At least 89 children have died in the past 13 months while acting on behalf of the Islamic State, according to a new study suggesting the group has more child soldiers than previously thought.

The study, published Thursday by the Combating Terrorism Center at West Point, says that the Islamic State “is mobilizing children and youth at an increasing and unprecedented rate.”

It focuses on the 89 children and teenagers who the Islamic State has publicly eulogized as martyrs since January 1, 2015, shining a light on how the group uses children in its operations.

The study found children are largely being given the same roles as their adult counterparts and “are fighting alongside, rather than in lieu of” men. The findings suggest the Islamic State’s “systematic use of children is more widespread than previously imagined,” the report states.

The Islamic State does not publicize the ages of the deceased children, so the researchers had to rely on photographs to determine their approximate ages. They found 60 percent of the child soldiers were believed to be adolescents (ages 12 to 16), 6 percent appeared to be pre-adolescent (ages 8 to 12) and the remaining 34 percent seemed to be older adolescents (ages 16 to 21).

Many of the children died setting off vehicle bombs (39 percent) or as soldiers on the battlefield (33 percent). Another 18 percent died in “inghimasi” attacks, where a mix of adult and child soldiers shoot their way into enemy territory before blowing themselves up. The others were killed while working as propagandists among Islamic State units or in attacks against civilians.

The study found that 87 percent of the children were purportedly killed in Iraq or Syria, where the group controls large portions of land, while the others died in Libya, Nigeria and Yemen.

Researchers acknowledge the data isn’t all-encompassing — they noted the Islamic State did not publicly release photographic propaganda about every one of its suicide attacks last month, for example — but they maintain the report is the most comprehensive analysis of its kind to date.

They also warned that the Islamic State utilization of child soldiers appears to be on the rise, saying 11 were killed in suicide missions last month compared to just six during January 2015.

A spokesman for the United States-led coalition against the Islamic State has said Iraqi forces have regained significant amounts of territory the insurgency once held in Iraq and Syria, and airstrikes recently destroyed “significant amounts” of cash the group used to fund its operations.

The report suggests a potential link between recent military pressure and the uptick in deaths.

“It seems plausible that, as military pressure against the Islamic State has increased in recent months, such operations — especially those of the inghimasi variety — are becoming more tactically attractive,” it states. “They represent an effective form of psychological warfare. … We can expect that as their implementation increases, so too will the reported rate of child and youth deaths.”