Just curious about this. We adopted a sweet little Manx kitten a couple months ago from the humane society. She's active, healthy and playful, but she's very small. She only weighs 3.5 lbs, but she is even a little chubby if anything! She's a stockier, shorter kitty, but is very small at 5 months old. I'm just curious, does spaying at a young age (12 weeks in this case) have anything at all to do with growth and maturity?