I am 23 years old and I have Keratosis Pilaris. I was diagonosed at 16 but didnt start getting symptoms until about age 13.
It is genetic so it is likely that my daughter will have it also.
Every one says you grow out of it...I'm not sure about that yet as I haven't hit my 30s.
I exfoliate my arms (I have it mostly on my upper arms and forearms) in the shower with a loofa. Then I apply hydrocortison cream after I get out of the shower. The sun does lessen the appearance of KP bc it is basically a build up of keratin in the skin and the sun exposes your skin to the keratin. In the winter my arms look especially bad, red, raw looking, and little bumps covering them. In the summer the redness goes away and i just get a few bumps here an there.
I know you cant really take a baby out and let him/her sit in the sun but I just wanted to let you know that there are ways to lessen the appearance of it as your child grows.
My advice to you would be to not make your child extra aware of it as he/she grows older. I have a nasty habit of picking at the bumps ever since I was diagonsed with it and it leaves my skin very very red and blotchy. So try not to make a big deal of it and maybe he/she wont even notice it to much.