畸形（体）;变形（体）the condition of being wrongly formed, or a part of something, such as part of the body, that is wrongly formed
Exposure to radiation can lead to malformation of the embryo. 接触射线会导致胎儿畸形。
She was born critically ill with a severe malformation of the heart. 她出生时心脏严重畸形，生命垂危。