Objective   To analyze the incidence rate of adverse pregnancy outcomes in Jinchang and Zhangye city of Gansu province and to explore possible factors related to adverse pregnancy outcomes.

  Methods   We collected all records of hospitalized deliveries in 5 hospitals and data on concentrations of main air pollutants in Jinchang and Zhangye city of Gansu province from January 2007 to December 2014. The association of ambient air quality with the incidence of adverse pregnancy outcome was analyzed using SPSS 22.0.

  Results   The concentration of sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and particulate matter less the 10 μm in aerodynamic diameter (PM₁₀) in Jinchang city were higher than those in Zhangye city but there was no obvious difference in the concentration of particulate matter less the 2.5 μm in aerodynamic diameter (PM_2.5) between the two cities; whereas, there were differences in the contents of cobalt (Co), nickel (Ni), copper (Cu), arsenic (As), and selenium (Se) in PM_2.5 between the two cities and the Ni content of PM_2.5 in Jinchang city was 82 times higher than that in Zhangye city. Totally 18 286 eligible records of hospitalized delivery were collected in Jinchang city and 15 518 records in Zhangye city during the period; the incidence rates of adverse pregnancy outcomes was 17.67 % in Jinchang city and 13.21 % in Zhangye city, with a significantly difference (χ² = 126.60, P < 0.01). The incidence rates of low birth weight, premature birth, birth defects in Jinchang city were significantly higher than those in Zhangye city.

  Conclusion   The risk of adverse pregnancy outcomes in Jinchang city was higher than that in Zhangye city and ambient air pollutants may be associated with the difference, especially for nickel content in PM_2.5.