becoming a mother

My daughter who is 12 asked me the other day at what age is the best time to to become a mother. I told her that it is best to have the first baby before she is 30 years old.Anyway, I have to confess to her that I couldn't follow my own advice. I had both kids after 35 years old because of circumstances. But then I wonder whether my reasons to be a mother are entirely selfish. Thank God that my kids are born normal and healthy at 7 lbs 3 oz and 8 lbs 13 oz!