Abstract: ObjectiveTo explore the risk factors of isolated hypospadias and to provide evidence for decreasing the incidence of the disease.MethodsA hospital-based case-control study was conducted among 85 hypospadias patients and 85 non-hypospadias patients selected from Shengjing Affiliated Hospital of China Medical University from May 2010 to April 2011.The parents of the subjects were interviewed face-to-face with a questionnaire.Logistic regression model was used for univariate and multivariate analyses with SPSS17.0 software to estimate the odds ratios(OR)and 95 percent confidence interval(95% CI).ResultsThere were significant differences in the ratios of father with high school or higher education(23.5% vs 50.6%),the mother with high school or higher education(28.2% vs 47.1%),low birth weight(32.9% vs 5.9%),the mother with irregular menstruation before pregnancy(48.2% vs 15.3%),medication of the mother before pregnancy(32.9% vs 18.2%),intake of protein of the mother in early pregnancy,folic acid intake of the mother in early pregnancy(20.0% vs 36.5%),the mother with abnormal conditions during pregnancy(50.6% vs 25.9%),materal chemicals exposure before pregnancy and during early pregnancy(42.4% vs 16.5%),paternal occupational exposure to chemicals (68.2% vs 42.4%),and families engaged in agriculture and stockbreeding(49.4% vs 32.9%)between the case and control groups(P<0.05 for all).Multivariate analyses showed statistically significant associations of the 4 indexes with isolated hypospadias.Maternal exposure to chemicals during progestational time and first-trimester(OR=3.09,95% CI:1.41-7.629),abnormal conditions during pregnancy(OR=2.12,95% CI:1.18-4.14),father with high school or higher education education(OR=0.34,95% CI:0.17-0.72),and low birth weight(OR=5.28,95% CI:1.79-15.57)were the risk factors of isolated hypospadias.ConclusionMaternal exposure to chemicals in first-trimester,pregnancy with abnormal conditions,and low birth weight are the risk factors of isolated hypospadias.