# Do Anthropometric Health Risk Indicators of South African Primary School Children Require National Growth Charts? Insights from the NW-CHILD Study

## TL;DR

South African primary school children's growth patterns differ by age, gender, and socioeconomic status, suggesting the need for national growth charts to better assess health risks.

## Contribution

The study identifies the need for national growth charts in South Africa that account for age, gender, and socioeconomic status, beyond existing global standards.

## Key findings

- Age, gender, and socioeconomic status significantly influence anthropometric indicators like BMI and waist circumference in South African children.
- Children from high socioeconomic status groups trend above WHO standards, while low SES children align closely with them.
- National growth references incorporating age, gender, and SES are needed for more accurate health risk screening.

## Abstract

What are the main findings?
Age, gender, and socioeconomic status (SES) significantly influence height, body mass index (BMI), waist circumference, and skeletal muscle in South African primary school children.South African children from low SES aligned closely with World Health Organization (WHO) standards at the 50th percentile, whereas children from high SES trend above these expected standards.

Age, gender, and socioeconomic status (SES) significantly influence height, body mass index (BMI), waist circumference, and skeletal muscle in South African primary school children.

South African children from low SES aligned closely with World Health Organization (WHO) standards at the 50th percentile, whereas children from high SES trend above these expected standards.

What are the implications of the main findings?
Anthropometric cut-points are needed that extend beyond height, weight, and BMI for primary school children in South Africa (SA), incorporating the influence of age, gender, and SES.Nationally developed growth references taking into account age, gender, and SES are needed to timeously and comprehensively screen for health risks in South African primary school children.

Anthropometric cut-points are needed that extend beyond height, weight, and BMI for primary school children in South Africa (SA), incorporating the influence of age, gender, and SES.

Nationally developed growth references taking into account age, gender, and SES are needed to timeously and comprehensively screen for health risks in South African primary school children.

Background/Objectives: Growth monitoring and screening are vital indicators for child wellness. Controversy exists regarding the use of national versus international growth charts for school-going children. This study investigated the suitability of existing global references, considering the influence of age, gender, and socioeconomic status (SES), and the specific growth patterns across multiple anthropometric health indicators (AHIs). Methods: A total of 349 children (boys = 165, girls = 184, low SES = 201, high SES = 148) were measured longitudinally at ages 6, 9, and 12 years while attending primary school. AHI included stature, body mass, body mass index (BMI), body fat percentage (BFP), skinfold thickness, skeletal muscle, and waist circumference (WC). Results: Three-way interaction effects were found for age, gender, and SES on WC and skeletal muscle (p = 0.05). Several two-way interactions emerged for age and gender (height, BMI, skeletal muscle; p < 0.01), as well as age and SES (height, BMI, skeletal muscle; p < 0.01) and gender and SES (height, skeletal muscle, WC, p < 0.05). Cut-points for height, body mass, and BMI at the median, compared to universal standards, indicate that the total group fell at, or slightly above, World Health Organization (WHO) standards. The low SES group aligned with WHO standards, whereas the high SES group trended above the reference values at most points. Conclusions: The WHO growth standards are suitable for general monitoring in South African children aged 6–12 years but provide limited context-specific interpretation across age, gender, and socioeconomic backgrounds. National age-, gender-, and SES-specific growth references, incorporating additional anthropometric indicators, are needed to support locally relevant screening.