Small children who are shaken forcefully can develop bleeding around the brain (subdural hematomas) and bleeding on the back of the eye (retinal hemorrhages). Some lawyers have chosen to defend people accused of abusing children by saying that bleeding was caused by the pertussis component of the DTP vaccine. However, no evidence exists to support this contention. Neither pertussis nor the pertussis vaccine cause bleeding around the brain or on the back of the eye — only forceful shaking does this.