NHS Digital Data Release Register - reformatted

City University Of London projects

Linkage, analysis and dissemination of national birth and maternity data for England and Wales

5 data files in total were disseminated unsafely (information about files used safely is missing for TRE/"system access" projects).

Linkage, analysis and dissemination of national birth and maternity data for England and Wales — DARS-NIC-10094-P6P4B

Type of data: information not disclosed for TRE projects

Opt outs honoured: Identifiable (Section 251 NHS Act 2006)

Legal basis: Health and Social Care Act 2012 s261(7); National Health Service Act 2006 - s251 - 'Control of patient information'., Health and Social Care Act 2012 - s261(5)(d); National Health Service Act 2006 - s251 - 'Control of patient information'.

Purposes: No (Academic)

Sensitive: Non-Sensitive

When:DSA runs 2019-08-16 — 2022-08-15

Access method: One-Off

Data-controller type: CITY UNIVERSITY OF LONDON, CITY, UNIVERSITY OF LONDON

Sublicensing allowed: No

Datasets:

Hospital Episode Statistics Admitted Patient Care
Hospital Episode Statistics Admitted Patient Care (HES APC)

Objectives:

City, University of London requires continuing access to previously provided HES data. These data were provided for the purpose of maintaining a research database which can potentially be accessed by authorised researchers using the secure environment of the Office for National Statistics, ONS Secure Research Service (SRS), formerly known as the Virtual Microdata Laboratory (VML), subject to obtaining the required ethics and section 251 approvals. Permission for this was given explicitly in CAG-08(b)/2014 which also covered planned analyses. No new data are requested in this agreement. It includes the same analyses as the previous agreement. It was not possible to complete these during the funding period for the previous project, because of delays in data access, so further funding has been obtained to continue the work.

All the data provided to the project had already been collected through the processes of civil registration, birth notification, compiling the Hospital Episode Statistics or perinatal audit by the now disbanded Centre for Maternal and Child Enquiries. There was no primary data collection. In selecting variables for linking and analysis, every attempt was made to strike a balance between the need to request the key data items needed for analysis and requesting data items which were crucial to enabling the linked dataset to be used by other researchers. At a later stage in the series of projects, it was necessary to request a few further data items in order to do the linkage and answer the research questions.

The database was created as a result of three collaborative projects led by City, University of London over a period of more than ten years the first of these funded by City University RAE Development Fund involved pilot linkage of birth registration records to birth notification records, previously known as the NHS Numbers for Babies (NN4B) records. Birth registration records were already linked by the Office for National Statistics (ONS) to death registration records for babies who died. The pilot was successful and ONS mainstreamed the linkage for the years 2006 onwards. Since then, the linked records have been used for publications and research and the data have been provided already being for further linkage to other.

In the second project, funded by the MRC, the already linked birth registration and notification data were further linked to HES Maternity delivery and birth records and permission was given to hold these as a database. This database adds value to the HES data by adding further data items from birth registration and notification and more complete data for important data items, notably birthweight and gestational age where HES are incomplete. It was created to enable analyses relating to inequalities in the outcome of pregnancy and information for service users about the outcome of midwifery, obstetric and neonatal and related health care.

As part of the third project, -Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for the NHS, funded by NIHR, there was further linkage of birth and delivery records to admitted patient care records relating to any subsequent admissions of these mothers and children to hospital and a relational database was constructed to hold the linked records. Funding has been secured from ESRC for a follow on project, Implications of time of day and day f week for the outcome of birth which will use the same data to do some of the uncompleted analyses from the third project.

These are justified under Article 9.2(j) of the General Data Protection Regulation as being of substantial public health interest and scientific purposes as evidenced by consultations held with service users as part of the research and in the extent of media coverage when the analyses have been published.

Under this Data Sharing Agreement, use of the data is approved for two projects led by City, University of London. These are the original third project, entitled Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for the NHS and the follow-on project, Implications of time of day and day of the week for the outcome of birth. This follow-on project is made up of analyses which were approved as part of the earlier project, but remained uncompleted at the end of the funding period. The database was originally established in its current form as part of the project, extending and updating work done in preceding data linkage projects.

