In 2000, approximately 4,300 babies were born with neonatal abstinence syndrome, a condition that occurs in some babies that were exposed to opiates such as heroin, Vicodin and oxycodone in the womb, according to the study. In 2009, the number jumped 300 percent to 13,000.
"That's about one baby per hour," Dr. Stephen Patrick, lead author of the study and postdoctoral researcher at the University of Michigan, told CNN. "We were surprised by it. That's a startling increase."
Opiates used by an expectant mother during pregnancy pass through the placenta and into the baby. The babies' bodies become dependent on the drugs but no longer have access to them once they are born, triggering withdrawal. Between 55 percent and 94 percent of babies exposed to the drugs before birth show signs of withdrawal once they are born, according to the American Academy of Pediatrics.
Signs of withdrawal unique to infants include a distinct, high-pitched cry and an aversion to light and sound. They may also show symptoms similar to adult withdrawal patients, such as insomnia, diarrhea and vomiting.
Doctors use methadone, a drug used by addicts looking to kick the habit, to wean the babies off of the drugs slowly. Making them go cold-turkey could lead to seizures and possibly death, according to the study.
Getting the babies over their addiction could take weeks or even months and often requires long-term hospitalization. The cost of treating drug-addicted babies increased from $190 million in 2000 to $720 million in 2009, according to the study, published in the Journal of the American Medical Association on Monday.
The increase in opiate-addicted babies is a product of growing numbers of adults who abuse painkillers.. More than two-thirds of patients prescribed painkillers abuse them by taking them too often or by taking them in conjunction with other painkillers not prescribed to them, according to research published by Quest Diagnostics.
In addition, two million people in 2010 admitted to abusing prescription painkillers for the first time -- almost 5,500 per day, according to the Centers for Disease Control and Prevention.
Tennessee had the highest rate of painkiller abuse between 2007 and 2008, according to the National Survey on Drug Use and Health. It also has one of the highest rates of opiate-addicted newborns. At East Tennessee Children's Hospital, almost 50 percent of the babies in the neonatal intensive care unit are experiencing withdrawals.
"In Knox County, we're drowning," Susan Kovac, attorney for the Department of Children's Services in Tennessee, told CNN. "We've seen the number of children in foster care increase by almost 50 percent over the last few years, and that's just the tip of the iceberg because we're trying to keep the children out of foster care. We've got lots and lots of relatives who are raising drug-exposed infants."
Florida also experienced a surge in the number of addicted babies, which increased from 354 in 2006 to 1,374 in 2010, according to the study.
The researchers call for individual states and the Federal government to take action to reduce the amount of painkillers prescribed and say educating the public about the dangers of using the drugs while pregnant may also help. Cutting the number of prescriptions of opiates could drastically reduce the number of babies born with NAS, according to the study.
"Newborns with NAS experience longer, often medically complex and costly initial hospitalizations," the researchers wrote in the study. "The increasing incidence of NAS and its related health care expenditures call for increased public health measures to reduce [in utero] exposure to opiates across the United States."