Abstract：
BACKGROUND: Nationwide evidence linking maternal ozone exposure with fetal growth restriction (FGR) was extensively scarce, especially in the Middle East with dry climate and distinct religious culture.
METHODS: We carried out a national retrospective birth cohort study using registry-based records from 749 hospitals across 31 provinces in Iran from 2013 to 2018. Monthly concentrations of maximum daily average 8-hour (MDA8) ozone at 0.125° × 0.125° resolution were extracted from well-validated spatiotemporal grid dataset. Linear and logistic regression models were employed to evaluate associations of maternal MDA8 ozone exposure with birthweight outcomes. Assuming causality, the comparative risk assessment framework was utilized to estimate the burden of low birthweight (LBW), small for gestational age (SGA), and birthweight loss per livebirth (BLL) attributable to ambient ozone pollution.
RESULTS: Of 4030383 livebirths included in the study, 264304 (6.6%) were LBW and 484405 (12.0%) were SGA. Each 10-ppb increase in MDA8 ozone exposure was associated with an odds ratio of 1.123 (95% confidence interval [CI]: 1.104 to 1.142) for LBW and 1.210 (95% CI: 1.197 to 1.223) for SGA, and a 30.5-g (95% CI: 29.0 to 32.0) reduction in birthweight. We observed approximately linear exposure-response relationships of maternal MDA8 ozone exposure with LBW (Pnonlinear= 0.786), SGA (Pnonlinear= 0.156), and birthweight reduction (Pnonlinear= 0.104). Under the premise of causal association, we estimated 6.6% (95% CI: 5.7 to 7.5) of LBW, 10.1% (95% CI: 9.6 to 10.6) of SGA, and 18.8 g (95% CI: 17.9 to 19.7) of BLL could be attributable to maternal ozone exposure in Iran. Considerably greater risk and burden of ozone-related FGR were observed among younger, less-educated, and rural-dwelling mothers.
CONCLUSIONS: Our study provided compelling evidence that maternal ozone exposure was associated with heightened FGR risk and burden, particularly among socioeconomically disadvantaged mothers. These findings underscored the urgent need for government to incorporate socioeconomic factors into future ozone-related health policies, not only to mitigate pollution, but also minimize inequality.
METHODS: We carried out a national retrospective birth cohort study using registry-based records from 749 hospitals across 31 provinces in Iran from 2013 to 2018. Monthly concentrations of maximum daily average 8-hour (MDA8) ozone at 0.125° × 0.125° resolution were extracted from well-validated spatiotemporal grid dataset. Linear and logistic regression models were employed to evaluate associations of maternal MDA8 ozone exposure with birthweight outcomes. Assuming causality, the comparative risk assessment framework was utilized to estimate the burden of low birthweight (LBW), small for gestational age (SGA), and birthweight loss per livebirth (BLL) attributable to ambient ozone pollution.
RESULTS: Of 4030383 livebirths included in the study, 264304 (6.6%) were LBW and 484405 (12.0%) were SGA. Each 10-ppb increase in MDA8 ozone exposure was associated with an odds ratio of 1.123 (95% confidence interval [CI]: 1.104 to 1.142) for LBW and 1.210 (95% CI: 1.197 to 1.223) for SGA, and a 30.5-g (95% CI: 29.0 to 32.0) reduction in birthweight. We observed approximately linear exposure-response relationships of maternal MDA8 ozone exposure with LBW (Pnonlinear= 0.786), SGA (Pnonlinear= 0.156), and birthweight reduction (Pnonlinear= 0.104). Under the premise of causal association, we estimated 6.6% (95% CI: 5.7 to 7.5) of LBW, 10.1% (95% CI: 9.6 to 10.6) of SGA, and 18.8 g (95% CI: 17.9 to 19.7) of BLL could be attributable to maternal ozone exposure in Iran. Considerably greater risk and burden of ozone-related FGR were observed among younger, less-educated, and rural-dwelling mothers.
