[1] World Health Organization. Congenital anomalies. https://www.who.int/news-room/fact-sheets/detail/congenital-anomalies. [2020-09-01].https://www.who.int/news-room/fact-sheets/detail/congenital-anomalies
[2] World Health Organization. Congenital anomalies. https://www.who.int/health-topics/congenital-anomalies#tab=tab_1. [2020-09-01].https://www.who.int/health-topics/congenital-anomalies#tab=tab_1
[3] Ministry of Health of People’s Republic of China. Report on prevention and treatment of birth defects in China (2012). Beijing: Ministry of Health of People’s Republic of China, 2012. (In Chinese). 
[4] Christianson A, Howson CP, Modell B. March of dimes global report on birth defects. White Plains, New York: March of Dimes Foundation; 2006. https://www.marchofdimes.org/materials/global-report-on-birth-defects-the-hidden-toll-of--d2unzZI5_VWOaLZnw6iHcx7hbpMWtWzTuIOU3DabcVY.pdf. [2020-09-01].https://www.marchofdimes.org/materials/global-report-on-birth-defects-the-hidden-toll-of--d2unzZI5_VWOaLZnw6iHcx7hbpMWtWzTuIOU3DabcVY.pdf