Dr Bronwyn Brew

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 <2.5 µm in diameter (PM2.5) 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.

Background: Food allergy has been shown to negatively impact children's mental health and quality of life. However, its impact on school performance is unknown. Objective: We aimed to investigate whether food allergy, severe and nonsevere, is associated with school performance when accounting for measured and unmeasured familial factors. Methods: This was a register-based cohort study, with sibling controls, including all children born in Sweden 2001-5 (n = 456,164) with food allergy information based on hospital visits and prescriptions, grades, and national test results from all Swedish schools and confounders. Primary exposure was food allergy severity (none, nonsevere, or severe) in school years 7-9, and the primary outcome was total grades from year 9, with secondary exposures/outcomes also at younger ages. The primary outcome was analyzed by linear regression and, for sibling/twin control analyses, fixed effect linear regression. Results were replicated in a twin cohort (n = 31,609). Results: In unadjusted and analyses adjusted for measured confounders, children with severe food allergy appeared to have better total grades than children without food allergy (ßunadjusted = 10.6 [95% confidence interval (CI), 8.6, 12.6] and ßadjusted = 5.5 [95% CI, 3.7, 7.4]). When also adjusting for unmeasured confounders shared by siblings, the difference was close to null and statistically nonsignificant (ßsibling = 1.6 [95% CI, -1.5, 4.7]; for nonsevere food allergy, ßsibling = -0.0 [95% CI, -2.2, 2.1]). The twin cohort results were similar. Conclusions: We found no consistent evidence of a negative effect of food allergy, either severe or nonsevere, on school performance when adjusting for measured and unmeasured confounders shared by siblings.

Background Both depression and respiratory disease are common today in young populations. However, little is known about the relationship between them. Aims This study aims to explore the association between depression in childhood to early adulthood and respiratory health outcomes in early adulthood, and the potential underlying mechanisms. Method A prospective study was conducted based on the Swedish BAMSE (Barn, Allergi, Miljö, Stockholm, Epidemiologi [Children, Allergy, Milieu, Stockholm, Epidemiology]) birth cohort (n = 4089). We identified clinically diagnosed depression through the dispensation of antidepressants, using national register data confirmed by self-reported diagnosis. At the 24-year follow-up, respiratory health was assessed via questionnaires and clinical evaluation. Metabolic and inflammatory profiles were analysed to explore potential mechanisms. Results Among the 2994 participants who provided study data, 403 (13.5%) had depression at any time point from around age 10 to 25 years. Depression was associated with higher risks of any chronic bronchitis symptoms (odds ratio = 1.58, 95% CI 1.21¿2.06) and respiratory symptoms (odds ratio = 1.41, 95% CI 1.11¿1.80) in early adulthood, independent of body mass index (BMI) and smoking status. Compared to individuals without depression, those with depression had a higher fat mass index (FMI (ß = 0.48, 95% CI 0.22¿0.74)) and increased blood levels of fibroblast growth factor 21 and Interleukin-6 in early adulthood. These markers together with FMI were found to partly mediate the association between depression and respiratory symptoms (total mediation proportion: 19.8 and 15.4%, respectively, P < 0.01). Conclusions Depression in childhood to early adulthood was associated with an increased risk of respiratory ill-health in early adulthood, independently of smoking. Metabolic and inflammatory dysregulations may underlie this link.

Introduction To investigate the association between maternal depression/anxiety during pregnancy and offspring type 1 diabetes, to assess the specific importance of exposure during pregnancy by comparing across different exposure periods before and/or after pregnancy, and to explore potential unmeasured familial confounding. Research design and methods This was a population-based cohort including 1 807 809 offspring born in Sweden 2002-2019. From national registers, data were available on diagnosis or medication prescription for depression/anxiety in and around pregnancy, as well as incident cases of type 1 diabetes defined through diagnosis or insulin treatment. Associations were examined using flexible parametric and Cox regression models. Familial confounding was explored using paternal exposure as a negative control and by comparing offspring exposed to maternal depression/anxiety with their unexposed siblings. Results For exposure during pregnancy, maternal depression/anxiety was associated with an increased risk of offspring type 1 diabetes onset after, but not before, 8 years of age (adjusted HR (aHR) 1.21 (95% CI 1.03 to 1.42]). Exposure occurring only during pregnancy was similarly associated to type 1 diabetes (aHR 1.24 (0.96 to 1.60)), whereas exposure occurring only before pregnancy was not (aHR 0.91 (0.64 to 1.30)). Associations were close to the null for paternal depression/anxiety (aHR 0.95 (0.72 to 1.25)), and point estimates were above 1 in sibling comparisons, although with wide CIs (aHR 1.36 (0.82 to 2.26)). Conclusions Maternal depression/anxiety specifically during pregnancy seems to be associated with offspring type 1 diabetes. Paternal negative control and sibling comparisons indicate that the results cannot entirely be explained by familial confounding.

