What causes birth defects?
Genetics In ancient times, abnormalities were seen as warnings or punishments from the gods. Even quite recently, it was believed that specific events during the pregnancy – such as being frightened by a mouse – would lead to specific defects in the baby, eg a mouse shaped birth mark. Such folk beliefs still persist in places. However, most defects that can be traced to a single cause have a genetic origin. This does not necessarily mean that the parents suffer from the same defect. It may be that they are carriers of the condition, or that the genetic problem occurred for the first time in the cells that gave rise to the baby. Known genetic causes account for about 25 per cent of all abnormalities. Environment Environmental causes (including exposure to drugs, radiation and illnesses) can be identified in about 10 per cent of birth defects. The risk of exposure to such environmental factors often causes great concern, although genetic causes are more common. Other factors The exact ca