Dozens of pre-kindergartners were suspended last school year in Maryland, with the most suspensions in Baltimore, highlighting a little-known practice that some education experts say is too extreme for toddlers who are just being introduced to educational settings.

The number of out-of-school suspensions in Baltimore for children ages 3 and 4 nearly doubled since the previous year to 33, according to data provided by the city school system.

Some other area districts reported just a handful of pre-K suspensions in the last school year, while Anne Arundel County reported 19 and Howard County officials said they have never suspended a child that young.

The practice comes to light as the city school system is revising its suspension policy to require schools to eliminate automatic suspensions for certain violations and first requiring other interventions, such as parent conferences.

The pre-K suspensions also underscore a broader debate about zero-tolerance policies, sparked by young children being suspended for actions such as making gun hand gestures and chewing a breakfast pastry in the shape of a gun. Such policies are aimed at making schools safe, but some say they have been taken too far.

David Beard, education policy director at Advocates for Children and Youth, said any school system should be hard-pressed to find a reason to suspend 3- or 4-year-olds, because they are too young to understand such a consequence.

"Anything before third grade, really, a suspension makes no sense," Beard said. "Just in terms of their brain development … they don't know the difference from a vacation. It's really concerning for these really young kids, because that's a really critical time when they're supposed to be learning their letters and their numbers."

Across Maryland, 91 pre-K students were suspended or expelled in the 2011-2012 school year, the most recent year with statewide data available. That compares to 75 in 2009 and 105 in 2010.

Most of the students were suspended for physical attacks on teachers or students, though a handful were suspended for offenses such as sexual activity, possession of a firearm or other guns, inciting a public disturbance, and vandalism.

The data also show that pre-kindergartners were suspended for insubordination and disrespect, classroom disruption and refusing to obey school policies.

Bill Reinhard, a spokesman for the Maryland State Department of Education, said the state is concerned about suspensions at all grade levels and "believes that too many students are suspended out of school for nonviolent activity, and that too many suspended students do not receive the educational services to which they are entitled under the law."

The state school board is overhauling its discipline regulations to require districts to eliminate "zero-tolerance" policies and greatly reduce the number of suspensions for nonviolent offenses such as insubordination.

Beard noted that the proposed state regulations, which he supports, may not have an impact on pre-K students because the policies target older students who are out of school for long periods of time.

He hopes the state's discipline reforms will evolve to differentiate among grade levels because data show that children's chances of suspension rise when they become full-time students.

He pointed to state data showing a suspensions jump between pre-K and kindergarten. In the 2011-2012 school year, 673 kindergartners were suspended in Maryland — a number that has risen each year since 2008.

"The multiplier there is huge," Beard said. "I don't know what happens to these kids, whether or not they go to summer camp with the devil or something. But it seems it's our patience with them that changes."

Walter S. Gilliam, director of the Edward Zigler Center in Child Development and Social Policy at the Yale School of Medicine, said it would be in the state's best interest to investigate how it can reduce the number of students who are pushed out of school before they've started full time.

Maryland school districts have funneled millions of dollars into pre-K programs — Baltimore City's costs about $29 million per year — and there are continual efforts to expand them.

"We invest in preschool programs because the research says that it yields results," Gilliam said. "The truth of the matter is the cost-benefit analysis is on children who are at risk and need it the most, so you're basically undercutting your investment."

He added, "If there's ever a child who needed preschool, it's the kid who is kicked out of it."