The U.S. economic slump has been accompanied by a sharp rise in child abuse, a recent study reveals.

A new study shows that from 2004 to 2009, a total of 422 children under the age of five were admitted to Kentucky, Ohio, Pennsylvania and Washington hospitals with abusive head injuries. Most of them had to be admitted to the intensive care unit and 16 percent died of the injuries.

The study deals with the shocking data which revealed that before recession, the rate of abusive head trauma in three distinct areas of the country was 8.9 per 100,000, but once the recession struck in 2007, the number increased to 14.7 per 100,000.

According to Dr. Rachel Berger of Children's Hospital of Pittsburgh and colleagues, from a clinical perspective, this association might warrant changes in the threshold for physicians to evaluate for [acute head trauma] during times of economic stress in the same way that physicians change the threshold to test for and treat pertussis during a pertussis outbreak.

Berger is the lead author of the study.

The average age of the victims was nine months, and 75 percent of them were not yet one year old. Almost 60 percent of the victims were boys and 67 percent of them were white.

Earlier, many studies identified the relationship between unemployment and economic stress with health problems in adults, and some studies linked financial hardship and child abuse.

In an interview with Reuters Health, Elizabeth Gershoff, a psychologist at the University Texas at Austin who studies parenting but is not involved in the study said, Living in poverty for parents can be very stressful and that in turn leads to harsher punishment. The increasing number of child abuse is definitely disturbing, she added.

Federal data showed a decline in the rate of child abuse since 2008, but the discrepancy in the number of cases is a result of very restrictive definition of abuse, Berger said.

Although it is not possible to prove a causal relationship between the [abusive head trauma] rate and the economy with our analysis, we believe the data are compelling enough to influence policy and clinical decisions, Berger and colleagues stated.

Limitations of the study included the possibility of bias among five studied hospitals and differences in classification of abusive head trauma, said Berger and colleagues.

The new findings were published Monday in the journal Pediatrics.

Pennsylvania Pennsylvania Medicine U.S.