Abstract: Objective：To explore the environmental risk factors of different categories of congenital heart defects (CHD) and provide evidence for further risk factors and prevention research of CHD phenotypes. Methods: Data of Guangdong CHD Register Study from 2004 to 2012 were used. In the study, 3 038 CHD cases and 3 038 paired controls from 34 hospitals distributed in 17 cities were registered and related information were collected using uniform, and structured questionnaires. All the CHD phenotypes were coded according to the International Classification of Diseases 10^th Revision (ICD-10) and classified into 6 categories according to their pathological features. Univariate analyses were adopted to filter potential risk factors for each category of CHD. Then multivariate conditional Logistic regression was used to calculate the odds ratios of the risk factors for each category of CHD. Results: The risk factors for left-to-right shunt CHD included low (OR=2.63, 95%CI：2.04-3.39) or over birth weight (OR=2.21, 95%CI： 1.47-3.32), premature delivery (OR=1.95, 95%CI： 1.53-2.49), polyembryony (OR=1.99, 95%CI： 1.22-3.26), maternal low education, mother as factory worker (OR=1.62, 95%CI： 1.32-1.98), parity≥2 (OR=1.38, 95%CI： 1.13-1.69), maternal abnormal reproduction history (OR=2.29, 95%CI： 1.75-3.01), fever (OR=2.38, 95%CI： 1.26-4.48), virus infection (OR=1.80, 95%CI： 1.29-2.51), medicine usage (OR=1.73, 95%CI： 1.11-2.69), passive smoking (OR=1.69, 95%CI： 1.26-2.29), chemical agent contact (OR=8.71, 95%CI： 2.33-32.58), living in newly decorated houses (OR=2.56, 95%CI： 1.60-4.09) or room close to the main road (OR=1.40, 95%CI： 1.14-1.72) in the first 3 months of pregnancy and father as factory worker (OR=1.46, 95%CI： 1.23-1.73). The risk factors for pulmonary outflow tract obstruction CHD included low (OR=5.98, 95%CI： 2.88-12.44) or over birth weight (OR=6.56, 95%CI：1.19-36.26), maternal low education, parity≥2 (OR=2.08, 95%CI： 1.03-4.22), virus infection in the first 3 months of pregnancy (OR=4.30, 95%CI： 1.27-13.45). The risk factors for left ventricular outflow tract obstruction CHD included father as factory worker (OR=6.01, 95%CI：1.05-34.59). The risk factors for transposition of the great arteries included low birth weight (OR=12.93, 95%CI:1.14-146.26), maternal low education, mother as factory worker (OR=3.69, 95%CI:1.53-8.91). The risk factors for conditions with intra cardiac mixing of oxygenated and deoxygenated blood included parity=2 (OR=3.45, 95%CI： 1.42-8.38). The risk factors for other CHD included over birth weight (OR=4.87, 95%CI： 1.19-19.94), maternal abnormal reproduction history (OR=2.96, 95%CI： 1.14-7.68), virus infection (OR=4.92, 95%CI： 1.56-15.47), medicine usage (OR=4.90, 95%CI： 1.22-19.77) or passive smoking (OR=10.31, 95%CI： 1.25-85.05) in the first 3 months of pregnancy. Conclusion：The environmental risk factors were discrepant among different categories of CHD. Further risk factors study of CHD phenotypes should be performed specially. To prevent CHD, attention should be paid to the risk factors which are related to multi or complex categories of CHD.

Key words: Heart defects, congenital, Pathology, Risk factors