Taken as a whole these analyses were designed to be undertaken in the public interest under Article 6(1)(e) of the General Data Protection Regulation in response to concern about the possibility of hourly and daily differences in the quality and safety of maternity and related care. Analyses since the 1970s have shown that maternity outcomes have apparently differed by day of the year, day of the week and time of day. The project aimed to understand the reasons for this. Public and patient involvement is a key part of this work and consultations with service users showed considerable interest and support along with confidence that individuals were not going to be identified in a database of over seven million births held in a secure setting.

City, University of London is the Data Controller and responsible for managing access to this database and the purpose(s) for which the data may be used. It has the necessary ethics and Section 251 approvals for establishing and maintaining the database. City, University of London may only grant access to the research database which City University of London have produced to researchers who have the necessary ethics and Section 251 approvals for purposes approved by NHS Digital. It will ensure that data access is restricted to ONS personnel - defined as all employees, agents and contractors of the Data Recipient who may have access to the Data or to personnel employed by an organisation named as a Data Processor in an active Data Sharing Agreement for the purposes defined in that Agreement.

This Data Sharing Agreement covers only the data supplied by NHS Digital; not the ONS data to which it is linked.

The aims of the project were to compare daily, weekly and yearly variations in numbers of spontaneous and other births by time, day and season of birth and to compare variations in rates of adverse outcome. The project aimed to answer the following questions:

1. How do numbers of births vary according to time of day, day of the week and time of year of birth and how does this relate to methods of onset of labour and delivery and multiplicity?

2. Subject to the availability of data, how do patterns of birth vary between maternity services in relation to variations in medical and midwifery staffing, patterns of intervention and size of unit?

3. How does the outcome of pregnancy in terms of rates of cause specific intra-partum stillbirth and neonatal and infant mortality rates and rates of morbidity recorded at birth and at hospital admission in the first year of life vary according to time of day, day of the week and time of year in relation to gestational age, and intervention in the onset of labour and delivery?

4. Have the patterns observed changed over the years 2005 onwards?

The project aimed to inform decision-making by providing information about how numbers of births in England and Wales vary by time of day, day of week and day of the year.

It analysed separately births before term and those after full term pregnancies. In addition it is took account of whether labour and delivery occurred spontaneously or whether their timing was affected by inducing labour, or by undertaking either a planned caesarean section or an emergency caesarean section during labour.

It produced answers to questions 1 and 4 but because of delays in data access, there was not time to answer questions 2 and 3 under the previous agreement within the time period funded by NIHR. Further funding has now been secured from the ESRC and this new agreement will make it possible to answer outstanding questions. In particular, the rates of death and severe problems in babies or their mothers will be analysed in relation to the factors outlined above. This is a question of considerable public concern.

The results will be related to maternity units and NHS trusts overall rates of induction and caesarean section. As far is feasible within the limitations of data quality and completeness, it will draw on available information about their overall rates of midwifery and obstetric staffing although work done to date suggests that the extent to which it can do so may be limited. It is hoped that information about timing of birth can be used by the NHS to inform planning both levels of staffing in terms of midwives and obstetricians and in detailed rostering, with the aim of trying to match the numbers of women in labour and giving birth and the numbers of midwives available and the availability of obstetric support should complications arise.

The University of Oxford was doing preparatory work before applying for an extract of the pseudonymised linked dataset for the purpose of a separate project called Tracking the Impact of Gestational Age on Health, Educational and Economic outcomes: a Longitudinal Record Linkage Study (TIGAR). This has now been agreed by NHS Digital under a separate Data Sharing Agreement, reference DARS-NIC-09637-Y8T1N.

