Acute and chronic effects of ambient fine particulate matter on preterm births in Beijing, China: A time-series model.

Accumulating evidence suggests that short- and long-term exposure to ambient fine particulate matter ≤ 2.5 μm (PM2.5) during pregnancy is associated with preterm births, yet the results are inconsistent, and the shape of the exposure-response curve is unclear, partially due to the limited studies conducted in areas with high air pollution. Our study evaluated the association between ambient PM2.5 concentration and preterm births in Beijing, China.