Maternal ambient air pollution exposure and risk of stillbirth in Georgia, USA

Maternal ambient air pollution exposure and risk of stillbirth in Georgia, USA

Time-varying ambient air pollution exposures during pregnancy were associated with an increased risk of stillbirth, particularly for second-trimester exposures and for stillbirths occurring earlier in pregnancy, highlighting the importance of considering gestational timing when evaluating environmental risk factors for stillbirth.

Acute associations between ambient air pollution and risks of preterm and early-term births: results from 8 states in the United States

Early-pregnancy exposure to air pollution and stillbirth in São Paulo, Brazil – results from the FetRisks case-control study

Stillbirth remains a major public health concern, particularly in urban settings with persistent air pollution, while evidence remains limited in middle-income countries. This study aims to examine the association between prenatal exposure to fine particulate matter (PM2.5) PM2.5 and stillbirth in São Paulo, Brazil. Case-control study including 348 antepartum stillbirths and 419 live births recruited from 14 public hospitals. PM2.5 exposure was estimated using residential addresses linked to the nearest air quality monitoring station. We evaluated median PM2.5 levels during the first trimester of pregnancy and sustained higher PM2.5 exposure episodes (> 12.7 µg/m³ for ≥ 3 weeks). We explored the interaction between air pollution and maternal factors. Multiple logistic regression models were adjusted for maternal sociodemographics. All participants were exposed to PM2.5 concentrations substantially above the WHO Air Quality Guidelines. Sustained higher PM2.5 exposure was associated with higher odds of stillbirth (ORadj 1.51; 95% CI: 1.03–2.25) and showed a significant interaction with maternal age ≥ 35 years, increasing the odds of having a stillbirth (ratio of ORadj 2.55 [95% CI: 1.08–6.23]). Stillbirth was associated with episodes of sustained higher PM2.5 exposure in early pregnancy, in a context where all women experienced high pollutant levels. The coexistence of high baseline PM2.5 exposure and multiple maternal vulnerabilities underscore the need for integrated strategies addressing air quality, health equity, and perinatal care to reduce preventable stillbirths in highly polluted urban environments. Sustained higher PM2.5 exposure in early pregnancy increased stillbirth risk in São Paulo. All participants were exposed to PM2.5 levels above the WHO AQG 2021. Air pollution’s effect on stillbirth was higher among women with advanced age. Findings support urgent air quality improvements and integrated maternal–environmental health policies.

Estimating the risk and burden of stillbirth related to prenatal nitrogen dioxide exposure in a birth cohort of 3.98 million mother-baby pairs.

Despite mounting evidence linking ambient air pollution to adverse birth outcomes, the nexus between stillbirth risk and prenatal nitrogen dioxide (NO2) exposure remains limited and inconsistent, particularly in low- and middle-income countries (LMICs). We examined 3982304 mother-infant pairs recorded in Iran during 2013-2018. Pregnancy-average NO2 concentrations were assigned using satellite-based gridded estimates averaged within 10-km buffers around delivery hospitals. Logistic regression models were fitted in single-, bi-, and tri-pollutant frameworks, with analyses conducted in parallel under the Iranian (≥ 22 gestational weeks) and WHO (≥ 28 gestational weeks) stillbirth definitions. In the single-pollutant model, per 10-μg/m3 increase in prenatal NO2 was associated with an elevated stillbirth odds of 1.206 (95% confidence interval: 1.192, 1.220) under the Iranian definition and 1.106 (1.088, 1.125) under the WHO definition. Co-pollutant analyses estimated generally unchanged associations after adjustment of PM2.5 or/and ozone. In both stillbirth definitions, we observed a monotonic increasing exposure-response function, with stronger associations at lower NO2 concentrations. Assuming causality, achieving an annual NO2 concentration of 10 μg/m3 was associated with 7686 (7242, 8127) potentially avoidable stillbirths under the Iranian definition and 2114 (1780, 2445) under the WHO definition, corresponding to attributable fractions of 25.8% (24.3%, 27.3%) and 14.0% (11.8%, 16.2%), respectively. Associations were stronger among mothers with lower educational attainment, whereas attributable burdens were larger among urban and highly educated mothers because of higher exposure levels. This study provides nationwide cohort evidence for increased risk of stillbirth associated with prenatal NO2 exposure, emphasizing the potential for stricter air quality regulations to reduce the stillbirth burden, particularly in LMICs.

