In most cases of scoliosis the cause is unknown; the vertebrae and spinal structures-discs, ligaments, tendons and muscles-all appear normal. In the rest of the cases the scoliosis is caused by conditions such as a tumor, infection, cerebral palsy, muscular dystrophy, a birth deformity or disc problems. Further deepening the mystery of scoliosis is the fact that no one knows why some minor curves get worse whereas about 90% do not. However, it is not true, as commonly thought, that poor posture is a cause of scoliosis or that women with scoliosis have more problems carrying babies to term. In fact, most people with scoliosis can lead normal lives, never even knowing that they have the condition. No one dies from scoliosis, but in severe cases scoliosis sufferers can have breathing or heart problems if the curve is very severe.