I bred my bitch for the first time when she was 4 and I was surprised how much her head changed after having her puppies! Did the pregnancy and whelping change her head or would her head have changed anyway? Her nose pigment is also much darker since having puppies and doesn't fade as much in the winter anymore. Pregnancy related or were the changes going to happen anyway? I'm not complaining just surprised and if the pregnancy did cause it, why? Hormones are elevated in a dog if they are pregnant or not.

I find my bitch's heads change after their first heat cycle but not after whelping. Their coats get better after whelping though!

Most of my bitches heads grow after a heat and more after a litter. You're not imagining it and I doubt it would have happened anyway at 4.

I find the girls develop more with each litter, especially in broadness of her head. I also notice more depth of chest and forechest after a litter.

I've never seen nose pigment darken at that age but be happy your girl overall improved alot with her litter. I hope you got some pretty pups as well.