CONCLUSIONS: Our study provided compelling evidence that maternal ozone exposure was associated with heightened FGR risk and burden, particularly among socioeconomically disadvantaged mothers. These findings underscored the urgent need for government to incorporate socioeconomic factors into future ozone-related health policies, not only to mitigate pollution, but also minimize inequality.
摘要：
背景：全国范围内将母体臭氧暴露与胎儿生长受限（FGR）联系起来的证据非常缺乏，特别是在中东，气候干燥，宗教文化鲜明。
方法：我们使用2013年至2018年伊朗31个省749家医院的注册记录进行了一项全国回顾性出生队列研究。从经过充分验证的时空网格数据集中提取了0.125°×0.125°分辨率下最大日平均8小时（MDA8）臭氧的月浓度。线性和逻辑回归模型用于评估母亲MDA8臭氧暴露与出生体重结局的关联。假设因果关系，比较风险评估框架用于估计低出生体重(LBW)的负担，小于胎龄（SGA），和可归因于环境臭氧污染的每次分娩体重减轻(BLL)。
结果：在研究中纳入的4030383例分娩中，264304(6.6%)为LBW,484405(12.0%)为SGA。MDA8臭氧暴露每增加10ppb，LBW的比值比为1.123（95％置信区间[CI]：1.104至1.142），SGA的比值比为1.210（95％CI：1.197至1.223），出生体重减轻30.5g（95％CI：29.0至32.0）。我们观察到母体MDA8臭氧暴露与LBW的近似线性暴露-响应关系（Pnronic=0.786），SGA（P非线性=0.156），和出生体重减少(Pnronic=0.104)。在因果关联的前提下,我们估计6.6%(95%CI：5.7至7.5)的LBW，10.1%（95%CI：9.6至10.6）的SGA，18.8g(95%CI:17.9-19.7)BLL可能归因于伊朗的母体臭氧暴露。在年轻人中观察到与臭氧相关的FGR的风险和负担相当大，受教育程度较低,和农村居住的母亲。
结论：我们的研究提供了令人信服的证据，表明母体臭氧暴露与FGR风险和负担增加有关。特别是在社会经济上处于不利地位的母亲中。这些发现强调了政府迫切需要将社会经济因素纳入未来与臭氧有关的卫生政策，不仅是为了减轻污染，但也尽量减少不平等。
方法：我们使用2013年至2018年伊朗31个省749家医院的注册记录进行了一项全国回顾性出生队列研究。从经过充分验证的时空网格数据集中提取了0.125°×0.125°分辨率下最大日平均8小时（MDA8）臭氧的月浓度。线性和逻辑回归模型用于评估母亲MDA8臭氧暴露与出生体重结局的关联。假设因果关系，比较风险评估框架用于估计低出生体重(LBW)的负担，小于胎龄（SGA），和可归因于环境臭氧污染的每次分娩体重减轻(BLL)。
结果：在研究中纳入的4030383例分娩中，264304(6.6%)为LBW,484405(12.0%)为SGA。MDA8臭氧暴露每增加10ppb，LBW的比值比为1.123（95％置信区间[CI]：1.104至1.142），SGA的比值比为1.210（95％CI：1.197至1.223），出生体重减轻30.5g（95％CI：29.0至32.0）。我们观察到母体MDA8臭氧暴露与LBW的近似线性暴露-响应关系（Pnronic=0.786），SGA（P非线性=0.156），和出生体重减少(Pnronic=0.104)。在因果关联的前提下,我们估计6.6%(95%CI：5.7至7.5)的LBW，10.1%（95%CI：9.6至10.6）的SGA，18.8g(95%CI:17.9-19.7)BLL可能归因于伊朗的母体臭氧暴露。在年轻人中观察到与臭氧相关的FGR的风险和负担相当大，受教育程度较低,和农村居住的母亲。
结论：我们的研究提供了令人信服的证据，表明母体臭氧暴露与FGR风险和负担增加有关。特别是在社会经济上处于不利地位的母亲中。这些发现强调了政府迫切需要将社会经济因素纳入未来与臭氧有关的卫生政策，不仅是为了减轻污染，但也尽量减少不平等。