Landscape fires are increasing in frequency and severity globally. In Australia, extreme bushfires cause a large and increasing health and socioeconomic burden for communities and governments. People with asthma are particularly vulnerable to the effects of landscape fire smoke (LFS) exposure. Here, we present a position statement from the Thoracic Society of Australia and New Zealand. Within this statement we provide a review of the impact of LFS on adults and children with asthma, highlighting the greater impact of LFS on vulnerable groups, particularly older people, pregnant women and Aboriginal and Torres Strait Islander peoples. We also highlight the development of asthma on the background of risk factors (smoking, occupation and atopy). Within this document we present advice for asthma management, smoke mitigation strategies and access to air quality information, that should be implemented during periods of LFS. We promote clinician awareness, and the implementation of public health messaging and preparation, especially for people with asthma.

Introduction: Gastro-oesophageal reflux disease (GERD) is the most common non-allergic comorbidity in adults with asthma; however, comorbidity with other atopic diseases such as eczema and hay fever is unclear. The objective was to assess the comorbidity of GERD with asthma and atopic diseases and to investigate possible mechanisms, including genetic and/or affective factors. Methods: A co-twin control study harnessing 46 583 adult twins. Questionnaires on health status were linked to national patient and prescribed drug register data. Analyses tested associations of comorbidity between multiple definitions of atopic diseases (self-report and register-based) with GERD. Comparisons were made between unpaired, monozygotic (MZ) and dizygotic (DZ) twins to assess genetic liability. Affective traits (depression, anxiety and neuroticism) were added to models as possible explanatory factors. Results: The risk of GERD in those with asthma was OR (odds ratio) 1.52 (95% CI 1.38, 1.68), hay fever OR 1.22 (95%CI 1.12, 1.34) and eczema OR 1.23 (95%CI 1.10, 1.38). Adjusting for affective traits completely attenuated the comorbidity associations for hay fever and eczema with GERD, and partly for asthma with GERD. Co-twin control associations attenuated suggesting a shared cause for both GERD and atopic diseases. For example, all twins adjOR 1.32 (95%CI 1.00, 1.74), 0.97 (95% CI 0.76¿1.23) and 1.11 (95%CI 0.85¿1.45) for self-report asthma, hay fever and eczema with GERD respectively. Conclusions: GERD is a common comorbidity in adults with asthma, hay fever and/or eczema. We found evidence for shared mechanisms suggesting common underlying causes that may involve affective traits requiring further investigation.

Background: From November 2019 to January 2020, eastern Australia experienced the worst bushfires in recorded history. Two months later, Sydney and surrounds were placed into lockdown for six weeks due to the COVID-19 pandemic, followed by ongoing restrictions. Many pregnant women at this time were exposed to both the bushfires and COVID-19 restrictions. Objective: To assess the impact of exposure to bushfires and pandemic restrictions on perinatal outcomes. Methods: The study included 60 054 pregnant women who gave birth between November 2017 and December 2020 in South Sydney. Exposure cohorts were based on conception and birthing dates: 1) bushfire late pregnancy, born before lockdown; 2) bushfires in early-mid pregnancy, born during lockdown or soon after; 3) conceived during bushfires, lockdown in second trimester; 4) conceived after bushfires, pregnancy during restrictions. Exposure cohorts were compared with pregnancies in the matching periods in the two years prior. Associations between exposure cohorts and gestational diabetes, preeclampsia, hypertension, stillbirth, mode of birth, birthweight, preterm birth and small for gestational age were assessed using generalised estimating equations, adjusting for covariates. Results: A decrease in low birth weight was observed for cohort 1 (aOR 0.81, 95%CI 0.69, 0.95). Conversely, cohort 2 showed an increase in low birth weight, and increases in prelabour rupture of membranes, and caesarean sections (aOR 1.18, 95%CI 1.03, 1.37; aOR 1.21, 95%CI 1.07, 1.37; aOR 1.10 (1.02, 1.18) respectively). Cohort 3 showed an increase in unplanned caesarean sections and high birth weight babies (aOR 1.15, 95%CI 1.04, 1.27 and aOR 1.16, 95%CI 1.02, 1.31 respectively), and a decrease in gestational diabetes mellitus was observed for both cohorts 3 and 4. Conclusion: Pregnancies exposed to both severe climate events and pandemic disruptions appear to have increased risk of adverse perinatal outcomes beyond only experiencing one event, but further research is needed.

