Approaches in landscape fire smoke pregnancy research and the impact on offspring: a review on knowledge gaps and recommendations

The increase in wildfires and bushfires due to climate change means that more people, including pregnant women and their fetuses will be exposed to landscape fire smoke. Although there is evidence to suggest that pregnancy landscape fire exposure is associated with lower birth weight, preterm birth and pregnancy loss, there is a lack of information on many other perinatal outcomes, as well as information on subsequent respiratory outcomes in children. Furthermore, due to the generally short term (hours/ days) and intermittent nature of landscape fire smoke exposure, the knowledge to date has largely relied on natural experiments and ecological studies which can be subject to misclassification of exposure and a lack of precision. On the other hand, general urban outdoor air pollution exposure during pregnancy and subsequent perinatal and respiratory effects has been well studied. In particular, as air exposure modelling has improved so have the adaptations of methods to analyze the effects of air pollution exposure during pregnancy enabling critical windows of exposure to be identified. In this narrative review we summarize the current state of knowledge about the perinatal and respiratory effects of pregnancy landscape fire and particulate matter <2.5μm in diameter (PM_2.5) air pollution exposure, including a comment on analysis methods to date, and an assessment of how methodologies used in general air pollution research in relation to pregnancy exposure can be further harnessed for landscape fire smoke exposure pregnancy research.