How Rare Is Microsomia?

Hemifacial microsomia is the second most common facial birth defect behind cleft lip and palate, affecting one in every 3,500 to 4,000 births.

What causes microsomia?

What Causes Hemifacial Microsomia? The defect develops when the fetus is 4-weeks-old when it is thought that some kind of blood vessel problem results in a poor supply of blood to the face. No one knows what causes the condition; it can be caused by physical trauma but in most cases, it seems to occur by chance.

What is a microsomia mean?

Microsomia means abnormal smallness of body structures. Most people with craniofacial microsomia have differences in the size and shape of facial structures between the right and left sides of the face (facial asymmetry).