Our center has constructed multi-center collaborative network in 2013, so far which contains more than 170 maternal and child health care hospitals throughout the whole of China. This is a multi-center-based study to improve the integral diagnostic level of fetal congenital heart diseases by fetal echocardiography. Sixty pregnant cases (18-45 years) whose fetuses with heart abnormalities will be recruited in a successive manner from every center every year. Cases are gravidas with fetal congenital heart disease diagnosed by echocardiography in 16th-24th of gestational weeks. Every center will upload the echocardiography materials and the diagnostic reports so that another two experienced echocardiography physicians confirm the diagnosis based on these materials in a double-blinded method. In addition, the golden standard of congenital heart disease depends on the autopsy, heart and vascular casting after abortion and operation after birth. The investigators will provide the report about the rate of missed diagnosis and misdiagnosis and the periodical training on fetal echocardiography for every center every half an year. Only gravidas who are willing to have complete pregnancy checks and finally delivery or abortion in the hospital are interviewed are eligible for the study. Study participants will be asked for their informed consent.