A baby is born every hour in the United States with signs of opiate drug withdrawal, and the number of newborns in withdrawal has tripled over the past decade, according to a US study.     

Researchers of the study, which was published in the Journal of the American Medical Association, also found that the number of new mothers who tested positive for use of opiates, which include powerful painkillers such as oxycontin, increased five-fold between 2000 and 2009.

In the most recent study year, between five and six out of every 1,000 women had the drugs in their system.

“This study is part of a bigger call to the fact that opiates are becoming a big problem in this country,” said Stephen Patrick of the University of Michigan in Ann Arbor, who worked on the study.

Recent research has shown the number of people who both abuse opiates and who overdose has been increasing in the United States. According to the Centers for Disease Control and Prevention, 14,800 people died of a prescription drug overdose in 2008, triple the estimate from 20 years earlier.

Data from discharge records for children treated at more than 4,000 hospitals nationwide and statistically adjusted to represent the entire US population showed that the number of infants born with signs of opiate withdrawal increased from one in 1,000 in the year 2000, to more than 3 in 1,000 by 2009.

That works out to about 13,500 newborns born in withdrawal across the United States in 2009.

It's unclear if there are long-term health impacts for children born to opiate-addicted mothers who get through their first weeks of life okay. Some but not all studies on the question have found those kids grow up with a higher risk of developmental problems, according to Patrick.

What is clear is that babies born in opiate withdrawal significantly drive up health care costs.

According to the study, the average hospital stay for a newborn in withdrawal averages 16 days, compared to just three days for other newborns. Care costs were more than five times higher.

It's usually not difficult to spot a baby in opiate withdrawal, Patrick said.

“(They) are far more inconsolable than other babies. They appear uncomfortable, sometimes they breathe a little faster ... they're scratching their faces,” he said.

At this time, the increasing abuse of prescription opiate medications - and babies being born in withdrawal - is mainly centered in a few places of the United States, including in rural Kentucky, Tennessee and Maine. Parts of Florida are also becoming known as hubs of opiate abuse, said Marie Hayes, from the University of Maine in Orono.

“The concern is that it will be more widespread,” said Hayes, who wrote a commentary published with the new study.

In a few cases, babies born in withdrawal have mothers that needed to be on strong painkillers after they were in a car accident, for example. A very small number had mothers who were addicted to heroin.

But about 85 per cent of the cases Hayes sees are the result of women who abuse prescription drugs.

Researchers agreed that there's a need for more research on how best to care for drug-addicted women and babies who are born in withdrawal, as well as an urgency to spread the message about the dangers of opiate use in pregnancy.

“We need to put the light on this problem, and get it out there as a public health crisis,” Hayes said.