Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. "Congenital" means "present at birth."
Birth defects of the face and skull (called craniofacial anomalies) are fairly common. They may involve only a specific body part, such as the mouth (cleft lip or cleft palate), or they may be part of a genetic syndrome with many abnormalities, such as Treacher Collins syndrome, in which birth defects affect not only the face but also multiple other body parts.
Craniofacial anomalies are caused by the abnormal growth or development of the head and/or facial bones while the baby is growing inside the mother. The most common defects of the face are cleft lip and cleft palate. Other defects may involve the ears, eyes, and jaw. Some craniofacial anomalies that affect the skull include macrocephaly (the skull is too large), microcephaly (the skull is too small), and craniosynostosis (the junctions between the bones of the skull close too early).
Birth defects may be classified as
Deformities
Malformations
A deformity is a change in the shape of a body part. A deformity is caused by unusual pressure on the baby in the womb (for example, the outer shell of an ear is folded) or after the baby is born (for example, some deformities of the skull). Deformities are present in about 2% of births. Some deformities improve without treatment within a few days, but others need to be treated.
A malformation is an error in the baby's development that occurs in the womb. Causes of malformations include chromosome abnormalities, single-gene defects, and environmental factors (such as teratogens, which are substances known to cause birth defects). A malformation can also be caused by a combination of genetic and environmental factors. In some cases, the cause is unknown. About 3 to 5% of babies are born with a malformation.
