Smoking status of women at initial assessment and at birth by local health board

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Next update expected:August 2026

Updates

4th August 2026

This update includes the latest annual data and revisions to the previous annual data. All revisions are marked with the [r] note code.

7th January 2026
Dataset first published.

Main information

Designation
Accredited official statistics
Data provider
Digital Health and Care Wales (DHCW)
Data source
Maternity Indicators Dataset (MIDS)
Time period covered
January 2016 to December 2025
Dataset ID
d6786da1-1b3b-4f96-9da9-ffedfdaa9181

Overview

Summary of dataset and variables

Number and percentage of women who smoked at initial maternity assessment and at birth broken down by local health board.

This data is derived from the Maternity Indicators dataset, provided to the Welsh Government by Digital Health and Care Wales (DHCW).

The Maternity Indicators dataset combines records from a mother’s initial assessment with a child’s birth record.

Full details of every data item available in the Maternity Indicators dataset are available through the NHS Wales Data Dictionary.

Data collection or 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.

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. Initial assessments may have taken place in the previous year but would be counted in the year in which the birth occurred.

Smoking at initial assessment: While there is a high percentage of valid data for smoking status at initial assessment, reliability depends on self-reporting when CO monitoring is unavailable. CO monitoring was largely suspended during the COVID-19 (2020 to 2023) , so most data in this period is self-reported.

CO monitoring rates:

  • Pre-2020: 20–30%
  • 2021–2022: 1–2%
  • 2025: 26% (near pre-pandemic levels)

E-cigarette use is not detected by CO monitoring and should not be recorded, but some mothers may self-report inaccurately.

Percentages are based on records with valid smoking data; missing data counts are in the quality report.

Smoking at birth: Data faces similar limitations as initial assessment, with increasing missing/invalid records in recent years. At birth, CO monitoring was lower than at initial assessment:

  • 2016–2020: 1–3%
  • 2025: 9%

The number of records with no stated smoking status at birth can be found in Table 4 of the Maternity and birth statistics quality report tables.

Statistical quality

Smoking at initial assessment: Due to data quality issues with the smoking at birth data, smoking at initial assessment for Swansea Bay and Hywel Dda has been excluded from 2021 to 2023 for compatibility purposes.

Smoking at birth: Swansea Bay was not included in the Wales totals from 2021 to 2024 and Hywel Dda was not included in the Wales totals from 2021 to 2023.

In 2024, data for Wales was from the remaining 6 health boards and from 2021 to 2023 was from the 5 remaining health boards. Swansea Bay was excluded from the smoking at birth data due to data quality concerns and Hywel Dda was excluded as they did not provide any data for smoking at birth between 2021 and 2022 and provided incomplete data in 2023. This resulted in excluding smoking at initial assessment for Swansea Bay and Hywel Dda for these time points for compatibility purposes. In 2021 and 2022 Cwm Taf Morgannwg had an unusually high percentage of missing data.

The number of records with missing data has varied throughout the time series and has increased in recent years. The number of missing records can be found in Table 4 of the Maternity and birth statistics quality report tables.

From 1st April 2019 health service provision for residents of Bridgend local authority moved from Abertawe Bro Morgannwg to Cwm Taf. The health board names changed to Cwm Taf Morgannwg University Health Board and Swansea Bay University Health Board. Data for Abertawe Bro Morgannwg and Cwm Taf are available for previous years in this table. More detailed information on the sources of data and analyses in this statistical release are provided in the quality report.

Related reports

Published by

Organisation
Welsh Government
Contact email
stats.healthinfo@gov.wales