Official Statistics

NCMP data for the 2020 to 2021 academic year by upper tier local authority: short statistical commentary

Published 20 January 2022

Applies to England

This publication presents analyses of National Child Measurement Programme (NCMP) data collected in the 2020 to 2021 school year by upper-tier local authority of child residence and upper-tier local authority of school for children in Reception (age 4 to 5) and Year 6 (age 10 to 11). It shows prevalence of underweight, healthy weight, overweight, obesity, severe obesity and overweight and obesity combined. It is the first publication of NCMP data at local authority level since the COVID-19 pandemic.

Data is included for 25 out of the 152 upper-tier local authorities in England where 75% or more child measurements were submitted compared to previous full measurement years (2016/2017 to 2018/2019). Therefore, the data cannot be used to assess which areas have the highest or lowest prevalence across the country as data is not available for all local authorities. Data for the local authorities in this publication can be compared to previous years of NCMP data.

1. NCMP 2020 to 2021 data collection year

The start of the 2020 to 2021 NCMP was delayed as schools were closed due to the COVID-19 pandemic. In March 2021 local authorities were asked to collect a representative 10% sample of data because it was not feasible to expect a full NCMP collection so late into the academic year. This representative sample would enable a national estimate of children’s weight status (including obesity prevalence) for 2020 to 2021 and contribute towards assessing the impact of the COVID-19 pandemic on children’s physical health.

The 2020 to 2021 NCMP collection achieved much more than requested; around 25% of a usual full measurement year. Some local authorities were able to collect more than the requested 10% sample; 18 upper-tier local authorities were able to collect data for 75% or more Reception children compared to previous years, and 19 upper-tier local authorities were able to collect data for 75% or more Year 6 children.

2. Interpreting the local authority data

As the national level estimates published by NHS Digital were only based on around 25% of the normal number of measurements, the data was weighted to make the estimates representative of the cohort of children seen in previous years. However, it has not been necessary to weight the data used for these 25 local authorities as they all measured at least 75% of children compared to a full measurement year.

The sampling approach was developed to estimate prevalence at a national level and was not specifically designed for local authority level prevalence calculations. In general, the greater the number of measurements used within any analysis, the more reliable the resulting statistics. Therefore, a minimum of 75% child measurements submitted compared to previous full measurement years is recommended to produce robust estimates of obesity prevalence at local authority level. This is consistent with the approach NHS Digital took for the 2019 to 2020 NCMP report when local authorities meeting this threshold had their results published without any data-quality caveats.

When interpreting data, it is important to consider the confidence intervals (CI) for the values as they show the level of uncertainty in the prevalence estimates. Confidence intervals (CI) are provided in the spreadsheet titled ‘Lower CI’ and ‘Upper CI’.

Prevalence of child obesity and excess weight varies across England. Analysis of national data shows that children in the most deprived areas in England are at the highest risk of living with overweight and obesity. This should be considered when interpreting the data.

3. Further information about this publication and the data used

In a normal year, the NCMP measures the height and weight of over one million children in England and provides robust data on rates of child obesity and excess weight.

Further information on methods used is available in the notes section of the spreadsheet.

Children with a body mass index (BMI) equal to or less than the 2nd centile of the British 1990 growth reference (UK90) BMI distribution have been classified as underweight.

Children with a BMI greater than the 2nd centile and less than the 85th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as healthy weight.

Children with a BMI greater than or equal to the 85th centile and less than the 95th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as overweight.

Children with a BMI greater than or equal to the 95th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as obese.

Children with a BMI greater than or equal to the 85th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as overweight including obese (excess weight).

Children with a BMI greater than or equal to the 99.6th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as severely obese (note: ‘severely obese’ is a subset of ‘obese’).

Previously published NCMP data for these local authorities can be found and examined in the Office for Health Improvement and Disparities (OHID) Obesity Profile.

The statistics were produced using the national analysis dataset provided to OHID by NHS Digital.

Responsible statisticians, product leads: Caroline Hancock and Catherine Bray

For queries relating to this document, please contact: ncmp@phe.gov.uk