SOURCES: Stephen Patrick, M.D., M.P.H., M.S., assistant professor, pediatrics and health policy, division of neonatology, Vanderbilt University, Nashville, Tenn.; Jennifer Wu, M.D., obsetrician-gynecologist, Lenox Hill Hospital, New York City; April 13, 2015, Pediatrics, online; April 26, 2015, New England Journal of Medicine; April 26, 2015, presentation, Pediatric Academic Societies annual meeting, San Diego
SUNDAY, April 26, 2015 (HealthDay News) -- The number of U.S. infants admitted to neonatal intensive care units to treat symptoms of drug withdrawal has nearly quadrupled since 2004, researchers report.
Neonatal abstinence syndrome -- a drug-withdrawal syndrome that often occurs after exposure to prescription narcotic painkillers during pregnancy -- affected only seven babies for every 1,000 admitted to a neonatal intensive care unit (NICU) in 2004. By 2013, that number had jumped to 27 infants for every 1,000 babies in the NICU, the study revealed.
The Baylor University Medical Center researchers also found that the percentage of days spent in a NICU attributed to drug withdrawal went from 0.6 percent to 4 percent over that decade. And eight neonatal centers reported that more than 20 percent of NICU days were spent caring for these infants in 2013.
The findings were published online April 26 in the New England Journal of Medicine, to coincide with a presentation at the Pediatric Academic Societies annual meeting in San Diego.
Another recent study -- published April 13 in the journal Pediatrics -- found that the use of prescription narcotic painkillers can be startlingly common in pregnancy. The prescription painkillers, also called opioids, include drugs such as hydrocodone (Vicodin), oxycodone (Oxycontin), codeine and morphine.
Nearly 30 percent of the Tennessee mothers-to-be in the Pediatrics study used at least one of these drugs while pregnant, and the associated risks went up if they also smoked or took antidepressants.
"I was surprised by the number of women prescribed opioid pain relievers in pregnancy," said lead author Dr. Stephen Patrick, a neonatologist and assistant professor of pediatrics at Vanderbilt University in Nashville. "I was also surprised by how commonly women smoked in pregnancy, and how much that increased the risk of neonatal abstinence syndrome among those who also used opioid pain relievers in pregnancy."
The Tennessee study reviewed medical records of more than 112,000 women in the Tennessee Medicaid program between 2009 and 2011. Of these women, about 28 percent had filled a prescription for at least one narcotic painkiller.
The vast majority took short-acting medications, such as hydrocodone or oxycodone. Only 3 percent were on maintenance therapy for addiction to illegal narcotics, such as heroin.
"Some women need to take opioids in pregnancy to improve their infant's outcome," Patrick explained. "For women with opioid dependency, we know that use of maintenance opioids like methadone decrease rates of preterm birth compared to heroin. For these women, neonatal abstinence syndrome may occur in their infants, but it is much better than the alternative, which is preterm birth."
The women prescribed painkillers were more likely to be white. They were more apt to report headaches or migraines and muscular or skeletal health problems. They were also more likely to have depression, to have an anxiety disorder and to smoke tobacco.
Forty-two percent of the women prescribed narcotics smoked during pregnancy. The more cigarettes a woman smoked daily, the more likely she was to give birth to a baby with withdrawal.
"That's a modifiable behavior," Patrick said. "For women who are in maintenance treatment, dose didn't change the risk of neonatal abstinence syndrome, but smoking mattered a lot. So you can modify your infant's risk of drug withdrawal if you decrease the amount you smoke."
Taking selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant, with prescription narcotics also doubled the risk of newborn withdrawal, the study found.
The Tennessee researchers found that infants with neonatal abstinence syndrome were twice as likely as other newborns to be born at a low birth weight. They were also far more likely to have respiratory conditions, feeding difficulties and seizures.
Dr. Jennifer Wu, an obstetrician-gynecologist at Lenox Hill Hospital in New York City, said that "with this increase in prescription painkiller use, we're seeing an effect in our newborn population. If you think about how vulnerable our newborns are, this is really frightening."
Learn more about drugs in pregnancy from the U.S. Centers for Disease Control and Prevention.