What are these statistics?
The intention of this release is to provide statistics on mothers and babies, throughout the maternity and birth process. The release supports the Welsh Government maternity vision: Maternity Care in Wales, A Five Year Vision for the Future (2019-2024), published in July 2019.
A number of statistics and analyses are produced on key areas including:
- how far into pregnancy a woman receives her initial assessment (or booking appointment)
- how many mothers are smokers
- how many mothers are overweight
- whether the mother intends to breastfeed, and actual breast feeding rates at birth, 10 days, 6 weeks and 6 months
- the mode of onset of labour, whether pain relief was administered and the mode of birth including planned and emergency Caesarean sections
- number of live births in Wales
- low birthweight rates
Sources of data
These statistics are derived from two data sources: the Maternity Indicators dataset (MI ds) and the National Community Child Health Database (NCCHD). Both data sources are provided to the Welsh Government by Digital Health and Care Wales.
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. In merging initial assessment data with birth record data, NWIS take the following validation steps:
- initial assessment and birth records where the mother’s NHS number is missing are removed
- birth records where the baby has no NHS number are removed, all other birth records are retained
- data from the initial assessment is merged with the birth record using the mother’s NHS number, which should be a unique identifier on both records
- records where the health board providing the initial assessment and where the birth occurred are the same, are retained, all other initial assessment data are removed
- where the birth record could not be matched to an initial assessment record, the birth record is still retained and all initial assessment data will be missing
- records where the number of days between the initial assessment and date of birth is between -1 and 315 are retained
- where there are still multiple initial assessment records for a birth, checks are performed to establish the most complete merged record; that record is then retained and any remaining duplicates are removed
This complex process results in many records being removed from the dataset, therefore there are limitations in the use of statistics produced from the Maternity Indicators dataset.
The National Community Child Health Database was established in 2004 and consists of anonymised records for all children born, resident or treated in Wales and born after 1987. The database brings together data from local Community Child Health System databases which are held by local health boards (LHBs) and its main function is to provide an online record of a child’s health and care from birth to leaving school age. The statistics used in this release are based on the data recorded at birth and shortly after birth.
Local Child Health Systems change over time to meet changing requirements; the latest and fourth version is known as the Children and Young Persons Integrated System (CYPrIS), and is being rolled out to all health boards during 2019. More information on its features is available on the NWIS website.
Full details of every data item available on both the Maternity Indicators dataset and National Community Child Health Database are available through the NWIS Data Dictionary.
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. It does not include any births for Welsh resident mothers who gave birth in England or in any other country outside of Wales.
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 National Community Child Health Database includes records of all children born in, resident in or receiving services in their relevant local health boards. This means the database contains some information for some children not currently residing in Wales; however, unless otherwise stated, all statistics produced from data sourced from this database is filtered to only include those children born in Wales. It also means that data is available for Welsh resident mothers who gave birth in England.
Data on breastfeeding at birth, 10 days, 6 weeks and 6 months refers to the time period in which the activity occurred, rather than when the child was born.
The National Community Child Health Database records both live and stillbirths, however the majority of analysis in the statistical release refers only to live births.
Analysing data from the National Community Child Health Database provides additional information on new-born children which is not available through the Office for National Statistics’ (ONS) official measure on the number of births. Data from both sources is very closely aligned, but the Office for National Statistics’ measures allow for more accurate comparisons between UK countries.
Published statistics on maternity and births in Wales
Maternity and birth statistics were first published as a single statistical release in October 2019 with new data referring to calendar year 2018. Previously these statistics were published in two separate statistical releases.
A number of other statistics are published using data sourced from the National Community Child Health Database:
- annual statistical release and quarterly StatsWales updates on the Healthy Child Wales Programme
- quarterly statistics on breastfeeding
- annual statistics on immunisations
The National Maternity and Perinatal Audit (NMPA) publish reports on topics such as neonatal mortality and breastfeeding in neonatal units which includes data for Wales.
Birth data from National Community Child Health Database is also published on Health Maps Wales.
What are the potential uses of these statistics?
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
Who are the key potential users of this data?
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
If you are a user and do not feel the above list adequately covers you, or if you would like to be added to our circulation list, please let us know by e-mailing email@example.com.
