 2009, Shanghai, Changsha and China 2010 in both sexes. In comparison with WHO growth references, Chinese girls and boys had higher values in all percentiles, whereas curves of girls look roughly the same. The medians for BMI in Shanxi increase linearly from 6 to 17 years in boys.
CONCLUSIONS: The BMI percentiles of children aged 6-17 years in Shanxi differed significantly from the growth reference curves of other cities of China and WHO. Recommending the provision of BMI reference curves for local children and adolescents to assess their growth and development and monitor their nutritional status. Early detection of overweight and obesity in children provides a scientific basis for the prevention and control of overweight and obesity in children.

UNASSIGNED: The overarching aim of this study was to evaluate the Norwegian guidelines for growth monitoring using routinely collected data from healthy children up to five years of age. We analysed criteria for both status (size for age) and change (centile crossing) in growth.
UNASSIGNED: Longitudinal data were obtained from the electronic health record (EHR) at the well-baby clinic for 2130 children included in the Bergen growth study 1 (BGS1). Measurements of length, weight, weight-for-length, body mass index (BMI) and head circumference were converted to z-scores and compared with the World Health Organization (WHO) growth standards and the national growth reference.
UNASSIGNED: Using the WHO growth standard, the proportion of children above +2SD was generally higher than the expected 2.3% for all traits at birth and for length at all ages. Crossing percentile channels was common during the first two years of life, particularly for length/height. By the age of five years, 37.9% of the children had been identified for follow-up regarding length/height, 33% for head circumference and 13.6% for high weight-for-length/BMI.
UNASSIGNED: The proportion of children beyond the normal limits of the charts is higher than expected, and a surprisingly large number of children were identified for rules concerning length or growth in head circumference. This suggests the need for a revision of the current guidelines for growth monitoring in Norway.

Growth chart is a valuable clinical tool to monitor the growth and nutritional status of children. A growth chart widely used in China is based on the merged data sets of national surveys in 2005. We aimed to establish an up-to-date, complete growth curve for urban Chinese children and adolescents with a full range of ages.
Using data collected in a large-scale, cross-sectional study (Prevalence and Risk factors for Obesity and Diabetes in Youth (PRODY), 2017-2019), we analyzed 201,098 urban children aged 3 to 18 years from 11 provinces, autonomous regions, and municipalities that are geographically representative of China. All participants underwent physical examinations. Sex-specific percentiles of height-for-age and weight-for-age were constructed by Generalized Additive Models for Location Scale and Shape (GAMLSS) model. We also compared the median values of height-for-age or weight-for-age between our growth chart and the established growth reference using Welch-Satterthwaite T-Test.
Consistent with the established growth reference, we observed that the P50 percentile of height-for-age reached plateaus at the age of 15 years (172 cm) and 14 years (160 cm) for boys and girls, respectively. In addition, boys aged 10 ~ 14 years and girls aged 10 ~ 12 years exhibited the most dramatic weight difference compared to those of other age groups (19.5 kg and 10.3 kg, respectively). However, our growth chart had higher median values of weight-for-age and height-for-age than the established growth reference with mean increases in weight-for-age of 1.36 kg and 1.17 kg for boys and girls, respectively, and in height-for-age of 2.9 cm and 2.6 cm for boys and girls, respectively.
Our updated growth chart can serve as a reliable reference to assess the growth and nutritional status in urban Chinese children throughout the entire childhood.

UNASSIGNED: The INTERGROWTH-21st preterm postnatal growth standards (IPPGS) have increasingly been used to evaluate the growth of preterm infants worldwide. However, the validity of IPPGS\'s application to specific preterm populations remains controversial. This retrospective cohort study aimed to formulate reference growth charts for a preterm cohort in northern China and compare them to the IPPGS.
UNASSIGNED: A total of 1,827 healthy preterm infants with follow-up visits before 70 weeks of postmenstrual age (PMA) were retrospectively sampled from a preterm cohort (N = 2,011) born between 1 January 2011 and 28 February 2021, at the First Affiliated Hospital of Shandong First Medical University. Using the Generalized Additive Models for Location, Scale, and Shape method, 5,539 sets of longitudinal data were used to construct percentile and Z-score charts of length, weight, and head circumference (HC) at 40-64 weeks of PMA. Z-scores of length, weight, and HC (LAZ, WAZ, and HCZ) before 64 weeks were calculated using the IPPGS. Differences in the 50th percentile values between preterm infants and IPPGS (dLength, dWeight, and dHC) were calculated. Z-scores were assigned to six PMA clusters: 40-44, 44-48, 48-52, 52-56, 56-60, and 60-64 weeks for comparison between sexes.
UNASSIGNED: For eligible infants, the mean PMA and weight at birth were 33.93 weeks and 2.3 kg, respectively. Boys, late preterm infants, twins, and infants with exclusively breastfeeding accounted for 55.8, 70.6, 27.8, and 45.9%, respectively. Compared to IPPGS, preterm infants were longer and heavier, especially for dLength in girls (range, 2.19-2.97 cm), which almost spanned the 50th and 90th percentiles of IPPGS. The dHC tended to narrow with PMA for both sexes. The mean LAZ, WAZ, and HCZ of both sexes at all PMA clusters were >0, especially for LAZ and WAZ (about 1.0 relative to IPPGS), indicating higher levels than the IPPGS at 40-64 weeks. Girls had larger LAZ at each PMA cluster, larger WAZ at 40-44 weeks, and lower HCZ after 56 weeks than boys. HCZ declined with PMA for both sexes.
UNASSIGNED: Postnatal growth of this preterm cohort was considerably higher than that of the IPPGS at 40-64 weeks of PMA with sex differences.

