(CNN) -- The cost of treatment for infants in US hospitals who had been exposed to opioids rose by more than $250 million over four years, according to a study published Monday.
In 2012, total hospital costs to treat neonatal abstinence syndrome were $316 million. By 2016, according to the study published in the Journal of the America Medical Association Pediatrics, that number was up to $572.7 million.
Neonatal abstinence syndrome, known as NAS, occurs primarily in infants who were exposed to opioids while in utero. Newborns with NAS were hospitalized an average of 15.9 days, costing an average $22,550 per infant in 2016, the study said.
"In 2016, Medicaid was responsible for 83% of charges for in-hospital births with an NAS diagnosis, indicating that state and federal budgets may continue to bear disproportionate costs as the opioid crisis evolves," according to the study.
The rate of NAS births has risen significantly.
The rate of NAS soared from 1.5 in every 1,000 hospital births in 2004 to 8 in every 1,000 in 2014. In 2016, there were 6.7 cases of NAS for every 1,000 hospital births, the study said.
Opioid use during pregnancy has been linked to maternal mortality and risk of overdose for the mother, according to the CDC, while infants risk preterm birth, low birthweight, breathing problems and feeding problems.
An estimated 10.3 million Americans aged 12 and older misused opioids in 2018, including 9.9 million prescription pain reliever abusers and 808,000 heroin users. More than 130 people died every day from opioid-related drug overdoses in 2016 and 2017, according to the US Department of Health & Human Services.
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