Strengths and limitations of the data
Strengths: in general for both data sources
- Data collected is used operationally by health boards so there is no additional burden on data suppliers and there are not any survey sampling issues.
- There are a wide range of data items available, allowing for a broad overview of maternity and birth statistics for mothers receiving services in Wales.
- Data is collected on a broadly consistent basis across Wales, though there are some differences in health board systems and methods of recording data.
- The key statistics from both sources largely meet the needs of users and support Welsh Government in making evidence based polices. The majority of data is available through these sources to monitor key performance indicators which the Welsh Government sets for local health boards.
- Statistics are published regularly and as timely as possible, with additional tables published on StatsWales.
- The number of births recorded in hospitals is very closely aligned between both the Maternity Indicators dataset and National Community Child Health Database.
Strengths: maternity indicators dataset
- The merging of the initial assessment and birth records allow us to analyse data across the whole maternity and birth process. It allows for monitoring areas of interest such as smoking during pregnancy and bespoke analysis can be performed such as analysing birth outcomes when the mother is overweight.
- The data is an administrative source which has a reasonable level of completeness across most data items, across all health boards (completeness tables shown at Table 2).
Strengths: National Community Child Health Database
- The dataset has long been established, is processed efficiently by NWIS, and aligns very closely with ONS’ measure on the number of births in Wales
- Data allows for more detailed analysis of birth in Wales than are provided by the ONS births measures.
- The data is an administrative source which has a high level of completeness across most data items, across all health boards (completeness tables shown at Table 3).
Limitations: in general for both data sources
- The StatsWales information is intended for a more informed audience, without full explanatory notes.
- As data is typically inputted into the computer system manually in the health boards, there is a risk of human processing errors.
- The Maternity Indicators dataset does not record information on births which occur outside of country to Welsh resident mothers, but the National Community Child Health Database does. The number of home births recorded in the Maternity Indicators dataset is lower than the number recorded in the National Community Child Health Database. The differences in these two recording practices largely explain the differences in the number of births in each dataset.
Limitations: maternity indicators dataset
The Maternity Indicators dataset is a complex dataset, which is subject to extensive validation processes. There are a number of limitations in the statistics produced from this data source and as a result, all statistics from this source are classed as experimental statistics. Some of the limitations include:
- Initial assessment data is only included for records where the initial assessment and birth took place in the same health board. This creates two significant limitations:
- Initial assessment records where the initial assessment takes place in a different health board to the birth are removed in the merging process and are not accounted for in any of the analysis.
- If a mother has an initial assessment in one health board, and gives birth in a different health board but her information from the initial assessment is not transferred, a second ‘initial assessment’ may occur in the health board where the birth occurs. This means that this record will be included in the Maternity Indicators dataset, but the information for the initial assessment will come from the second assessment, and is likely to be significantly different for a number of data items, like BMI and gestational age at initial assessment. These records are retained as we are unable to confidently differentiate between these cases and mothers who genuinely have their first assessment close to birth.
- While data completeness is relatively good for most data items, it can be mixed for some data items, particularly when assessing coverage at health board level. This means changes over time should always be assessed with their data completeness in all years, as any perceived changes may be due to changes in data coverage rather than actual changes in the trend.
- Data validation rules for health boards are not entirely consistent; some data items contain values which are not valid according to the data dictionary.
- Some health boards record data items inconsistently; for example, some health boards record ‘no previous Caesareans’ as 0 while others record it as 99.
- Values for some raw data items are obviously incorrect; for example, thousands of records have unrealistic values for mother’s heights and weights which need to be removed from the published statistics. This raises questions around the general reliability of data recording across all data items.
- The analysis on smoking during pregnancy is limited because CO (Carbon Monoxide) testing is not available for all assessments across all health boards, so some data is included on the mother self-reporting their smoking status. In addition, CO monitoring will not capture mothers who use e-cigarettes, but some health board may record a mother self-reporting as an e-cigarette user as a smoker, so there may be inconsistencies in the recording of this data item.
- Births outside of hospitals (usually at home) are sometimes, but not always recorded in the database,and the way the data is recorded does not always allow us to identify in which setting the birth occurred.
