Nearly 4,600 U.S. children were hospitalized with broken bones, traumatic brain injury and other serious damage caused by physical abuse in 2006, according to a new report. Babies younger than one were the most common victims, with 58 cases per 100,000 infants. That makes serious abuse a bigger threat to infant safety than SIDS, or sudden infant death syndrome, researchers say in the report. There is a national campaign to prevent SIDS," said Dr. John Leventhal of Yale University, who led the new study. "We need a national campaign related to child abuse where every parent is reminded that kids can get injured." Based on data from the 2006 Kids' Inpatient Database, the last such numbers available, Leventhal's team found that six out of every 100,000 children under 18 were hospitalized with injuries ranging from burns to wounds to brain injuries and bone fractures. The children spent an average of one week in the hospital; 300 of them died. The rate of abuse was highest among children under one, particularly if they were covered by Medicaid, the government's health insurance for the poor. One out of every 752 of those infants landed in the hospital due to maltreatment. "Medicaid is just a marker of poverty, and poverty leads to stress," said Leventhal, who is the medical director of the Yale-New Haven Children's Hospital Child Abuse Program.