In advance of that application for approval, the TIGAR study's Principal Investigator and a co-investigator, both of whom are employed by the University of Oxford at the National Perinatal Epidemiology Unit (NPEU), have been supporting the personnel from City, University of London by undertaking quality assurance and data cleaning exercises to assure and improve the quality and completeness of matching the birth records with the HES records including subsequent admissions. For clarity, under this Data Sharing Agreement, the principal investigator and co-investigator of the TIGAR project are the only personnel from the University of Oxford who are permitted to access the data and access is for the purpose of quality assurance and data cleaning. Although the bulk of this work has now been completed, these personnel may still need occasional access for checking purpose while writing this work up for publication. No other analyses of the data may be undertaken for the purpose of the TIGAR study under this Agreement and no other individuals from the University of Oxford may be granted access to the data.

All individuals accessing the data work under the supervision of City, University of London under conditions defined by ONS when carrying out the work, using ONS secure facilities that are required when handling identifiable data. No record level data may be accessed outside of the secure environment of the SRS.

Access to identifiers is restricted to these researchers from the University of Oxford and the individuals working at the linkage and data cleaning stage only.

Yielded Benefits:

The establishment of the research database permits additional research into maternity and its outcome. This database provides a more complete resource than any of the datasets individually by combining birth registration, birth notification and HES. This has enhanced HES by linking it to a fuller and more complete dataset and also adding variables which are not in Maternity HES. The database will not be updated with more recent data for the follow-on project. This is because the aim of this project is to analyse the data already held and no new data are requested. On the other hand, as the methods have been established, there is a potential to continually update the linkage to enable this work to reach its full potential by mainstreaming it, so that is updated annually to produce timely linked data for both and the production of national statistics. Administrative Data Research UK, which has been established to transform the way researchers access public sector data in the countries of the UK by joining up the data and facilitating safe and secure access to create a resource which will give insights into how our society and economy function is keen for this to happen and discussions have already started with the Office for National Statistics about enabling this. The establishment of the database in its current form was funded as part of the third project Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for the NHS, which has yielded the following actual and expected benefits: The aim of the parts of the project completed so far was to provide a better understanding of daily, weekly and seasonal variations in patterns of birth and this has been achieved. The next steps is to ascertain the impact of these differences on variations observed in outcome, in order to assess the extent to which these reflect selection and to inform improvements in the planning of maternity services. The analyses done so far show the extent of daily and weekly variations in numbers of singleton births and these have implications for the planning and staffing of maternity services. This and the other work so far has been described in detail in a final report to NIHR published in 2019 and now available in NIHR Journals Library. Meanwhile, the results have been presented and discussed at conferences attended by researchers, professionals and service users and prompted considerable interest and discussion about the implications of the results for the services they provide and use. Further research using the linked dataset: Other researchers have shown interest in using the linked dataset. So far, one project, Tracking the Impact of Gestational Age on Health, Educational and Economic outcomes: a Longitudinal Record Linkage Study (TIGAR) is well under way, funded by the MRC, as mentioned above. A researcher at the Institute of Child Health, UCL obtained ONS approval for linkage of data about births around 2011 to the census. She then successfully applied for ethics and Section 251 permission and funding and for a Data Sharing Agreement DARS-NIC-234656-C3J1D-v0.11 approving linkage of the database to Census 2011 data for mothers who gave birth during the year preceding and following the census date and to postcode level data on air pollution and building characteristics. The linkage will be done by the Office for National Statistics and the linked dataset will be provided to UCL without identifiers. The project will investigate association between housing, air pollution and respiratory infections in children. City, University of London has had exploratory discussions with other interested researchers. The NIHR-funded project had the support of the Chief Executive of the Royal College of Midwives and of the Royal College of Obstetricians and Gynaecologists, both of which provided letters of support.

Expected Benefits:

The analyses funded in the follow-on project will investigate how these patterns differ between maternity units and how the outcome of pregnancy varies according to the day and time of births. Analyses of outcomes in other projects done so far in the UK have either been restricted to day of the week or have simply dichotomised births into in and out of hours. The linked data will enable a more detailed analysis by time of day and night. They will give insights into whether the safety of birth varies by time of day and whether any variations observed are a reflection of differences in the characteristics of women or the type of obstetric intervention they undergo.

