Birth defects, also sometimes called "congenital abnormalities" by physicians, are abnormalities in either a baby's physical appearance, or in the way that their body functions. Some birth defects may be apparent when attending a prenatal check-up, either showing up in a mother's blood work or on the scan of the baby. Other birth defects may only become apparent when the baby is born, or while they are young children. Birth defects may arise from a number of causes, for example they may be genetic or they may arise as a result of environmental factors, such as exposure to certain drugs during pregnancy. There are lots of different types of children birth defects which are currently known, and these vary greatly in severity. Some appearance defects may become easier to live with as the child grows older, but some functional defects may lead to lifetime disability or even death.