Between 2009 and 2012, the number of babies born with NAS almost doubled, from 3.4 births per 1,000 to 5.8 births per 1,000.
Neonatal abstinence syndrome (NAS) can occur among infants born to mothers who have used illicit drugs or prescription opioids during pregnancy, such as heroin, codeine and oxycodone.
When a woman uses such drugs during pregnancy, the baby is also exposed to them as they pass through the placenta. Because the baby is no longer exposed to the drugs after birth, they may experience withdrawal symptoms, including diarrhea, excessive or high-pitched crying, fever, vomiting and irritability.
In recent years, there has been a dramatic increase in the prescription of opioid painkillers. A 2014 report from the Centers for Disease Control and Prevention (CDC) found that in 2012 alone, around 259 million prescriptions for painkillers were written - the equivalent to one bottle for every adult in the US.
One baby born with NAS every 25 minutes
For their study, lead author Dr. Stephen Patrick and colleagues from Vanderbilt University Medical Center in Nashville, TN, set out to see how the rise in the use of prescription opioids has impacted the number of babies in the US born with NAS.
In order to gather information on incidence of NAS in the US, the team analyzed 2009-12 data from two national databases - the Kids' Inpatient Database and the Nationwide Inpatient Sample.
The researchers found that during the 4-year period, the number of babies born with NAS almost doubled, from 3.4 births per 1,000 in 2009 to 5.8 births per 1,000 in 2012 - the equivalent to one baby born with NAS every 25 minutes.
On assessing the incidence of NAS since 2000, the team found it has increased by almost fivefold.
Commenting on these results, senior author Dr. William Cooper says:
"The findings of this study demonstrate that neonatal abstinence syndrome is a growing public health problem in the United States and places a tremendous burden on babies, their families, and the communities in which they live."
Rise is NAS 'mirrors rise in opioid use'
When the team analyzed the data by geographical location, they found that the east-south central division of the US - including Tennessee, Kentucky, Mississippi and Alabama - had the highest incidence of NAS, with 16.2 babies born with the condition in every 1,000.
According to the CDC, these areas also have the highest rates of painkiller prescriptions per person.
New England had the next highest NAS incidence, at 13.7 births per 1,000, while the west-south central division had the lowest rates, at 2.6 births per 1,000.
"The rise in neonatal abstinence syndrome mirrors the rise we have seen in opioid pain reliever use across the nation," says Dr. Patrick. "Our study finds that communities hardest hit by opioid use and their complications, like overdose death, have the highest rates of the NAS."
What is more, the team identified a significant increase in national health care expenditures for NAS between 2009 and 2012, rising from $731 million to $1.5 billion.
The team believes their findings emphasize the importance of interventions to prevent opioid misuse among pregnant women.
"Too often in our health system we react to problems instead of forging public health solutions," says Dr. Patrick. "Imagine if we were able to use the dollars spent to treat NAS on improving public health systems aimed at preventing opioid misuse and improving access to drug treatment for mothers."
Medical News Today recently reported on another study by Dr. Patrick and colleagues at Vanderbilt, which was published in the journal Pediatrics.
In that study, the team found that opioid painkillers are commonly being prescribed for pregnant women, increasing the risk of their babies being born with NAS. Of the babies in their study who were born with the condition, 65% had mothers who had been prescribed opioid painkillers.