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

它可生前通过绒毛-绒毛取样穿刺术完成。

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

可产前通过检测胎儿DNA完成，如绒毛绒毛取样穿刺术。

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

核型分析生前就可用穿刺术取样生后采血取样。

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，需行穿刺术，即直接从胎儿周围的囊穿刺取样检查。