Disease burden of gestational complications associated with ozone pollution in the Yangtze River Delta region

Background In recent years, ozone (O₃) has gradually become a key air pollutant affecting public health. Studies have been conducted to evaluate O₃ pollution-associated disease burden for general population, but there is a lack of research on O₃ pollution-associated disease burden of gestational complications.

Objective To assess the disease burden of O₃ pollution on pregnancy complications in the Yangtze River Delta region and the changes in the disease burden resulting from the improvement of O₃ pollution levels.

Methods Through Chinese databases such as China National Knowledge Infrastructure (CNKI) and Wanfang, as well as English databases including PubMed and Web of Science, a systematic search was conducted to retrieve epidemiological studies investigating the association between O₃ exposure and pregnancy complications from January 1, 2010 to February 28, 2023. Using predetermined inclusion and exclusion criteria, retrieved studies were screened and assessed for heterogeneity using the Higgins I² statistic. The exposure increment was standardized to 10 µg·m⁻³, and a meta-analysis was conducted to evaluate the exposure-response relationship. Spatial analysis and environmental health risk assessment were then employed, using O₃ monitoring data at national air monitoring stations, population data, and related disease burden parameters in the Yangtze River Delta region, to evaluate changes in the disease burden of pregnancy complications associated with improvements in O₃ pollution levels.

Results The meta-analysis revealed a significant association between maternal O₃ exposure and increased risks of gestational diabetes mellitus (GDM) and hypertensive disorders of pregnancy (HDP), particularly in early pregnancy, and the related odds ratios (OR) and 95% confidence intervals (CI) were 1.028 (1.002, 1.055) and 1.031 (1.023, 1.040), respectively. The cities with higher attribution fractions (AF) of GDM and HDP related to O₃ exposure in 2017 and 2020 in the Yangtze River Delta region were Xuzhou, Huaibei, Suzhou (Anhui Province), Changzhou, and Wuxi, with most cities showing a significant decrease in AF in 2020. Except for Hefei, the cases of GDM and HDP attributable to O₃ exposure in the remaining cities of the Yangtze River Delta region decreased by 16.31% to 57.41% in 2020 compared to 2017. In addition, except for Hefei, Suqian, Anqing, and Wuxi, the direct medical costs attributed to O₃ exposure in the remaining cities decreased by 1.12% to 45.36% in 2020 compared to 2017.

Conclusion Exposure to O₃ during pregnancy is associated with increased risks of GDM and HDP. There are differences in the disease burden of GDM and HDP related to O₃ pollution among cities in the Yangtze River Delta region in 2017 and 2020. In 2020, compared to 2017, the disease burden in most cities is decreased.