- The Maternity Care in Wales strategy requires the monitoring of a range of data fields which are not currently included in the Maternity Indicators dataset.
Limitations: National Community Child Health Database
There are few limitations in using data from the National Community Child Health Database, though some potential limitations include:
- While the number of births closely aligns to the ONS measure, there are sometimes very small differences so the two sources are not always 100% coherent.
- While data completeness for most data items is very high, they might not always be 100% complete so there may be a small amount of missing data.
- Data on ethnic group is much less complete than most other data items in the database.
- Data from the database is not currently linked to the Maternity Indicators dataset; if it was then there would be potential to extend analysis to assess the relationship between events which happen in pregnancy with outcomes for the child after birth and in their early years. For example, analysis could be produced on the relationship between the timing of the initial assessment and breastfeeding rates.
- Other statistical releases using data from the database are not currently linked to the maternity and births statistical release, these include statistics on the Healthy Child Wales Programme.
Both Maternity Indicators dataset and National Community Child Health Database data items are listed in the NHS Wales Data Dictionary.
Data processing cycle
The broad data processing steps for the Maternity Indicators dataset is as follows:
- initial assessment and birth data are recorded by health boards on their own systems
- NHS Wales Informatics Service (NWIS) ‘pull’ data from health boards, once a month
- NWIS inform health boards that data extracted in April, will be used in Official Statistics for the previous calendar year, allowing health boards time to ensure their data is as complete as possible by this date
- NWIS stores the data on temporary databases before merging the two datasets
- records are merged by using a combination of the mother’s NHS Number and the date of initial assessment from both temporary datasets
- NWIS perform additional validation on the data and then send to the Welsh Government a pseudonymised data extract in May
A similar data processing cycle exists for the National Community Child Health Database:
- health boards enter data onto their own child health systems
- NWIS extract data every quarter and store in their own database
- a grouping process is then applied to the database using valid anonymised NHS numbers so that records relating to the same child can be identified
- the National Community Child Health Database is built from this data with the aim of obtaining maximum record completeness
- the extract taken in April is used for births occurring in the previous calendar year and a pseudonymised version is sent to Welsh Government for use in this statistical release
Once data is received by Welsh Government, a range of data validation checks are performed, these include:
- identifying duplicate records
- deriving the number of babies born from each pregnancy
- identifying incorrect data for mother heights and weights and recalculating BMI
- recoding invalid data values to the value for ‘not stated’
- recoding blank fields to the value for ‘not stated’
- standard sense checks against previous years’ data
- checking that data items for certain fields are consistent between records where there was a multiple births (i.e. twins or triplets)
Disclosure and confidentiality
The data which Welsh Government receives for both datasets contains individual but anonymised records. This means that no person (mother or baby) are identifiable in either dataset.
NWIS take several steps to protect personal information before sharing it, and Welsh Government take disclosure control steps before publishing data, these include:
- creating pseudoynmised ID’s for mothers and babies which are unique identifiers, based on NHS numbers, which cannot be traced back to the actual NHS number by anyone who sees the Welsh Government data extract
- names and dates of birth are not included in either dataset
- Welsh Government publishes statistics at aggregated levels
- any counts under 3 for any specific data item are supressed before publication
Data is submitted on Excel spreadsheets via Afon, the Welsh Government secure web data transfer system or secure email. Data is stored and analysed using an Access databases.
Welsh Government statistics are published in line with our statement on confidentiality and data access which is informed by the trustworthiness pillar contained in the Code of Practice for Statistics.
This is published in detail at the back of the statistical release.
Statistics published by Welsh Government adhere to the Statistical Quality Management Strategy which supplements the Quality pillar of the Code of Practice for Statistics and the European Statistical System principles of quality for statistical outputs. This statistical release aims to meet these quality principles in the following ways.
Principle 11: Relevance
The statistics provide an overview of maternity services and birth characteristics in Wales. The statistics support the Welsh Government maternity vision: Maternity Care in Wales, A Five Year Vision for the Future (2019-2024).
Statistics also support analysis of key public health topics like breastfeeding and smoking and obesity in pregnancy.
Background information about statistics and sources is published for users and encourage users of the statistics to contact us to let us know how they use the data.
