I agree... it's one of the reasons we didn't have a 7th child. Sure, I'd love a baby (or a toddler), but the young-adult stage is emotionally hard - and my kids aren't rebelling terribly or falling off the deep end with life. I'll already be in my 50's & my dh will be in his 60's when our youngest hits this stage - I can't imagine doing as I get even older.
But, the thing is... I don't feel I can adequately say something to young mom's who want a lot of kids. It just feels so anti-family.