This new research will benefit patients and the NHS by describing current variation in the timing of births and their outcome in England and Wales as a whole and variations between maternity services in relation to their size and levels of intervention in the onset of labour and in delivery. This should inform local decisions about the needs for midwifery and obstetric staffing by time of day and the deployment of staff available as well as decisions about service configuration. This is in the public interest as previous analyses did not take account of the extent to which obstetric intervention affected the time at which women give birth and implied that birth out of hours was unsafe, without producing evidence to support this.

Retrospective analyses of routine data will provide important descriptive evidence about the issues raised here. In addition, although by their very nature, they will not be able to answer questions about causality they will provide a key baseline and give rise to questions which can be subsequently be tackled using other methods.
As with the analyses published so far, the team working on the ESRC-funded follow up project will also aim to disseminate the results as widely as possible to service users and professionals as well as in peer reviewed journals. A journal article reporting analyses of the times at which women give birth was widely reported in the press, being covered by BBC News, The Times, Evening Standard, Daily Express, ITV and many other outlets including an interview on the BBC News Channel. It was also disseminated directly to service user groups, It is therefore likely that results from the follow on project will also receive similar coverage and influence the staffing practices of maternity units.

Additional resources would be needed to survey individual maternity units to directly assess the impact of this information on their practices, but it is hoped that it will influence their staffing rosters.

Outputs:

The output of the data linkage and subsequent quality assurance was the creation of the research database which is stored within ONS, accessed only via the SRS subject to the controls outlined above. The database was created as an output of the previous project. Some of the quality assurance was undertaken as part of the project and further quality assurance was undertaken by the two TIGAR researchers from the University of Oxford. There is still further quality assurance work to be done and quality assurance is included in the follow-on project.

From the project, Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for the NHS, the outputs listed below have been delivered or are expected. Further articles are expected from the follow-on project.:

City, University of London submitted four articles to peer reviewed journals and a final report to the National Institute for Health Research (NIHR). Two articles have been published by BMJ Open, a weekly peer reviewed medical journal and a further article was published in PLOS1, a peer reviewed open access scientific journal, and the fourth is being revised before resubmission. NIHR has published the final report in its online journal. City, University of London has also given oral and poster presentations at a number of conferences, as shown on the list below. Further articles will be written, based on work already partly completed and the further analyses which have now been funded.

City, University of London will write and submit a further article summarising findings to Significance, the Royal Statistical Societys magazine which aims to popularise statistics. This will be submitted for publication within the next year.

Once the further analyses are complete, results in the form of aggregated statistics, which may include some sub-national results with small numbers suppressed, graphs and diagrams and the outputs of statistical analyses will be written up as further articles for submission to peer reviewed journals.

The study team plan to submit at least three articles to peer reviewed journals, one on the outcome of births by time of day and day of the week, one on differences between maternity units and one on the linkage and analysis of data about births in Wales. When they are accepted, the study team will work with Citys press office to maximise coverage. A recent article on the timing of birth was reported in the national media and to date there have been over 370 press reports.

Opportunities will be to present findings at professional conferences and aim to contribute to publications, such as the research summaries included on the Royal College of Midwives magazine, Midwives.

Public and Patient Involvement is at the heart of this project and reaches well beyond the minimum required by funders. Results in the form of aggregated statistics, which may include some sub-national results with small numbers suppressed, will be provided to the National Childbirth Trust (NCT) for its work in providing services and materials to prospective and actual parents.

A member of the project team, with extensive experience of research engagement, will disseminate the findings to parent representatives and patient advocates serving on maternity services liaison committees and labour ward forums with the aim of highlighting research findings and service users views and priorities to clinical managers and commissioners. In the follow on project, the person concerned will be employed by City, University of London.

