The cost of treating babies born with neonatal abstinence syndrome (NAS), who experience withdrawal after being exposed to opioids during pregnancy, was $573 million in 2016, according to a new study in JAMA Pediatrics.

The rate of NAS increased from 1.5 per 1,000 U.S. hospital births in 2004 to 8 per 1,000 in 2014, then declined to 6.7 per 1,000 in 2016, CBS News reports.

Infants with NAS usually are born preterm or with low birth weight. They may need to be treated with morphine to wean them off opioids, according to Stephen Patrick, Director of Vanderbilt University’s Center for Child Health Policy, who co-wrote an editorial accompanying the study.

Getting pregnant women addicted to opioids into treatment can help their babies, Patrick said. “Medications for opioid use disorder like methadone and buprenorphine make it far less likely those babies will be born preterm, but they may still have withdrawal around the time of term,” he said.