Having kids for your old age is NOT a good reason. I know too many old people who's kids have nothing to do with them. It's possible to have a life with friends or pets. I don't think kids are that much comfort sometimes, to say nothing of the financial aspects of having kids.
My sister had her first son at 40 and now I think sometimes she wishes she hadn't (he's 5 now) He turned out to be a REAL handful and she's just starting in on the school years. Also, she and her husband should be saving for their retirement and now they'll have the expenses of raising a child for the next 16 years at least.
