7 Year old Summits in a Day

Now.. I know that this tends to be quite a controversial topic of conversation... but I'd like to ask "how young is too young"? Not from a moral or ethical or bad parent stand point... but to all those medical people out there.

I gave birth to my BoyChild while I lived in Colorado. I had wanted to go up Pikes Peak (14,110 I believe)and was warned by doctors that it was inadvisable to take either of my children to the summit because their bodies weren't equipped to deal with the thin oxygen.(GirlChild is about a year older then BoyChild.. so they were both very young when we lived in CO. We moved when they were two and three).

So... People with medical experience... in your PROFESSIONAL opinions... what do you think? How young is too young?