Maternal exposure to ambient ozone and fetal conotruncal heart defects in China: A multicenter cohort study

The relationships between maternal genetic and environmental exposure and conotruncal heart defects (CTDs) have been extensively investigated. Nevertheless, there is limited knowledge regarding the impact of ozone (O₃) on the risk of CTDs.

To explore the correlation between maternal exposure to O₃ and CTDs in China.

Pregnant women who underwent fetal echocardiography at Beijing Anzhen Hospital between January 2013 and December 2021 were enrolled. Their sociodemographic characteristics and lifestyle information, along with fetal data, were systematically collected. Fetal echocardiography was used to detect CTDs. Maternal exposure to ambient O₃ during the embryonic period, the first trimester, the three months preceding the last menstrual period, and the perinatal period was estimated using residential addresses or hospital addresses associated with prenatal visits. The concentration of O₃ was divided by quartiles, with the first quartile serving as a reference. Adjusted logistic regression models were employed to examine the associations between every 10 μg/m³ increase or quartile increase in ambient O₃ exposure and CTDs.

Among 24,278 subjects, 1069 exhibited fetuses with CTDs. Maternal exposure to ambient O₃ during three pregnancy periods was associated with increased CTD risk. The adjusted odds ratio (OR) and 95% confidence interval (CI) were 1.271 (1.189-1.360) per 10 μg/m³ increase in O₃ during the perinatal period. For each quartile of O_3, the risk increased with increasing exposure concentration, particularly during the perinatal period (OR = 2.206 for quartile 2, 2.367 for quartile 3, and 3.378 for quartile 4, all P<0.05).

Elevated maternal exposure to O₃ during pregnancy, particularly in the perinatal period, is linked to an increased risk of fetal CTDs. Further longitudinal analyses are needed to validate these results.