Lifestyle, environmental and sociodemographic factors – the impact on stillbirth risk
Bowman A (1-4), Gomersall J (1,3), Sullivan T (1,3), Makrides M (1,3,4), Flenady V (2,5), Corey M (5), Middleton P (1-4)
(1) South Australian Health and Medical Research Institute, (2) Stillbirth Centre of Research Excellence, (3) University of Adelaide, (4) Targeted Nutrition for Mother and Child Centre of Research Excellence, (5) Mater Research
The stillbirth rate in Australia has remained stagnant at 7.4/1000 births for over two decades. Stillbirth causes far-reaching devastation and grief for families, communities, health carers, and has extensive economic impacts. We aim to expand on a 2011 systematic review of stillbirth risk by identifying and updating evidence on lifestyle and environmental risk factors while including evidence on social determinants of stillbirth in high-income countries.
Databases were searched for studies examining risk factors of interest published between 1998-2018. Population/institutional cohort and case control studies were selected for inclusion. Reviews were hand-searched for studies of interest. Identified studies were screened by 2 reviewers and quality assessed using the RTI tool of assessment for observational studies.
Of 65,784 search results, 412 studies were included with 32 factors of interest were identified. Results demonstrate high awareness and publication of factors such as maternal age, smoking and maternal ethnicity, yet many publications differed in their exposure measure method, as well as their stillbirth definitions. A meta-analysis for smoking as a dichotomous value included 74,975,484 pregnancies in 38 studies, the aOR was found to be 1.48 (1.36-1.60), but with high heterogeneity subgroup analysis is warranted due to large difference in populations and clinical settings.
The results of this research provide understanding of the combined impact that lifestyle and social determinants have on stillbirth risk in high income countries. Although a universal definition of stillbirth has been advised previously, there continues to be large variation in definitions used causing high heterogeneity between studies as mentioned in the 2011 Lancet systematic review. The variation between population characteristics and clinical settings could explain this result in comparing data from multiple high income countries. Results of this research will form the evidence base for tailoring antenatal care bundles to decrease stillbirth risk.
Ethics approval was not sought for the conduct of this systematic review and meta-analysis.