We consult with key users prior to making changes, and where possible publicise changes on the internet, at committees and other networks to consult with users more widely. We aim to respond quickly to policy changes to ensure our statistics remain relevant.
Principle 12: Accuracy and Reliability
The Maternity Indicators dataset is recently established and data quality is mixed. Welsh Government and NWIS are working with health boards to improve completeness and quality. In comparison with other sources of births and maternity data, overall counts and key statistics align reasonably well, given the limitations created by the complex merging process.
There are however specific issues with a few of the data items where the data provided does not wholly align with the Data Dictionary specification and where some health boards have difficulties providing the required data. Only a selection of the available data items has been included in this statistical release but as the data quality improves we hope to expand its scope and depth.
A comparison of the total number of records per year is shown in Table 1. Table 2 and Table 3 show how complete individual data items are across both sources. Accompanying tables
Note that data from the Maternity Indicators dataset only includes data on mothers and babies where the initial assessment and birth occurred in the same health board.
Data from the National Community Child Health Database includes data on children born to Welsh residents and on children born in Welsh hospitals to non-Welsh residents. Statistics in this release are generally filtered on those children born in Wales to Welsh residents.
The charts and tables in the statistics may include categories for not stated data. Calculated percentages exclude not stated values from the denominator unless otherwise stated. The quantity of missing data for each data item is referred to throughout the text.
Both Maternity Indicator dataset and National Community Child Health Database are live databases, meaning health boards can amend data for any period. For the statistics in this release, NWIS 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. In the case of incorrect data being published, revisions would be made and users informed in conjunction with our Revisions, errors and postponements policy.
Note that in 2019, new data from the Maternity Indicators dataset was published for calendar years 2016, 2017 and 2018. Previous maternity statistics publications were experimental statistics, based on financial years. Publishing on a calendar year basis required new Maternity Indicators data extracts to be produced by NWIS for the full time series, therefore data and trends published in previous publications may have changed.
Principle 13: Timeless and Punctuality
Data is published as soon as is practicable.
The data provider (NWIS) extracted both datasets in April 2019, for the reference year 2018. This allows some tolerance for health board’s late recording of maternity and birth information. Health boards are informed when data will be extracted and they endeavour to keep information accurate at this point in time.
Data for calendar year 2018 is currently published in the autumn 2019; this allows the necessary time to perform validation checks on both datasets before publishing.
Publication dates are announced well in advance and any delays are communicated via notices on our website. Any revisions or postponements to outputs follow the Revisions, errors and postponements policies.
Principle 14: Coherence and Comparability
Data from the Maternity Indicators dataset 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.
Information is provided on why the number of births between sources is different. Comparisons of births between different parts of the UK should be made using ONS data which is collected on a comparable basis.
Maternity and birth statistics for other UK countries is available.
Scotland: Births in Scottish Hospitals
Northern Ireland: Birth Statistics
England: NHS Maternity Statistics
Principle 15: Accessibility
The statistics are published in an accessible, orderly, pre-announced manner on the Welsh Government website at 9:30am on the day of publication. An RSS feed alerts registered users to this publication. Simultaneously the releases are also published on the National Statistics Publication Hub.
Statistical releases are publicised on Twitter and all releases are available to download for free.
Alt text is provided for all charts so that they can be read with a screen-reader.
Data from NCCHD is published on StatsWales and data from MI ds will be added in due course. This allows users to download and link data in an open data format.
The statistical release in 2019 combines two previous statistical releases on maternity and birth statistics and aims to improve on data clarity to users, providing clearer messages about the strengths and limitations of data sources and puts all statistics on maternity and births in one place.
All our webpage headlines are published in Welsh and English.
The United Kingdom Statistics Authority designates statistics as National Statistics in accordance with the Statistics and Registration Service Act 2007 and compliance with the Code of Practice for Statistics. The statistics in this release are Official Statistics, but as they have not been through the badging process, they are not National Statistics. All statistics which are produced from the Maternity Indicators dataset are also classed as experimental statistics.
Given the strengths and limitations listed above, data from both the Maternity Indicators dataset and National Community Child Health Database are of sufficient quality to justify publication. An extensive statistical release is published with high level summaries and charts, with interactive data tables are published on StatsWales.