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Welsh Government
Data Provider: Welsh Government BMI at initial assessment, by ethnic group
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Year[Filtered]
Measure[Filtered]
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BMI Group[Filter]
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Ethnic group 1
Click here to sortBMI 10 < 18.5Click here to sortBMI 18.5 < 25Click here to sortBMI 25 < 30Click here to sortBMI 30+Click here to sortNot statedClick here to sortTotal womenOnly includes mothers whose initial assessment was completed at 14 completed weeks of pregnancy or earlier.
[Collapse]All ethnic groups2024 Wales data excludes data from Aneurin Bevan because of the low reliability of the data. See notes.3796,1284,9385,40993117,785
All ethnic groups2024 Wales data excludes data from Aneurin Bevan because of the low reliability of the data. See notes.WhiteAny white background2564,1543,2923,77855412,034
Mixed/MultipleWhite and Asian, white and black African, white and black Caribbean, any other mixed background11107931006317
AsianPakistani, Bangladeshi, Chinese, Indian, any other Asian background3838630416130919
BlackAfrican, Caribbean, any other black background1013115014312446
Other1117906412284
Not stated631,2331,0091,1633173,785

Metadata

Title

BMI at initial assessment, by ethnic group

Last update

August 2025 August 2025

Next update

July 2026 (provisional)

Publishing organisation

Welsh Government

Source 1

Maternity Indicators data set

Contact email

stats.healthinfo@gov.wales

Lowest level of geographical disaggregation

Wales

Geographical coverage

Wales

Languages covered

English and Welsh

Data licensing

You may use and re-use this data free of charge in any format or medium, under the terms of the Open Government License - see http://www.nationalarchives.gov.uk/doc/open-government-licence

General description

This data is derived from the Maternity Indicators dataset which is provided to the Welsh Government by Digital Health and Care Wales (DHCW).
The Maternity Indicators dataset was established in 2016. It combines records from a mother’s initial assessment with a child’s birth record and enabled Welsh Government to monitor its initial set of outcome indicators and performance measures (Maternity Indicators) which were established to measure the effectiveness and quality of Welsh maternity services.
The Maternity Indicators dataset allows us to analyse characteristics of the mother’s pregnancy and birth process. The process for producing this data extract is complex largely because there can be multiple initial assessment data and records for both initial assessments and births are not always complete.
Full details of every data item available in the Maternity Indicators dataset are available through the NHS Wales Data Dictionary: http://www.datadictionary.wales.nhs.uk/#!WordDocuments/datasetstructure20.htm

The data dictionary also defines how ethnic groups are classified, namely: White (any white background); Asian (Pakistani, Bangladeshi, Chinese, Indian, any other Asian background); Mixed/multiple (white and Asian, white and black African, white and black Caribbean, any other mixed background); Other (any other ethnic group); Black (African, Caribbean, any other black background).

Data collection and calculation

Data from the Maternity Indicators dataset only includes initial assessment data where the initial assessment and birth both occurred in the same health board, in Wales only.
Data should include all hospital births and some home births; however, due to the way data is recorded, we are unable to distinguish between home and hospital births in some health boards. Births to Welsh resident mothers who gave birth in England or in any other country outside of Wales are not included in the data.
Data for each calendar year refers to when the baby was born for both birth and initial assessment statistics. Initial assessments may have taken place in the previous year but would be counted in the year in which the birth occurred. This ensures data throughout a single pregnancy is recorded in the same year.

The Wales-level percentage for pregnant women with BMI of 30 or greater are based on all records minus records with a ‘not stated’ or invalid value. Records where BMI, height or weight are unrealistic values are classed as invalid, for example where BMI is less than 10 or greater than 100; where the pregnant woman’s weight is less than 30kg or more than 250kg; and where the pregnant woman’s height was less than 120cm or greater than 200cm. The number of records excluded can be found in Table 4 of the Maternity and birth statistics: quality report tables (https://www.gov.wales/maternity-and-birth-statistics-quality-report)
The calculation also only includes women who had their initial assessment at 14 completed weeks of pregnancy or earlier. This is to reduce unfair comparisons where the BMI calculation is affected by baby growth where the initial assessment happened after 15 weeks. Between 11% to 15% of all pregnancies have been excluded for this reason in each year.

Frequency of publication

Annual

Data reference periods

2016 to 2024

Users, uses and context

These statistics will be used in a variety of ways. Some examples of these are:
• advice to Ministers
• to inform debate in the Welsh Parliament and beyond
• to make publicly available data on child health statistics in Wales
• monitoring service delivery
• policy development
• providing advice on birth choices
The main users are:
• Ministers, policy officials and the Members Research Service
• local health boards
• the public
• the research community
• students, academics and universities
• Public Health Wales and other NHS organisations
• voluntary birth organisations.

Rounding applied

No rounding applied

Revisions information

The Maternity Indicators dataset is a live database, meaning health boards can amend data for any period. For this data, DHCW take data extracts from a single point in time, for the latest calendar year. This means that if data extracts are taken for previous time periods, they may differ to the data which is published as it may have been revised by health boards. Welsh Government will not make revisions to historical data unless errors are discovered.

Statistical quality

From 1st April 2019 health service provision for residents of Bridgend local authority moved from Abertawe Bro Morgannwg to Cwm Taf. For more information see the joint statement from Cwm Taf and Abertawe Bro Morgannwg University Health Boards (see weblinks). The health board names have changed with Cwm Taf University Health Board becoming Cwm Taf Morgannwg University Health Board and Abertawe Bro Morgannwg University Health Board becoming Swansea Bay University Health Board.
Data for Abertawe Bro Morgannwg and Cwm Taf are available for previous years in this table by selecting the tick boxes in the Area drop-down box.
More detailed information on the sources of data and analyses in this statistical release are provided in the quality report: https://www.gov.wales/maternity-and-birth-statistics-quality-report

More than 90% of records had valid data for both height and weight data items, across all health boards, in most years apart from: Cwm Taf in 2016 (77%) and in 2019 (88%); and Betsi Cadwaladr in 2019 (89%).
In 2024, Aneurin Bevan has been excluded from analysis due to high levels of invalid data for height leading to 77% missing data for BMI. Data for Wales represents the 6 remaining health boards.

Keywords

maternity; initial assessment; BMI; Body mass Index; ethnic group