Background: We aimed to study whether pre-eclampsia is associated with childhood asthma, allergic and non-Allergic asthma, accounting for family factors and intermediate variables. Methods: The study population comprised 779 711 children born in 2005-2012, identified from Swedish national health registers (n = 14 823/7410 exposed to mild/moderate and severe pre-eclampsia, respectively). We used Cox regression to estimate the associations of mild/moderate and severe pre-eclampsia with incident asthma, before and after age 2 years. Cox regressions were controlled for familial factors using sibling comparisons, then stratified on high and low risk for intermediate variables: caesarean section, prematurity and small for gestational age. We used logistic regression for allergic and non-Allergic prevalent asthma at 6 years as a measure of more established asthma. Results: The incidence of asthma in children was 7.7% (n = 60 239). The associations varied from adjusted hazard ratio (adjHR) 1.11, 95% confidence interval (CI): 1.00, 1.24 for mild/moderate pre-eclampsia and asthma at >2 years age, to adjHR 1.78, 95% CI: 1.64, 1.95 for severe pre-eclampsia and asthma at <2 years age. Sibling comparisons attenuated most estimates except for the association between severe pre-eclampsia and asthma at <2 years age (adjHR 1.45, 95% CI: 1.10, 1.90), which also remained when stratifying for the risk of intermediates. Mild/moderate and severe pre-eclampsia were associated with prevalent non-Allergic (but not allergic) asthma at 6 years, with adjusted odds ratio (adjOR) 1.17, 95% CI: 1.00, 1.36 and adjOR 1.51, 95% CI: 1.23, 1.84, respectively. Conclusions: We found evidence that severe, but not mild/moderate, pre-eclampsia is associated with asthma regardless of familial factors and confounders.

Background Australia has one of the highest rates of asthma worldwide. Indigenous children have a particularly high burden of risk determinants for asthma, yet little is known about the asthma risk profile in this population. Aim To identify and quantify potentially preventable risk factors for hospitalised asthma in Australian Aboriginal children (1-4 years of age). Methods Birth, hospital and emergency data for all Aboriginal children born 2003-2012 in Western Australia were linked (n=32 333). Asthma was identified from hospitalisation codes. ORs and population attributable fractions were calculated for maternal age at birth, remoteness, area-level disadvantage, prematurity, low birth weight, maternal smoking in pregnancy, mode of delivery, maternal trauma and hospitalisations for acute respiratory tract infection (ARTI) in the first year of life. Results There were 705 (2.7%) children hospitalised at least once for asthma. Risk factors associated with asthma included: being hospitalised for an ARTI (OR 4.06, 95% CI 3.44 to 4.78), area-level disadvantage (OR 1.58, 95% CI 1.28 to 1.94), being born at <33 weeks' gestation (OR 3.30, 95% CI 2.52 to 4.32) or birth weight <1500 g (OR 2.35, 95% CI 1.39 to 3.99). The proportion of asthma attributable to an ARTI was 31%, area-level disadvantage 18%, maternal smoking 5%, and low gestational age and birth weight were 3%-7%. We did not observe a higher risk of asthma in those children who were from remote areas. Conclusion Improving care for pregnant Aboriginal women as well as for Aboriginal infants with ARTI may help reduce the burden of asthma in the Indigenous population.

Background: As research focuses on the concept of resilience, evidence suggests that greater levels of personal hope may have a mitigating effect on the mental health impact of adversity. In view of the adversity affecting rural communities, a better understanding of factors influencing personal hope may help identify foci for mental health promotion and mental illness prevention research and interventions. Aim: To explore the relationship between demographic, socioeconomic and mental health factors and personal hopefulness, including the influence of locality and remoteness. Method: Using data from two community-based longitudinal cohorts from New SouthWales ¿ one urban and one rural ¿ we analysed cross-sectional relationships between a range of factors and personal hopefulness using logistic regression techniques, as part of a common follow-up. Personal hopefulness was measured using a 12-item scale and scores were categorised as low (<2.5), medium (2.5¿3.4) and high (=3.5). Results: Of 2774 participants (53% female, mean age 69.1 years [SD 7.3, range 58¿91 years], 36% living outside metropolitan areas) 32% had low, 51% had medium and 17% had high personal hopefulness scores. Several factors displayed univariate associations with personal hopefulness. In the multivariate model, five factors were independently associated with lower personal hopefulness: being older, having lower perceived prosperity, less frequent socialisation, experiencing high psychological distress or psychological impairment. Hopefulness was not associated with geographical location. Conclusion: The impact of current psychological distress and aspects of adversity on personal hopefulness over time should be further investigated in longitudinal research. Personal hopefulness did not differ across geographical location.