Congenital heart defect cases was 1.05 (95%CI:1.01to1.10).For continuous exposure to PM2.5 (5 μg/m3 increase), the adjusted OR for patent ductus arteriosus cases was 0.78 (95%CI:0.68to0.91). For the gaseous pollutants, CO , O3 , NO2 and SO2, there was no association between maternal exposure during pregnancy and risks of isolated patent ductus arteriosus, ventricular septal defect and atrial and atrial septal defects or multiple congenital heart defect cases.