Figure 1.

Associations of extreme climate events with the preterm birth in China Labor and Delivery Survey ($n=\mathrm{70,818}$). Note: Generalized linear mixed model was used to examine the associations. ORs represent a 1-unit increase in extreme weather events and are presented with a 95% CI. All models were adjusted for maternal age, maternal ethnicity, maternal education, insurance type, child sex, parity, GDP per capita, geographic region, conception season, conception year, ${\mathrm{PM}}_{2.5}$, and ${\mathrm{O}}_3$. CI, confidence interval; GDP, gross domestic product; OR, odds ratio; ${\mathrm{PM}}_{2.5}$, particulate matter with aerodynamic diameter $\le 2.5\mathrm{\mu }\mathrm{m}$.