Baby animals spawn outside of fence frequently

What I expected to happen was...:
All animals spawn inside fenced in area when the world is loaded.

What actually happened was...:
Lots of baby animals escaped the fenced in area (fence is even 2 high)

Steps to Reproduce:
1. Put various animals in a small fenced in area(7by7? fence CAN be more than 1 block high).
2. Breed them with wheat.
3. Wait until breeding has finished and all baby animals have spawned.
4. Log out of the world and back in.
5. Lots of baby animals are outside of fenced area.