How old is to old??

Taneshia • I am pregnant with my third child and it was a complete surprise!!
I was wondering how old is to old to have a baby? 
Times have changed so much and it seems that now you can never be to young to start a family (not my opinion). So how old would be to old? Take into account that people are in fact living longer and healthier lives (in some cases) but would it be silly to start a family in ur mid to late 40s knowing that at 60 ur child may only be 14-16 and by the time they have kids you could be well into ur 80s? 
I just wanted to see how other viewed  it.. Please no "it's there life, they can do what they want" comments. We already know that.. I just want to see what people's personal idea of to old would be?