The result showed chromosome abnormal is a basis reasons of Down syndrome, It has occasional and inducing factor such as years of morn, environment and so on have an important effect to it.

• 再次证明染色体畸变是唐氏征的根本原因，而导致染色体畸变的诱因有母亲的年龄，环境等因素，它具有偶发性。我们必须加强孕妇的环境保护，加强唐氏征的预防和筛查工作。