Hayden Panettiere -- Childbirth Ruined Parts of Me

Hayden Panettiere can't escape the laws of physics -- birthing Wladimir Klitschko's baby did some permanent damage to her bod.

Hayden copped to the ordeal of bringing Kaya Evdokia into this world with People ... saying, "I'm limping around. I'm still trying to figure out what [pregnancy] has done to my body, how it's changed it."

As for recovery ... she added, "I know some things will never be the same again."

Sounds about right -- Kaya was 7 lbs., 14 oz. and damn near 2 feet tall. Hayden's only 5 feet tall.