NCT also involves its members in representing the views of service users to the maternity services and also participating in research projects to represent users views. Three meetings of NCT members and others who are service user representatives on Maternity Services Liaison Committees and Maternity Voices Partnerships to do this were held in relation to the third project. They were useful in exploring service users concerns about possible temporal variations in the safety of birth, including positive and negative implications of birth at night and at weekends. Two more are planned as part of the follow-on project. No one involved in this aspect of the project has access to individual service users records.

The following outputs have been produced to date:

Articles in peer reviewed journals:

Dattani N, Macfarlane A. Linkage of Maternity Hospital Episode Statistics data to birth registration and notification records for births in England 2005-2014: methods. A population-based birth cohort study. BMJ Open 2018;8:e017897. doi:10.1136/ bmjopen-2017-017897

Harper G. Linkage of Maternity Hospital Episode Statistics data to birth registration and notification records for births in England 20052014: Quality assurance of linkage of routine data for singleton and multiple births. BMJ Open Mar 2018, 8 (3) e017898; DOI: 10.1136/bmjopen-2017-017898

Martin P, Mario Cortina-Borja M, Newburn M, Harper G, Gibson R, Dodwell M, Dattani N, Macfarlane A. Timing of singleton births by onset of labour and mode of birth in NHS maternity units in England, 2005 2014: a study of linked birth registration, birth notification, and hospital episode data. PLoS ONE 13(6): e0198183. https:/doi.org/10.1371/journal.pone.198183.
Dattani N. Macfarlane A. Analysis of births at home in England and Wales by time of day and day of the week using linked administrative data. Submitted to Birth. Rejected with suggestions for a revised article which is being drafted and submitted.

Other articles

Macfarlane A. Day and time of birth and mode of onset and birth. Research Summary 3. Practice: Research summary 3. Midwives / Winter 2018; 34. cm.org.uk/midwives

Final report to NIHR

Macfarlane A, Dattani N, Gibson R, Harper G, Martin P, Scanlon M, Newburn M, Cortina-Borja M. Births and their outcomes by time, day and year: a retrospective birth cohort data linkage study. Health Serv Deliv Res 2019;7(18).

Rapid response to BMJ

Association between day of delivery and obstetric outcomes: observational study was published as a BMJ Rapid Response 25 November 2015. URL: http://www.bmj.com/content/351/bmj.h5774/rr-7

Oral presentations:

Dattani N, Macfarlane A, Datta-Nemdharry P. Using data linkage to create a national database of birth and maternity data. Presentation at Royal Statistical Society Conference, Sheffield, September 2014.

Macfarlane AJ. Care.data: Bungled opportunity or unjustified intrusion? Invited presentation to Royal Statistical Society meeting. October 7 2014.
Macfarlane A, Dattani N. Using linkage of administrative data to build a national database for analysis of birth and its outcome in England and Wales. Presentation at the Administrative Data Research Network Conference, Edinburgh, June 1-2 2017.

Harper G. Quality Assuring Linked Birth Registration and Hospital Episode Statistics Delivery Records results and lessons learned. Presentation at the Administrative Data Research Network Conference, Edinburgh, June 1-2 2017.

Harper G. Insights on Third Party Linkage and Data Quality from Quality Assuring Linked Birth Registrations and HES Delivery Records in England 2005 to 2014. Oral presentation at Royal Statistical Society International Conference, University of Strathclyde, Glasgow, September 4-7 2017.

Macfarlane A, Martin P, Cortina-Borja M. Dattani N, Harper G, Newburn M. Gibson R. A time to be born? Oral presentation at Royal Statistical Society International Conference, University of Strathclyde, Glasgow, September 4-7 2017.

Martin P, Cortina-Borja M, Dattani N, Harper G, Gibson R, Newburn M, Dodwell M, Macfarlane A. Variations in numbers of births by day of the week in relation to onset of labour and mode of giving birth, England 2005-2014. Oral presentation at Royal Statistical Society International Conference, University of Strathclyde, Glasgow, September 4-7 2017.

