Baby Boom is a member and occasional leader of the Helix, a team of six metahumans resulting from the genetic engineering process of Dr. Amos Love. Love raised them in isolation and most of their knowledge of the world can be traced to books, radio, and television. Baby Boom is an adult whose body stopped aging when she became five years old. Her powers allow her to explode anything in her general vicinity with the power of her thought.
Batman Animated Series
Baby Boom's origin was later revamped by the Batman Animated Series. Baby Boom was renamed as Baby Doll and her ability to explode anything with her mind was dismissed entirely.
After Mary's failed attempt at achieving her former fame and glory, she was put through a rehabilitation program at Arkham and was released a year later. The Wayne Foundation gave Mary a steady form of employment by making her an innkeeper at one of Gotham's romantic getaway spots. Unfortunately, Mary's alter ego was beginning to settle back in when a tenant at the inn harassed her about her former life as an actress. Mary's sanity takes an even deeper plunge when she falls for the sob story that Killer Croc was giving during his sentence hearing.