All damage dealt to you by Mom herself will result in a full heart of damage. The stomp can easily be avoided by just moving out of the way. The stomping attack will always be telegraphed by a large shadow appearing on the ground where you happen to be standing. Mom deals damage by either hitting you with her hands, if you get too close to the doors, or by stomping down with her foot. With one champion version of Mom, the eyes will fire out tears. This will spawn enemies in front of them.
In the room, there will be a doorway on each wall through which Mom's eye/s, hands, and portions of her body will poke themselves out.
Avoiding them as well as her is usually what causes the problems. Mom as a whole isn't particularly difficult, but the fight can become troublesome as she spawns other enemies to fight against you. The first of the bosses is always fought on the second floor in chapter three.
