The number of babies being born in the United States addicted to opioids has tripled in a 15-year stretch, according to a government report published Thursday.

The Centers for Disease Control and Prevention said in its most recent Morbidity and Mortality Weekly Report that the findings, based on hospital data, are likely underestimates of the true problem and point to an urgent need for public health efforts to help pregnant women deal with addiction.

The CDC found that the incidence of neonatal abstinence syndrome jumped to 6 per 1,000 hospital births in 2013, up from 1.5 per 1,000 in 1999. The data came from 28 states with publicly available data on opioid addiction.

While the report showed huge jumps in nearly every state, the hardest hit were Maine, Vermont, and West Virginia. In West Virginia, 33.4 of every 1,000 babies born went through withdrawal symptoms in 2013.

Babies going through NAS suffer from gastrointestinal dysfunction, temperature instability, and central nervous system problems, such as tremors, high-pitched crying, and seizures.

The most common cause of NAS is opioid exposure in the womb, although it is sometimes caused by other substances. It can result from prescription opioid use, non-medical opioid use, or the use of drugs like methadone, intended to wean people off opioid dependency.

The CDC’s report is among the most comprehensive to date looking at the rise of opioid dependency in babies amid the nation’s spiraling abuse crisis. Its findings were consistent with smaller studies that have raised concern about dramatic increases in babies born with NAS. It noted that state governments play an especially important role in addressing the problem, as their use of funds passed down from the federal government pay the bulk of treatment costs. Medicaid programs administered by states were responsible for covering 80 percent of the $1.5 billion charges for treatment of neonatal opioid withdrawal at US hospitals in 2012.

Earlier this year, the CDC released the Guideline for Prescribing Opioids for Chronic Pain, which recommended that clinicians take the following steps: consider prescribing non-opioid pain management, talk about how opioid use might affect pregnancy, and when prescribing, start with the lowest effective dose possible.