Results: The maternal exposed factors such as abortion, long time and low dose radiation, passive smoking, drinking, MSG ( monosodium glutamate), contraceptive tablet, anti-infection drug were considered to be related to a higher incidence of DS. 结果母亲自然流产史、长期接触电脑等辐射、长期被动吸烟、饮酒、使用多量味精、孕前服用避孕药及抗感染药是DS发生的危险因素。