Double jeopardy-pregnancy and birth during a catastrophic bushfire event followed by a pandemic lockdown, a natural experiment
Pregnant women who were exposed to both bushfire smoke and COVID-19 restrictions faced a higher risk for adverse maternal health and birth outcomes.
Cite this Article
Brew, Bronwyn K., et al. “Double Jeopardy-Pregnancy and Birth During a Catastrophic Bushfire Event Followed by a Pandemic Lockdown, a Natural Experiment.” Environmental Research, vol. 214, 2022, pp. 113752–113752, https://doi.org/10.1016/j.envres.2022.113752.
Brew, B. K., Donnolley, N., Henry, A., Dahlen, H., Jalaludin, B., & Chambers, G. M. (2022). Double jeopardy-pregnancy and birth during a catastrophic bushfire event followed by a pandemic lockdown, a natural experiment. Environmental Research, 214, 113752–113752. https://doi.org/10.1016/j.envres.2022.113752
Brew, Bronwyn K., Natasha Donnolley, Amanda Henry, Hannah Dahlen, Bin Jalaludin, and Georgina M. Chambers. 2022. “Double Jeopardy-Pregnancy and Birth During a Catastrophic Bushfire Event Followed by a Pandemic Lockdown, a Natural Experiment.” Environmental Research 214: 113752–113752. https://doi.org/10.1016/j.envres.2022.113752.
Authors
This article was written by , , , , and , and was originally published by Environmental Research in November of 2022In Australia, bushfires are a common natural disaster affecting the nation. During the Black Summer bushfires of July 2019 to February 2020, over 6.7% of New South Wales was affected, with 2439 homes being destroyed and 33 people killed. The duration and intensity of these fires led to catastrophic air quality impacts, with 81 days of poor air quality from November 2019 to January 2020, more days than the last ten years of poor air quality days combined. Few studies have examined how exposure to bushfire smoke during pregnancy impacts the health of pregnant women and their newborn babies. Mixed results associate exposure to bushfire smoke with decreased birthweight, although additional research is needed.
The disaster event of the bushfires in Australia also overlapped with the beginning of the COVID-19 pandemic – and some research shows a correlation with COVID-19 lockdowns and an observed decrease in preterm births and an increase in stillbirths. Given the widespread impact of both COVID-19 restrictions and extreme fire risk worldwide, it is important to examine how both the pandemic and shifts in climate affect maternal health in order to protect vulnerable populations including pregnant women and babies. This natural experiment explores how both the Black Summer bushfires and the COVID-19 pandemic impacted birth outcomes in Australia.
Compared to births in previous years (unexposed to bushfires and COVID-19 restrictions), pregnancies with at least one month exposure to bushfires and/or COVID-19 restrictions faced increased risk of adverse health outcomes.
- Pregnancies exposed to bushfires and/or COVID-19 restrictions had an increased risk of prelabor rupture of membranes, unplanned cesarean sections, and high birthweight, as well as a slight increase in induced labor.
- Pregnancies exposed to Black Summer only had a decreased risk of low birthweight.
- While unexpected, these results may be a result of stress or a decrease in exercise due to the poor air quality.
- In the Black Summer & Pandemic 1 group, there was an increase in the risk of prelabor rupture of membranes, unplanned cesarean sections, planned cesarean sections, and low birthweight.
- In the Black Summer & Pandemic 2 group, there was a decreased risk for gestational diabetes and an increased risk for unplanned cesarean sections and high birthweight.
- In the Pandemic only group, there was a decreased risk for gestational diabetes and an increased risk for unplanned cesarean sections.
- Stillbirth rates were elevated for all exposure groups, though this finding was not significant.
This study emphasizes the danger of double-jeopardy, as being exposed to both bushfires and pandemic restrictions during pregnancy increases the risk of several adverse birth outcomes. With climate change increasing the prevalence of climate events and the lasting impact of the pandemic, it is important to continue investigating these effects on maternal health.
The population of this study is all women who gave birth between November 1, 2017 and December 31, 2020 across eight public hospitals in Sydney, Australia (60,054 births). The perinatal outcomes examined included gestational diabetes, pre-eclampsia, hypertension, prelabor rupture of membranes, mode of birth, induction of labor, stillbirth, birthweight, preterm birth, and size for gestational age. Given the intensity of the fires in the districts examined, the researchers indicate that it is safe to assume that all women giving birth from these areas were exposed to the bushfire smoke, justifying the natural experiment methodology.
To observe the impact of COVID-19 restrictions on birth outcomes, the researchers then separated births into two groups: pregnancies with exposure to bushfire smoke in utero or pregnancies with exposure to COVID-19 restrictions in utero. There was significant overlap in these groups, , thus the researchers also divided the pregnancies into four groups: Black Summer Only (born December 2019-March 2020), Black Summer & Pandemic 1 (conceived July-October 2019, born after COVID-19 restrictions began on April 1, 2020), Black Summer & Pandemic 2 (conceived November 2019-January 2020, born after COVID-19 restrictions began on April 1, 2020), and Pandemic Only (conceived February-March 2020). These cohorts were compared to pregnancies during the same periods from the previous two years (2017-2018) to minimize seasonality effects.
Cite this Article
Brew, Bronwyn K., et al. “Double Jeopardy-Pregnancy and Birth During a Catastrophic Bushfire Event Followed by a Pandemic Lockdown, a Natural Experiment.” Environmental Research, vol. 214, 2022, pp. 113752–113752, https://doi.org/10.1016/j.envres.2022.113752.
Brew, B. K., Donnolley, N., Henry, A., Dahlen, H., Jalaludin, B., & Chambers, G. M. (2022). Double jeopardy-pregnancy and birth during a catastrophic bushfire event followed by a pandemic lockdown, a natural experiment. Environmental Research, 214, 113752–113752. https://doi.org/10.1016/j.envres.2022.113752
Brew, Bronwyn K., Natasha Donnolley, Amanda Henry, Hannah Dahlen, Bin Jalaludin, and Georgina M. Chambers. 2022. “Double Jeopardy-Pregnancy and Birth During a Catastrophic Bushfire Event Followed by a Pandemic Lockdown, a Natural Experiment.” Environmental Research 214: 113752–113752. https://doi.org/10.1016/j.envres.2022.113752.
