This is for all those parents, mothers in particular, who have been counting down the days until your son or daughter leaves the proverbial nest: It will never happen.

At least according to scientists at the Tupper Research Center, children will live within their mother for the rest of her life in the form of fetal cells.

Previously, common thought was that once a child was born, the son or daughter took everything with them, including all their cells. They were separated from their mother for the first time, taking all their "baggage" with them. And in another 18 years or so, the son and daughter would pack up and leave with all their "baggage" yet again.

Now, researchers have discovered that the case isn't that simple. It seems that a baby's cells linger in a mother not just for a short time after delivery or even for a few days or weeks, but perhaps the rest of her life, according to a story on National Public Radio.

During blood tests, researchers have been finding large quantities of fetal cells mixed in with the mom's blood. Not just a couple cells here and there, but hundreds and thousands of the cells floating around. They find the cells especially prevalent at diseased sites within a mom's body.

And a woman doesn't have to carry the baby the full nine-months to maintain those fetal cells in her body. The fetal cells remain in a mom even if she's had an abortion or a miscarriage; she still carries those cells around for the rest of her life.

But then we must ask the big question: What are those cells doing in a mom's body? Now that these scientists have discovered the cells, they are trying to figure out if these cells are doing something while floating around in their mother's bloodstream.

In particular, are these cells protecting their mother, perhaps for the rest of her life? Scientists are trying to figure out if these cells can help fight off sickness, by turning themselves into whatever disease fighting cells are needed. If this proves to be true, moms can thank their children for those extra years of healthy living.

Realizing that this idea could be to good to be true, these same scientists are also testing a couple of other hypotheses.

An alternative would be that these cells gather at the inflammation sites in a mother and contribute to a mom's auto immune disease.

This case would be labeled "Cells Gone Bad." If this idea holds true, then moms can lay even more guilt on their children if they get sick.

Of course, there is one final idea being floated about: The cells stay in a mother's body ... and do nothing. The cells just float around the body, hanging out, doing whatever it is that pointless cells do in a body and perhaps rubbernecking at sites where mom does get sick.

While everyone would like to believe the first hypothesis is true, the scientists admit that it's still too early to know if these fetal cells are actually repairing their moms. But there's more and more evidence that the "good hypothesis" is likely correct.

Which brings us to the question: If you have more kids, do you have more of these fetal cells floating around in your body, wandering around hopefully trying to help out?

If this is true, those of us who have moved beyond --way beyond -- the average of 2.3 kids must be bursting at the seams with fetal cells. If the "good theory" holds true, I should live to be about 123 at a minimum.

Even if the good theory proves correct and moms are able to avoid some forms of illness thanks to their kids' cells, scientists must take into account other factors which may lead to a decrease in a mom's health such as stress, lack of sleep, frustration after picking up winter coats for the fourth time in a day.

Hopefully, it all just balances out in the end.

-- As a mother of five, Ronda Graff is always looking for any theory which will keep her healthy -- at least for a day or two in a row.