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

它可以在出生绒毛膜-绒毛取样或羊膜完成。

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

可以在产检测胎儿DNA完成，如绒毛膜绒毛取样或羊膜。

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

核型分析在出生就可以用羊膜取样或在出生后采血取样。

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

在严重的情况下，需行羊膜，即直接从胎儿周围的羊膜囊取样检查。