It can be done before birth via chorionic-villus sampling or amniocentesis.

它出生前通过绒毛膜-绒毛取样或羊膜穿刺术完。

This can also be done prenatally by testing fetal DNA obtained through either chorionic villus sampling or amniocentesis.

产前通过检测胎儿DNA完，如绒毛膜绒毛取样或羊膜穿刺术。

A karyotype can be done before birth with an amniocentesis or at any time after birth with the blood test.

核型分析出生前就用羊膜穿刺术取样或出生后采血取样。

In more serious cases, amniocentesis, where a sample is taken directly from the amniotic sac surrounding the fetus, can be performed.

严重的情况下，需行羊膜穿刺术，即直接从胎儿周围的羊膜囊穿刺取样检查。