The cry of a baby withdrawing from prescription opiates is shrill, as if the child is in terrible pain.

"It's a very high-pitched, uncomfortable cry," said Dr. Aimee Bohn, a pediatrician with Mountain Comprehensive Health Corporation in Whitesburg, Kentucky. "It's like the kid has been pinched."

That characteristic cry is increasingly ringing through the hallways of hospitals nationwide, according to new research.

By 2009 there were more than 13,000 babies born with neonatal abstinence syndrome, a withdrawal syndrome that occurs in some babies after being exposed to a class of painkillers, called opiates, while in utero, according to the study published Monday.

"That's about one baby per hour," said Dr. Stephen Patrick, lead author of the study, which was published online in the Journal of American Medical Association. "We were surprised by it. That's a startling increase."

Perhaps more startling - that one baby per hour figure marks about a three-fold increase in the number of babies born with NAS since 2000; and during the same time period, opiate use among expectant mothers was also jumping, increasing nearly five-fold.

"There has been an incredible increase in the number of opiate pain relievers prescribed in the U.S.," said Patrick, a fellow in the University of Michigan's Division of Neonatal-Perinatal Medicine. "We think that might be part of the increase we are seeing."

Patrick says he undertook the study after he and colleagues from other hospitals began noticing more and more babies in their neonatal intensive care units with hallmarks of NAS, which includes increased irritability, respiratory and feeding problems, low birth weight and, rarely, seizures.

Using hospital billing data from the Kids' Inpatient Database, they identified which newborns were discharged with an NAS diagnosis to arrive at a national estimate.

Bohn says that a couple of years ago, one baby per hour born withdrawing from opiates would have surprised her. Today, she says, it is not surprising based on what she is seeing in eastern Kentucky, part of an area known as "ground zero" of prescription drug abuse.

"Women you would never guess have a problem because they are functioning in society come in addicted," said Bohn.

Those mothers, said Bohn, are having babies with NAS at a rate of 1-2 cases per week, on a busy month, at her hospital. And that does not include babies who are exposed to prescription painkillers in utero, but somehow escape the overt symptoms at birth.

"A lot of times, the babies are a little jittery, they shake when they first come out," said Bohn. "They become cranky, they don't sleep and they develop terrible diaper rashes."

The average hospital stay for a baby born withdrawing from painkillers is 16 days, according to the JAMA study, and 77% of the time, babies with NAS were charged under state Medicaid programs.

"What we found is that the total U.S. hospital bill quadrupled over the time frame [2000-2009] nearing 720 million dollars," said Patrick. "That is extra incentive for state governments to engage in developing solutions to prevent this."