I've been taking my almost four year old son since birth. He LOVES going and YES and alignment will help with bowel movements. In fact that was one of the first things my doctor said to me. He said "be prepared." :)
Now my son freaks out if drive PAST the chiro. He points and yells at me "go back mom, we need to go see Dr. Don and go on the table." In fact my son ranks seeing "Dr. Don" up with going to Chuck E. Cheese!
Seeing a chiropractor has basically given me my life BACK. I was in so much pain I was miserable all day long and never slept very well. That's all changed in the last five years. It also helped me lose that baby weight because I could go back to working-out and not be in pain.
Try it out! You'll love it.