As state agencies struggle with major budget cuts, child advocates are alarmed about the future of hundreds of teens who “age out” of social services when they turn 18 and are let loose with little support to start perilous new lives.

“I worry it will be on the chopping block,” said Erik Pitchal, a Suffolk University Law professor and co-author of a June report on teens who outgrow the Department of Children and Families.

“I hope the commissioner will stand up to the governor and say, ‘You should not solve this fiscal emergency on the backs of the most vulnerable people in the population,’ ” he said. “They’ve had a rough go of it already.”

Some 800 teens a year turn 18 while in living in state care, including group and foster homes, and have no families. The study, underwritten by the Boston Foundation, found those youngsters are likelier to be depressed and hopeless, have trouble finding jobs, become pregnant or get someone pregnant, and run afoul of the law.