Cortina Borja M, in collaboration with Macfarlane A, Dattani N, Dodwell M, Gibson R, Harper G, Martin P, Newburn M. Modelling numbers of births by day of the week in relation to onset of labour and mode of giving birth in England 20052014. Talk to RSS South West local group, Plymouth University, 20th February 2019.

Macfarlane A, Dattani N. Building a birth cohort of births and their outcome in England and Wales using linkage of administrative data. Accepted for oral presentation at the 4th International Conference on Administrative Data Research, Cardiff, Wales, 9-11 December 2019.

Macfarlane A, Dattani N. Analysis of births England and Wales by time of day and day of the week and place of birth using linked administrative data. Accepted for rapid fire presentation at the 4th International Conference on Administrative Data Research, Cardiff, Wales, 9-11 December 2019.

Coathup V, Macfarlane A, Quigley M. Evaluating record linkage of birth registration and notification records to Maternity Hospital Episode Statistics and childhood hospital readmissions: Singleton births in 2005 and 2006 across England. Accepted for oral presentation at the 4th International Conference on Administrative Data Research, Cardiff, Wales, 9-11 December 2019.

Conference posters:

Dattani N, Macfarlane A. Analysis of births at home in England and Wales by time of day and day of the week using linked administrative data. Poster presented at Farr Institute International Conference, University of St Andrews, 26 28 August 2015.

Macfarlane A, Dattani N. Using data linkage to build a national database of data about birth and its outcome for policy analysis in England and Wales. Poster presented at Farr Institute International Conference, University of St Andrews, 26 28 August 2015.

Harper G, Macfarlane A, Dattani N, Dodwell M, Newburn M, Gibson R, Cortina-Borja M, Martin P. Analysing the daily, weekly and yearly cycles of births and their implications for the NHS using linked data. Analysing the daily, weekly and yearly cycles of births and their implications for the NHS using linked data. Poster presented at the International Population Data Linkage Conference, Swansea, Wales, 24-26 August 2016.

Macfarlane A, Dattani N, Harper G, Cortina-Borja M, Martin P, Gibson R, Dodwell M, Newburn M. Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for midwifery care. Poster presented at the Royal College of Midwives Annual Conference. Harrogate, October 19-20 2016.

Macfarlane A, Martin P, Cortina-Borja M, Newburn M, Harper G, Gibson R, Dodwell M, Dattani N. A time to be born? Poster presented at the 12th International Normal Labour and Birth Research Conference, October 2nd to October 4th, 2017, Grange Over Sands, Cumbria, England. Winner of the Scientific Review Team Prize.

Macfarlane A, Martin P, Cortina-Borja M, Newburn M, Harper G, Gibson R, Dodwell M, Dattani N. Births: the weekly cycle. Poster presented at the 12th International Normal Labour and Birth Research Conference, October 2nd to October 4th, 2017, Grange Over Sands, Cumbria, England

Processing:

City, University of London had previously linked birth registration and notification data, previously known as NHS Numbers for Babies (NN4B) data to Maternity HES for births in 2005 to 2007. ONS supplied identifiers consisting of mothers and babys NHS numbers, postcode of residence, mothers and babys date of birth and babys sex from its births files together with a unique record ID to NHS Digital, linked with Maternity HES delivery and birth records and extracted the linked data. The linked data including a unique record ID were then sent back to ONS by NHS Digital. These records were then used the record ID to link the HES records back to the data in the ONS births files in the VML.

