MONDAY, Feb. 6 (HealthDay News) -- Close to 4,600 kids in the United States were hospitalized as a result of child abuse in one recent year, and 300 of them died, a new study shows.

Researchers from Yale University analyzed information from the 2006 Kids' Inpatient Database to determine the rate of hospitalizations due to serious physical abuse among children under the age of 18.

Infants aged 1 year or younger were at highest risk for child abuse-related hospitalization. The rate of hospitalization for 1-year-olds was about 58 per 100,000 children, a rate that is higher than that of sudden infant death syndrome (SIDS).

The hospitalization numbers are likely just "the tip of the iceberg," because many abused children don't end up in hospitals, said Karel Amaranth, executive director of the Butler Child Advocacy Center at The Children's Hospital at Montefiore in New York City.

Poverty appears to be another risk factor for child abuse. Children covered by Medicaid, the U.S. health program for low-income families, were about six times more likely to be victims of serious abuse as children who were not on Medicaid.

The new findings appear online and in the March issue of Pediatrics.

Things may have gotten even worse since 2006.

Research suggests that these rates may be even higher since the economy began to falter. One study found that the rate of abusive head trauma rose from about nine per 100,000 children to nearly 15 per 100,000 children from 2004 to 2009, which coincides with the onset of the recession and massive job losses. That study appeared in the October 2011 issue of Pediatrics.

Dr. Walter Lambert, an associate professor of pediatrics and medical director of University of Miami Child Protection Team, is not surprised by the findings.

"There is absolutely no doubt that since the economy started getting worse, the number of reports to child abuse hotlines has gone up and the severity injuries has increased as has the number of kids who end up in the hospital due to child abuse," Lambert said. Earlier identification of at-risk families may help stem some of the violence, he said.

The onus is on everyone in society to help buck this disturbing trend, Amaranth said. "Speak up in a very loud and clear voice because a lot of these children don't have the voice to speak for themselves," she said. "If you feel that a child is being harmed in some way, you have to call it in." Every state has a child abuse hotline.

More information

Visit Childhelp to learn how to protect children and prevent child abuse.