U.S. Health and Human Services Secretary Sylvia Burwell says the department is taking a more proactive approach to enforcing a federal law that requires states to report and protect drug-dependent babies.

Speaking at a congressional committee hearing Tuesday, Burwell said, “Specific actions are being taken where we have found there is wrongdoing.” She did not provide details of the plan, Reuters reports.

The House Education and the Workforce Committee launched an inquiry into the federal government’s enforcement of a law designed to protect drug-dependent newborns. The inquiry is in response to a Reuters investigation that found 110 cases of babies and toddlers whose mothers used opioids during pregnancy, and later died preventable deaths.

In each case, the babies recovered enough to be discharged from the hospital, but were sent home to families not equipped to care for them.

Burwell said the Reuters investigation triggered a review of several states. South Carolina is being placed on a “performance improvement plan,” she told the committee.

The number of babies treated for the drug-withdrawal syndrome known as neonatal abstinence syndrome (NAS) has almost quadrupled in the last decade, according to a study published last year.

Babies born with NAS undergo withdrawal from the addictive drugs their mothers took during pregnancy, such as oxycodone, morphine or hydrocodone. NAS affected seven babies for every 1,000 admitted to a neonatal intensive care unit in 2004. That number jumped to 27 infants per 1,000 by 2013.

Reuters found that no more than nine states comply with a 2003 law that calls on hospitals to alert social workers whenever a baby is born dependent on drugs.