Title: Births and their outcome: analysing the daily weekly and yearly cycles and their implications for the NHS
Funder: Department of Health (England)

Abstract: Analyses since the 1970s have shown that maternity outcomes have differed by day of the year day of the week and time of day. It is unclear to what extent this reflects differences in characteristics of women giving birth efforts made to intervene selectively in the onset of labour or in delivery or in health services’ workforce factors notably numbers or seniority.(12) Previous analyses of data for England and Wales for the years 1970-76(3) and 1979-96(4) were based on aggregated counts and mortality was not disaggregated by cause. Analyses by time of day method of onset of labour and gestational age were not possible in these analyses as the relevant data items were not available at a national level for England and Wales. Recent developments in data recording and linkage have changed this. As a by-product of the change to allocation of babies’ NHS Numbers at birth the time of day of birth is now recorded in national datasets. As a result of a project led by City University London to link birth registration data with this NHS Numbers for Babies dataset the Office for National Statistics (ONS) now has national data on gestational age and time of day of birth for years from 2005 onwards.(5|) Linkage with Maternity Hospital Episode Statistics (HES) and corresponding data for Wales in a project funded by the MRC means that data are available about the onset of labour and method of delivery for most although not all deliveries in the years from 2005 to 2007 and the techniques developed in this project can be used to link these data for subsequent years.(67) As morbidity in mothers and babies is also a matter of concern it would therefore be useful to extend this database by linking births to data about subsequent hospital admissions and readmissions of mothers and babies recorded in HES and the Patient Episode Database Wales (PEDW).AimsThe overall aim is to describe and analyse daily weekly and yearly variations in births and their outcome and explore the potential implications of the patterns observed for NHS staffing and for service users.MethodsAs the data for 2005 to 2007 are already linked analyses of daily weekly and annual cycles will start during the first six months of the project using these data. In parallel with this files of key data items from linked birth registration / NHS Numbers for Babies records for births in 2008 to 2011 will be sent to the Information Centre for Health and Social Care (IC) and NHS Wales Informatics Service (NWIS)for linkage to data about care at delivery from Maternity HES and National Community Child Health Database (NCCHD) / PEDW using the techniques developed for births in 2005 to 2007.(67) We have continued to renew and extend the Section 251 permission given initially to link data for the years 2005 to 2007. It has now been renewed and extended to cover the years 2008 to 2012. Once the further linkages are completed the whole file will be combined for analysis during the second six months of the project.A new application for Section 251 permission has been submitted to extend the linkage to records of subsequent hospital care. Once it is obtained techniques for linkage of records of neonatal care and other postnatal hospital admissions of mothers and babies to birth registration / NHS Numbers for babies records will be piloted on a sample of records and then used for all the births. It is hoped that this will be achieved in time for analyses to start early in the second year of the project.Analysis Individual linked records from birth registration NHS Numbers for babies Maternity HES and its Welsh counterparts will be cross-tabulated and aggregated data will be plotted graphically 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 will 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 will be analysed separately and the main statistical modelling will focus on singleton births in hospital. Appropriate descriptive and inferential statistical techniques(8-12) will be used to analyse daily weekly and yearly cycles in births and their relations to outcomes of pregnancy. Patterns of birth will be analysed nationally and where possible by hospital or NHS trust and will take account of available staffing and other data. This is challenging because of the many changes in configurations of services. For this reason we have involved BirthchoiceUK which uses data from routine sources to maintain a web site to provide information for the public about maternity services. It is important to attempt this task as analyses have shown that caesarean section rates show unexplained wide differences even after adjustment for case mix and other local factors.(13) Therefore if possible account will be taken of overall levels of obstetric intervention. Analytical work will again be undertaken in the secure environment of the Virtual Microprocessor Laboratory (VML) at the ONS.Potential benefits to the NHSThese analyses should provide information about the ways in which numbers of births and their outcome vary throughout the day week and year both spontaneously and as a consequence of obstetric intervention. Analyses by NHS trust and maternity unit will aim where possible to examine associations with midwifery and medical staffing using workforce data from the Information Centre for Health and Social care and Health Statistics Wales and with characteristics of individual units using data compiled by BirthchoiceUK for its web site. The analyses are innovative in examining the full weekly cycle and the potential for varying selection factors for intervention rather than a simple dichotomy into in and out of ‘hours’. The results will be discussed with key user groups and a multidisciplinary advisory group made up of representatives of relevant professional and user groups and researchers.References1. Young D. When was the baby born: Reflecting on the time of day day of week mode of delivery and birth outcomes. Birth 2011; 38: 1-2.2. Mathers CD: Births and perinatal deaths in Australia: variations by day of week J Epidemiol Community Health 1983;37:57-62 doi:10.1136/jech.37.1.573. Macfarlane AJ. Variations in numbers of births and perinatal mortality by day of week in England and Wales. British Medical Journal 1978;2:1670 1673.4. Hawe E Macfarlane AJ Bithell J. Daily and seasonal variation in live births stillbirths and infant mortality in England and Wales 1979-96. Health Statistics Quarterly 2001; 9: 5-15.5. Moser K Macfarlane A Chow YH Hilder L Dattani N. Introducing new data on gestation-specific infant mortality among babies born in 2005 in England and Wales. Health Statistics Quarterly 2007; 35: 13-27.6. Dattani N Datta-Nemdharry P Macfarlane A. Linking maternity data for England 2005-06: methods and data quality. Health Statistics Quarterly 2011; 49: 53-76.7. Datta-Nemdharry P Dattani N Macfarlane A Thomas G. Linking maternity data for Wales 2005-07: methods and data quality. Health Stat Q. 2012 Summer;(54):1-24. http://www.ons.gov.uk/ons/rel/hsq/health-analysis/linking-maternity-data-for-wales--2005-07--methods-and-data-quality/index.html.8. Venables WN and Ripley BD. Modern Applied Statistics with S-PLUS 2nd edition New York: Springer 1999.9. Ramsey JO and Silverman BW. Functional Data Analysis 2nd edition. New York: Springer 2005.10. Fisher NI Statistical Analysis of Circular Data. Cambridge: Cambridge University Press 1995.11.Barnett AG and Dobson AJ Analysing Seasonal Health Data Springer: New York 2010.12. R Core Team. R: A Language and Environment for Statistical Computing. The R Foundation for Statistical Computing Vienna 2012.13. Bragg F Cromwell D Edozien LC Gurol-Uganci I Mahmood TA Templeton A van der Meulen JH. Variation in rates of caesarean section among English NHS trusts after accounting for maternal and clinical risk: cross sectional study. BMJ 2010; 341:c5065.


Research activity codes: 8.1 ORGANISATION AND DELIVERY OF SERVICES
Health categories: REPRODUCTIVE HEALTH AND CHILDBIRTH