Not human babies. Humans are a creature with only 1 HD, which means that they will never actually have a type-based HD. At any point in a human's life, including the baby stage, they will possess at least one class level in either a PC or NPC class.
I feel like if Baby were a printed class it would be made by Paizo, which isn't allowed in this discussion.
"Movement speed is the most important statistic in this game."
"Give them no mercy for they give no mercy to us."