Associations between neighborhood greenspace and multiple birth outcomes across two metropolitan areas in Australia

The association of adverse birth outcomes with flood exposure before and during pregnancy in Australia: a cohort study

BACKGROUND

Exposure to floods might increase the risks of adverse birth outcomes. However, the current evidence is scarce, inconsistent, and has knowledge gaps. This study aims to estimate the associations of flood exposure before and during pregnancy with adverse birth outcomes and to identify susceptible exposure windows and effect modifiers.

METHODS

In this cohort study, we obtained all the birth records occurring in Greater Sydney, Australia, from Jan 1, 2001, to Dec 31, 2020, from the New South Wales Midwives Data Collection and in the Brisbane metropolitan region, Australia, from Jan 1, 1995, to Dec 31, 2014, from the Queensland Health Perinatal Data Collection. For each birth, residential address and historical flood information from the Dartmouth Flood Observatory were used to estimate the numbers of days with floods during five exposure windows (Pre-1 was defined as 13-24 weeks before the last menstrual period [LMP], Pre-2 was 0-12 weeks before the LMP, trimester 1 [Tri-1] was 0-12 weeks after the LMP, trimester 2 [Tri-2] was 13-28 weeks after the LMP, and trimester 3 [Tri-3] was ≥29 weeks after the LMP). We estimated the hazard ratios (HRs) of adverse birth outcomes (preterm births, stillbirths, term low birthweight [TLBW], and small for gestational age [SGA]) associated with flood exposures in the five exposure windows using Cox proportional hazards regression models.

FINDINGS

1 338 314 birth records were included in our analyses, which included 91 851 (6·9%) preterm births, 9831 (0·7%) stillbirths, 25 567 (1·9%) TLBW, and 108 658 (8·1%) SGA. Flood exposure in Pre-1 was associated with increased risks of TLBW (HR 1·06 [95% CI 1·01-1·12]) and SGA (1·04 [1·01-1·06]); flood exposure during Tri-1 was associated with increased risks of preterm births (1·03 [1·002-1·05]), stillbirth (1·11 [1·03-1·20]), and SGA (1·03 [1·01-1·06]). In contrast, flood exposures during Pre-2 and Tri-3 were associated with reduced risks.

INTERPRETATION

Exposures to floods in Pre-1 and Tri-1 are both associated with increased risks of adverse birth outcomes, and the risks increase with a higher exposure. Upon planning for conception and prenatal care, individuals and health practitioners should raise awareness of the increased risks of adverse birth outcomes after experiencing floods.

FUNDING

The Australian Research Council and the Australian National Health and Medical Research Council.

Joint effects of green space and air pollutant exposure on preterm birth: evidence from a nationwide study in China

An association between green space exposure and preterm birth has been reported. However, evidence on the joint effects of air pollutant and green space exposure on preterm birth from nationwide research is limited in China. Based on a nationwide cohort, this study aims to explore the effect of green space exposure on preterm birth and analyze the joint effects of green space and air pollutant. Logistic regression models were developed to analyze the effects of green space exposure, and interaction effects were evaluated by adding interaction terms between green space and air pollutants. From 2013 to 2019, this study included 2,294,188 records of newborn births, of which 82,921 were preterm births. The results show that for buffer zones with 250 m, 500 m, 1000 m, and 1500 m, every 0.1 unit increase in NDVI exposure was associated with a decrease in the risk of preterm birth by 5.5% (95% CI: 4.6-6.4%), 5.8% (95% CI: 4.9-6.6%), 6.1% (95% CI: 5.3-7.0%), and 5.6% (95% CI: 4.7-6.5%), respectively. Under high-level exposure to air pollutants, high-level NDVI exposure was more strongly negatively correlated with preterm birth than low-level NDVI exposure. High-level green space exposure might mitigate the adverse effect of air pollutants on preterm birth by promoting physical activity, reducing stress, and adsorbing pollutants. Further investigation is needed to explore how green space and air pollution interact and affect preterm birth, in order to improve risk management and provide a reference for newborn health.

Heat Exposure, Preterm Birth, and the Role of Greenness in Australia

Importance

Preterm birth (PTB) is associated with adverse health outcomes. The outcomes of heat exposure during pregnancy and the moderating association of greenness with PTB remain understudied.