Industrial emissions and risks of preterm and small-for-gestational-age birth: A population-based cohort study in Quebec, Canada

Background: Ambient air pollution has been linked to adverse birth outcomes, but the role of industrial emissions remains understudied. We examined the association between maternal exposure to industrial air pollutants during pregnancy and the risk of preterm birth (PTB) and small-for-gestational-age (SGA) birth. Methods: We conducted a retrospective cohort study of 1,199,516 singleton live births in Quebec, Canada, from 2002 to 2016. Exposure to PM2.5, NO2, and SO2 emitted by industries within 7.5 km of the maternal residence was estimated using an indicator combining residential proximity, emissions, and wind data. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for PTB and SGA comparing exposed to unexposed individuals. We assessed the modifying effects of maternal comorbidities using subgroup analyses. Results: The cohort comprised 71,699 PTB and 105,894 SGA cases. Compared with unexposed participants, exposure to industrial air pollutants during pregnancy increased the risk of extreme and very PTB and SGA. For extreme PTB, adjusted ORs (95% CI) comparing exposed with unexposed were 1.08 (1.00, 1.17) for PM2.5, 1.11 (1.03, 1.19) for NO2, and 1.05 (0.98, 1.12) for SO2. For SGA, the corresponding values were 1.03 (1.02, 1.05) for PM2.5, 1.03 (1.02, 1.04) for NO2, and 1.05 (1.04, 1.06) for SO2. Exposure to NO2 was associated with a higher risk of extreme and very PTB among mothers with preeclampsia (OR: 1.26; 95% CI: 1.12, 1.42) compared with no preeclampsia (OR:1.07; 95% CI: 1.01, 1.12). Conclusion: Exposure to industrial air emissions during pregnancy may increase the risk of extreme and very PTB and SGA, especially among women with preeclampsia.

Associations of Prenatal BTEX Exposure with Preterm Birth: A Nationwide Birth Cohort Study in 337 Chinese Cities.

Long-term exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) has been linked to preterm birth (PTB), yet evidence from China remains limited. This study included 4,321,599 live singleton births from the National Free Preconception Health Examination Project between 2010 and 2015. Prenatal BTEX exposure was estimated using a chemistry-climate model. Multivariate linear regression and logistic regression models were applied to examine associations of BTEX exposure with gestational age and PTB risk, respectively. For the entire pregnancy, each interquartile range (IQR, 11.6 μg/m3) increase in BTEX exposure was associated with a reduction of 0.138 (95% confidence interval [CI]: 0.133-0.142) weeks in gestational age and a 23% (odds ratio [OR]: 1.23, 95% CI: 1.22-1.24) increase in PTB risk. Among individual components, IQR increases in benzene, toluene, and xylenes concentrations were associated with 21% (95% CI: 20-22%), 25% (95% CI: 24-26%), and 20% (95% CI: 19-21%) higher odds of PTB, respectively. The strongest associations were observed for exposures during the third trimester for both BTEX (OR = 1.27, 95% CI: 1.26-1.28) and individual components (benzene: OR = 1.25, 95% CI: 1.24-1.26; toluene: OR = 1.29, 95% CI: 1.28-1.30; and xylenes: OR = 1.25, 95% CI: 1.24-1.26). Subgroup analyses indicated that the associations were more pronounced among male fetuses, mothers who were overweight or obese, engaged in farming, or had lower educational attainment. Prenatal BTEX exposure was significantly associated with an elevated risk of PTB, emphasizing the potential adverse effects of BTEX pollution on maternal and infant health.