The voice of the infant: towards understanding the excess infant mortality in Queensland

Background: Queensland’s infant mortality rate (IMR) is higher than other Australian jurisdictions and the disparity is under-researched, particularly for Sudden Unexpected Deaths in Infancy (SUDI). Informed by Triple Risk and Adverse Childhood Events (ACEs) constructs, and with a focus on shared infant sleep, this thesis analyses risk factors to identify opportunities for prevention. Methods: Three analytical chapters include: extraction and reconfiguration of reported demographic data to compare international and Australian jurisdictions; multivariate analysis of linked administrative data (a six-year Queensland births cohort) to analyse pre-natal risk factors for infant death; and analysis of findings from a series of SUDI and post-neonatal deaths, incorporating reviews by the Queensland Paediatric Quality Council expert panel. Results: I confirmed that Queensland’s IMR was significantly higher than the rest of Australia for neonatal, post-neonatal, ill-defined, and non-Indigenous deaths, but not Indigenous deaths. Perinatal factors significantly associated with acquired cause of death after multivariate analysis (young motherhood, higher birth order, smoking in pregnancy, late antenatal care, preterm gestation, maternal obesity, Male infant), were identifiable but not modifiable by mid-pregnancy. Indigeneity and residence in low socio-economic areas were not associated with acquired cause of death after adjustment for other factors. Correcting for post-conceptional age at SUDI shifts the peak incidence to age less than 44-weeks post-conception. Death scene description, post-mortem investigation, and clinico-pathological correlation were inadequate in more than 30 percent of SUDI cases. After panel review, deaths attributed to suffocation and undetermined causes increased, acknowledging the contributory role of unsafe sleep in almost all SUDI, and the rarity of other sufficient causes. SUDI occurred in the setting of high levels of multigenerational social adversity. Conclusion: SUDI is an important contributor to Queensland’s excess infant mortality. The vulnerability to SUDI of infants born before 40-weeks gestation provides a new focus for prevention. The association of maternal pre-natal risk factors with maternal ACEs is consistent with the multifactorial genesis of SUDI and warrants further research. Opportunities for prevention are hampered by inadequate death investigation. SUDI occur in families experiencing multigenerational adversity, for whom engagement and support may help to mitigate highly prevalent risk factors including unsafe sleep