For the current project, the linkage algorithm used in the second study was revisited in collaboration with NHS Digitals linkage team. An algorithm modified from NHS Digitals standard algorithm was compared with the algorithm used previously. It was found to perform better and used to re-link the data for all the years. The time period was further updated. Linked birth registration data and notification data for births in 2005 to 2014, previously linked by ONS, were further linked to Maternity HES delivery and birth records. In addition, there were further data linkages of individual level HES records of subsequent admissions of mothers and babies to their birth and delivery records. The method for this was as follows:

i. Identifying details from ONS births data were securely transferred to NHS Digital by ONS;

ii. NHS Digital linked the identifiers to HES delivery and birth records;

iii. NHS Digital also extracted the HES delivery and birth records not linked to the identifiers supplied by ONS.

iv. NHS Digital securely transferred the data to ONS;

v. ONS attempted further linkage of the non-linked HES delivery and birth records with ONS birth records to try to improve the linkage rate;

vi. ONS added the linked HES delivery and birth records into the database, along with the linked birth registration and NN4B data, as identifiable data;

vii. Quality assurance and data cleaning work is being carried out within ONS VML by members of the research team and the two TIGAR researchers from the University of Oxford as specified above. Quality assurance and data cleaning of mothers delivery records has been completed by City University of London and the results have been published. The TIGAR researchers have undertaken quality assurance of birth records of babies born in 2005 and 2006 and any records of their subsequent admissions to hospital and have written up the results. They may need to access the data with identifiers to respond to queries from journal reviewers. Quality assurance and data cleaning of the rest of the data are still to be done by City University of London.

viii. When this is completed, the cleaned files will be retained on one of ONS' own servers;

ix. De-identified files of data were put into the VML (now known as the SRS) for access for analysis by researchers. These files contained no NHS Numbers. Dates of birth and death were included as these were essential for the purpose of the analyses being undertaken for the project Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for the NHS. Individuals names have never been provided to the project and no other identifiers have been provided. Full dates of birth and death were not included in the data provided to the TIGAR researchers at the University of Oxford.

The data are linked and stored within the ONS Secure Research Service (SRS). Data can only be accessed within the SRS by individuals who meet the criteria described above with authorisation from ONS Head of Vital Statistics Output Branch and Information Guardian.

All analyses will be undertaken in the SRS. All outputs from research in the SRS are checked by ONS staff working in the SRS team before being released to ensure compliance with the relevant disclosure rules and to ensure that respondent confidentiality is protected at all times.

For the purpose of the project Births and their outcome: analysing the daily, weekly and yearly cycles and their implications for the NHS, funded by NIHR, only authorised researchers from City, University of London, including a contractor and a member of UCL staff with a collaborative contract with City were granted access to the pseudonymised data within the SRS.

The aims of City University of Londons first analyses, were to describe and analyse daily, weekly and yearly cyclical variations in births and their outcome and explore the potential implications of the patterns observed for NHS staffing and for service users.

Data were to be cross-tabulated and aggregated data plotted to describe daily, weekly and annual cycles in numbers of births and their outcome in terms of birthweight, gestational age, mortality and morbidity recorded at delivery and any subsequent hospital episodes. Preterm and term births were to be analysed separately and subdivided according to whether or not the onset of labour and the method of delivery were spontaneous. Births occurring at home and multiple births were to be analysed separately and it was anticipated that the main statistical modelling would focus on singleton births in hospital. Patterns of births were to be analysed nationally. Where possible, they were to be analysed by hospital, maternity unit or NHS trust aggregated by levels of obstetric intervention in order to analyse associations between known differences in levels of obstetric intervention rates and outcome by time of data and day of the week.

Following the end of the previous project, it was not possible to complete these analyses . Analyses of outcomes in terms or mortality and morbidity recorded at delivery and any subsequent hospital episodes are still outstanding, as are analyses of births at home and multiple births and analyses by hospital, maternity unit or NHS trust. Further funding has been obtained from the Economic and Social Research Council (ESRC) for a follow-on project Implications of time of day and day of the week for the outcome of birth to work on outstanding analyses. The term implications was used in the project title to include associations with the outcomes described above.

As with the analyses to date, these further analyses will be undertaken in the secure environment of the SRS and only disclosure-controlled outputs will be released by ONS. These outputs comply with the rules on small number suppression outlined in the HES Analysis Guide and by ONS.