Summary
This report analyses the relationship between early childhood mortality in New South Wales and maternal and baby characteristics at the time of birth (perinatal conditions) using a linked data set created for this project.
This summary focuses on the key findings from the major components of this report in chapters 5 and 6 (multivariate regression analyses).
A stand-alone Summary report is also published separately, which provides further details than in this executive summary, including on the study design and methods used, data linkage process, and other results from the preliminary descriptive analyses presented in other parts of this report.
The study population consists of all babies born in New South Wales between 2005 and 2018. Their perinatal conditions are derived from the NSW Perinatal Data Collection. These birth cohorts were linked to NSW and national death registration records to identify the children who died by the end of 2019, and their age at death. In addition, several area-level socioeconomic status indicators, based on the usual area of residence of the mother when giving birth, were added to the linked data set from the Socio-Economic Indexes for Areas (SEIFA) and the Australian Early Development Census (AEDC).
The study was commissioned by the NSW Child Death Review Team (CDRT) and builds on previous analyses by the Australian Institute of Health and Welfare (AIHW) of the CDRT Register of Child Deaths (NSW CDRT 2014, 2018). Earlier studies focused on analysing data available only for the children who had died. This study extends the scope of analyses by connecting these death records to the birth records of the full cohorts of babies born in New South Wales. This allowed risk factors for child mortality to be better identified by directly comparing the characteristics of babies who have died with those of babies who have survived to specific ages.
The analysis using linked birth and death data changes the study focus slightly – from the analysis of all NSW-registered deaths, as in most previous studies, to the analysis of deaths among all NSW-born babies.
The NSW perinatal and birth registration datasets identified 1,393,488 unique records of live-born babies in New South Wales between 2005 and 2018 (an average of around 99,500 births per year). The PDC records alone identified 1,337,341 unique live-born babies in NSW (an average of around 95,500 per year). The latter count represents the total number of births available for analysis in this study because the effects of perinatal conditions on mortality can be considered only for births with a full PDC record.
From this total number of births, the data linkage identified 3,715 child deaths under age 5, most of which were deaths under age 1 (3,067 or 83% of total under-5 deaths).
The linked data file also identified around 60,300 Aboriginal and Torres Strait Islander children born in New South Wales during this period, based on Indigenous status as recorded in either the birth or death records. Among them, 383 had died under age 5, of whom 309 (81%) had died under age 1.
The risk factors for early childhood death in New South Wales are analysed separately for:
- death under age 1 of all children in these birth cohorts
- death between ages 1 to 4 of all children in these birth cohorts
- death under age 1 among Indigenous children only.
For death under age 1 of all children (where the total number of deaths is sufficiently large) separate analyses are done for 3 birth cohorts: babies born between 2005–2010, babies born between 2011–2014 and babies born between 2015–2018.
Acknowledgments
Abbreviations
Executive summary
- Key findings
- Death under age 1 – all children
- Death between ages 1 to 4 – all children
- Death under age 1 – Indigenous babies
- Area-level socioeconomic status variables
- Interpretation of results on the Indigenous status variable in regression models on the risks of dying among all children
- ‘Top 8’ list of significant perinatal characteristics
1. Introduction
- NSW Child Death Review Team
- Background
- Project objectives
- Scope of birth cohorts specified in linked data
- Report structure
2 . Methodology and summary data linkage outcomes
- Data linkage design
- Step 1: identify the full cohort of babies
- Step 2: link the birth and death records
- Area-level data
- Summary of mortality indicators in the linked file
- Data analysis plan
- Deriving Indigenous status
3. Summary mortality rates and time trends from linked data
- Aggregate child mortality rates
- Cohort-specific mortality by Indigenous status
- Cause of death differences by age at death and Indigenous status
4. Differing characteristics of children who died and children who survived
- Key risk factor differences
- Mortality rates by perinatal characteristics
- Perinatal characteristics with largest differences in mortality
- Differences by Indigenous status and remoteness areas
- Extension to multivariate analyses of difference
- Key risk factors and mortality rates by perinatal characteristics for Indigenous children
5. Multivariate analyses of early childhood deaths – all children
- Factors related to deaths under age 1
- Marginal effects of factors related to deaths under age 1
- Factors related to deaths under age 1, excluding deaths within 7 days of birth
- Comparison of selected results on risks of dying by age 1, including and excluding early deaths within 7 days after birth
- Factors related to deaths between ages 1 to 4
6. Multivariate analyses of deaths under age 1 – Indigenous infants
- Factors related to Indigenous child death under age 1
7. Overview, contributions and some limitations and extensions
- Contribution to the literature
- Some limitations and suggestions for further research
References
Appendix A.1 – Appendix to Chapter 4
Appendix A.2 – Appendix to Chapter 5
- Guide to key terms and concepts related to logit regression models
- Guide to presentation of the full regression results
Appendix A.3 – Appendix to Chapter 6
Appendix B – Summary of data linkage processes and outcomes
- Study cohort
- Summary of data linkage to identify babies who died
- Summary of data linkage algorithm
- Indigenous births and deaths in linked data