BACKGROUND: Early postnatal growth monitoring and nutrition assessment for preterm infants is a public health and clinical concern. We aimed to establish a set of postnatal growth monitoring curves of preterm infants to better help clinicians make in-hospital and post-discharge nutrition plan of these vulnerable infants.
METHODS: We collected weight, length and head circumference data from a nationwide survey in China between 2015 and 2018. Polynomial regression and the modified LMS methods were employed to construct the smoothed weight, length and head circumference growth curves.
RESULTS: We established the P3, P10, P25, P50, P75, P90, P97 reference curves of weight, length and head circumference that allowed for continuous use from 24 weeks of preterm birth to 50 weeks and developed a set of user-friendly growth monitoring charts. We estimated approximate ranges of weight gain per day and length and head circumference gains per week.
CONCLUSIONS: Our established growth monitoring curves, which can be used continuously without correcting gestational age from 24 weeks of preterm birth to 50 weeks, may be useful for assessment of postnatal growth trajectories, definition of intrauterine growth retardation at birth, and classification of early nutrition status for preterm infants.

OBJECTIVE: To provide updated growth references for Japanese children from birth to 6 years of age, for use in both growth monitoring and child care.
METHODS: We analysed data from two national representative surveys that provided cross-sectional data on 3000 areas in the 2005 national census and longitudinal data from 136 hospitals. Growth references for length/height, weight, head circumference and chest circumference were constructed using the lambda-mu-sigma (LMS) method, with estimates of the L, M and S parameters. These updated values were then compared with growth references published by the World Health Organization.
RESULTS: The 3rd, 50th and 97th smoothed percentile values of length/height, weight, head circumference and chest circumference for boys and girls from birth to 6 years are presented. The comparisons show some large differences in median measurements between the charts.
CONCLUSIONS: Our growth references are based on a current, nationally representative sample of Japanese children. The results provide deep insight into child growth from a historical, ethnic and environmental point of view.

Growth reference centile charts are widely used in child health to assess weight, height and other age-varying measurements. The centiles are easy to construct from reference data, using the LMS method or GAMLSS (Generalised Additive Models for Location Scale and Shape). However, there is as yet no clear guidance on how to design such studies, and in particular how many reference data to collect, and this has led to study sizes varying widely. The paper aims to provide a theoretical framework for optimally designing growth reference studies based on cross-sectional data. Centiles for weight, height, body mass index and head circumference, in 6878 boys aged 0-21 years from the Fourth Dutch Growth Study, were fitted using GAMLSS. The effect on precision of varying the sample size and the distribution of measurement ages (sample composition) was explored by fitting a series of GAMLSS models to simulated data. Sample composition was defined as uniform on the ageλ scale, where λ was chosen to give constant precision across the age range. Precision was measured on the z-score scale, and was the same for all four measurements, with a standard error of 0.041 z-score units for the median and 0.066 for the 2nd and 98th centiles. Compared to a naïve calculation, the process of smoothing the centiles increased the notional sample size two- to threefold by \'borrowing strength\'. The sample composition for estimating the median curve was optimal for λ=0.4, reflecting considerable over-sampling of infants compared to children. However, for the 2nd and 98th centiles, λ=0.75 was optimal, with less infant over-sampling. The conclusion is that both sample size and sample composition need to be optimised. The paper provides practical advice on design, and concludes that optimally designed studies need 7000-25,000 subjects per sex.

The aim is to determine the disparity between the overweight and obesity prevalence of Chinese American school-aged children and adolescents as measured by the Centers for Disease Control and Prevention (CDC) growth reference and the prevalence as measured by international and ethnic-specific-growth references.
This retrospective, cross-sectional study measured overweight and obesity prevalence among a paediatric population using the CDC, International Obesity Task Force (IOTF), World Health Organization (WHO) and an ethnic Chinese growth curve.
A community health centre in New York City, USA.
Chinese American children aged 6-17 years in 2017 (N 9160).
The overweight prevalence was 24 % (CDC), 23 % (IOTF), 30 % (WHO) and 31 % (China). The obesity prevalence was 10 % (CDC), 5 % (IOTF), 10 % (WHO) and 10 % (China). When disaggregated by age and sex, the difference was the most prominent in girls; using the China reference compared with using the CDC reference almost doubles the overweight prevalence (school-aged: 31 v. 17 %, P < 0·001, adolescent: 27 v. 14 %, P < 0·001) and the obesity prevalence (school-aged: 11 v. 5 %, P < 0·001, adolescent: 7 v. 4 %, P < 0·001).
Use of the CDC reference compared with the Chinese ethnic-specific reference results in lower overweight and obesity prevalence in Chinese American girls. Almost half of the girls who were overweight and half of the girls who were obese were not identified using the CDC reference. Using ethnic-specific references or ethnic-specific cut-points may help improve overweight identification for Chinese American children.