In most cases, an angry parent or caregiver shakes the baby to punish or quiet the child. Such shaking usually takes place when the infant is crying inconsolably and the frustrated caregiver loses control. Many times the caregiver did not intend to harm the baby. Still, it is a form of child abuse.
Injuries are most likely to happen when the baby is shaken and then the baby's head hits something. Even hitting a soft object, such as a mattress or pillow, may be enough to injure newborns and small infants. Children's brains are softer, their neck muscles and ligaments are weak, and their heads are large and heavy in proportion to their bodies. The result is a type of whiplash, similar to what occurs in some auto accidents.
Shaken baby syndrome does not result from gentle bouncing, playful swinging or tossing the child in the air, or jogging with the child. It also is very unlikely to occur from accidents such as falling off chairs or down stairs, or accidentally being dropped from a caregiver's arms. Short falls may cause other types of head injuries, although these are often minor.