Objective

To investigate associations between heat exposure, greenness, and PTB, as well as interactions between these factors.

Design, Setting, and Participants

Included in this cohort study were births occurring in Sydney, New South Wales, Australia, between 2000 and 2020, retrieved from New South Wales Midwives Data Collection. Participants with incomplete or missing data on their residential address or those who resided outside of New South Wales during their pregnancy were excluded. Data were analyzed from March to October 2023.

Exposures

Greenness measured using normalized difference vegetation index (NDVI) and tree cover derived from satellite images. Daily extreme heat and nighttime extreme heat were defined as above the 95th percentile of community- and trimester-specific daily mean temperatures and nighttime temperatures.

Main Outcomes and Measures

Logistic regression models estimated the independent association of extreme heat with PTB, adjusting for individual- and area-level covariates, season of conception, and long-term trend. An interaction term between extreme heat exposure and greenness was included to explore potential modification. With a significant interaction observed, the number of preventable heat-associated PTBs that were associated with greenness was estimated.

Results

A total of 1 225 722 births (median [IQR] age, 39 [38-40] weeks; 631 005 male [51.5%]) were included in the analysis, including 63 144 PTBs (median [IQR] age, 35 [34-36] weeks; 34 822 male [55.1%]). Compared with those without heat exposure, exposure to daily extreme heat and nighttime extreme heat in the third trimester was associated with increased risks of PTB, with an adjusted odds ratio (OR) of 1.61 (95% CI, 1.55-1.67) and 1.51 (95% CI, 1.46-1.56]), respectively (PTB rates: exposed, 4615 of 61 338 [7.5%] vs unexposed, 56 440 of 1 162 295 [4.9%] for daily extreme heat and 4332 of 61 337 [7.1%] vs 56 723 of 1 162 296 [4.9%] for nighttime extreme heat). Disparities in associations between extreme heat exposure and PTB were observed, with lower odds of PTB among pregnant individuals residing in greener areas. The associations between extreme heat exposure and PTB could be mitigated significantly by higher greenness. Improving NDVI and tree cover could reduce daily extreme heat-associated PTB by 13.7% (95% CI, 2.3%-15.1%) and 20.9% (95% CI, 5.8%-31.5%), respectively. For nighttime extreme heat-associated PTB, reductions were 13.0% (0.2%-15.4%) and 17.2% (4.1%-27.0%), respectively.

Conclusions and Relevance

Results of this large birth cohort study suggest that extreme heat exposure was adversely associated with PTB, with greenness playing a moderating role. Increasing greenness levels in residential communities could prevent heat-associated PTBs. These findings emphasize the importance of integrating heat mitigation strategies and improving green space in urban planning and public health interventions.

Maternal greenness exposure and preterm birth in Brazil: A nationwide birth cohort study

In the dynamic landscape of maternal and child health, understanding the intricate interplay between environmental factors and pregnancy outcomes is of paramount importance. This study investigates the relationship between maternal greenness exposure and preterm births in Brazil using data spanning from 2010 to 2019. Satellite-derived indices, including the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), were employed to assess greenness exposure during whole pregnancy in maternal residential area. Employing Cox proportional hazard models, we calculated the hazard ratios (HRs) with 95% confidence intervals (CIs) for changes in NDVI, while adjusting for individual and area-level covariates. In total, 24,010,250 live births were included. Prevalence of preterm birth was 11.5%, with a modest but statistically significant decreasing trend (p = 0.013) observed across the nation over the study period. The findings reveal a significant association between greenness exposure and a reduced risk of preterm birth. Specifically, for every 0.1 increase in NDVI, there was a 2.0% decrease in the risk of preterm birth (95%CI: 1.9%-2.2%). Stratified analyses based on maternal education and ethnicity indicated potential effect modifications, with stronger protective effects observed among younger mothers and those with less years of education. Sensitivity analyses using EVI yielded consistent results. In conclusion, this study suggests that higher maternal greenness exposure is linked to a decreased risk of preterm birth in Brazil. These findings imply that enhancing residential greenspaces could be a valuable public health strategy to promote maternal and child health in Brazil.