Old enough to be a parent.
Not old enough to be a grandparent.

I was a parent at 18. I wouldn't consider that middle aged.

I think what TheRoad meant was, you're old enough to have kids who are maybe teens or a little older, but you aren't a grandparent yet.

Probably, though I think many people become grandparents when they are middle aged. My mother was a grandparent in her mid-40's. My oldest son is 24 now and I'm 42, so I'll probably be a middle-aged grandparent as well.

Middle age is that difficult period between juvenile delinquency and senior citizenship when a fellow doesn't know which generation to complain about.

Middle age is when work is a lot less fun - and fun a lot more work.

Middle age is when your wife gives up sex for Lent, and you don't know till the 4th of July.

Middle age is when broadness of the mind and narrowness of the waist change places.

Thank you.

I made a general response. Many people have kids in their late 30's and up so they can be middle aged and still have kids that are in grade school.

Yes teenagers can get pregnant and some do when they are still teenagers. Know one would call them middle aged

There is no exact age for being middle aged. Becoming a parent when a minor or becoming a parent when old enough to collect social security will not make them middle aged.

Another way to define middle age is that people that are under 30 are young. At 29 people can still say they are in their 20's. Once they hit the big 30 they are not young any more. At 30 time to be mature, responsible, productive adults. Because a 50 year old acts like a 20 year old it does not make him young. People of 60 are old. The span in between the middle group of years, the 30 to 59 year olds are middle aged.

Though as you can see those that live to be only 62 their last third of their life defined by a title was not truly one third of their life.

Also when people wish they could start their life back over they say if I could be in my 20's again with what I know now. Notice people do not use the age of 30's or above in that phrase. So another way to support that middle age starts at 30. And they say that phrase once they hit 60 because their retirement plans and or state of health are no where near what they will need to get them through the last third of their life no matter how many years past 60 maybe left.

It can be suggested middle age is a state of mind. No one past 60 is middle aged no matter what they think, do, say, act, or even if they still, simply look marvelous.

Here is the best answer I was able to find:

http://en.wikipedia.org/wiki/Middle_age

I think of the word middle...or the concept of halfway.

If I live to be 90, then 45 is the middle.

Then again I have spent a lot of time with small children so I tend to be literal.

I am with you, Mozilla! That is how I have always viewed middle age.

Technically, I think this is true. The only problem with it is, we have no idea how long we're going to live. So we won't really know what our individual "middle age" was until after the fact.

But in general, I think the 40's to mid-50's would cover it for most people.