Short-term exposure to ambient air pollution and emergency ambulance dispatches for precipitous labor: a time-series study in Guangzhou, China

The association between maternal exposure to air pollutants and precipitous labor is still unclear.Emergency ambulance dispatch (EAD) data provide a near real-time, population-wide indicator of acute health exacerbations, enabling the detection of acute population health responses to air quality fluctuations.We examine the relationship between EADs for precipitous labor and short-term exposure to six criteria ambient pollutants using a time-series study. Distributed lag nonlinear models (DLNM) were adopted to explore the impact of air pollutants on precipitous labor emergency ambulance dispatches (PL-EADs) from 2015 to 2024 in Guangzhou, China. In order to clarify the influence of age, season and NDVI greenness on the association, subgroup analysis was carried out. Our findings revealed significant positive associations between short-term exposure to PM2.5, PM10, CO, NO2 and O3 with PL-EADs. NO2 exhibited a statistically significant cumulative lag effect on PL-EADs over the 10-day study period. In the cumulative lag mode, a 10-µg/m3 increase in NO2 was associated with higher risk of precipitous labor with a relative risk of 1.162 (95%CI:1.032,1.309) at lag010.The risk effect of O3 on PL-EADs manifested immediately, followed by a rapid decline. Subgroup analyses revealed that age≥35years, during cold season, and higher NDVI greenness were more susceptible to the adverse impacts of air pollutants. This study provides robust evidence of a significant association between short-term exposure to PM2.5, PM10, CO, NO2 and O3 and PL-EADs.These findings contribute valuable insights into the detrimental effects of air pollution on PL-EADs, which can inform rational allocation and planning of ambulance services.