Cause
The condition develops during the fetal stage of pregnancy at approximately 4 weeks of gestation, when some form of vascular problem leads to clotting and a poor supply of blood to the face. This can be caused by a physical trauma, though there is some evidence of it being hereditary . This restricts the developmental ability of that area of the face. Currently there are no definitive reasons for the development of the condition.
Read more about this topic: Hemifacial Microsomia