PERINATAL OUTCOMES FOLLOWING BUSHFIRE SMOKE EXPOSURE IN WOMEN WITH ASTHMA

Abstract

Introduction: Climate change is leading to more frequent landscape fires globally. We aimed to investigate the perinatal effects of exposure to bushfire smoke during pregnancy in women with asthma. Methods: The study population included 1275 pregnant women with asthma and their babies from Newcastle, Brisbane, Sydney and Canberra (births 2013-2020). Asthma exacerbations were collected from questionnaires and perinatal data from medical records. First, a natural experiment design compared women from Newcastle who were pregnant for at least one month of the Eastern Australia bushfires Nov 2019-Jan 2020 (n = 76, average daily particulate matter (PM)2.5 12.1μg/m3) with women pregnant during similar months in the previous 6 years (n = 655, average daily PM2.5 7.3 μg/m3). Second, in the whole population, number of days exposed to bushfires over pregnancy and trimesters were compared to no exposure. Logistic regression with adjustment for socio-demographics, season of birth and sex was applied. Results: In the natural experiment, exposed women showed no differences for asthma exacerbations (adjusted odds ratios (aOR) 0.6, 95% CI 0.3, 1.2) compared to controls, however, infants had an increased risk of being preterm (aOR 2.7, 95% CI 1.2, 6.2), being low birth weight (aOR 2.5, 95% CI 1.2, 5.2) and admission to neonatal intensive care (NICU) (aOR 3.9, 95% CI 1.7, 9.0). No significant results were observed for 5-9 (n = 111) or >10 (n = 84) bushfire smoke days across pregnancy compared to no bushfire days (n = 288). When separated into trimesters, >10 days of smoke exposure in trimester one was associated with low birth weight (aOR 5.7 95% CI 2.0, 16.4), preterm birth, (aOR 6.3, 95% CI 2.3, 17.7) and NICU admission, aOR 7.2, 95% CI 2.2, 22.8) compared to no days. No significant results were observed for trimesters two or three. Conclusion: Exposure to bushfire smoke during pregnancy in women with asthma, particularly early in pregnancy may be associated with adverse perinatal outcomes.