I can honestly say that during the past year, I've never worked so hard in my life. With three kids under the age of 7 and a demanding full time job, I'm on from 6 a.m. to at least 10 p.m. most days. And then there are the 3 a.m.wake up calls on the nights when my four-year-old has his  "Dr. Giant" dreams.

But research shows that having kids tends to hurt a mother's earning potential.

According to University of Massachusetts, Amherst Professor Michelle Budig, mothers earn 60 cents for every dollar a father earns, information she shared while testifying before Tuesday's Joint Economic Committee.

Tuesday's hearing  focused on the findings of a new GAO study  that looked at women in management. Just 40 percent of managers were women in 2007 and earned 81 cents for every dollar a man made.That's a slight increase from 2000, when women made 79 cents on the dollar. But in seven years, mothers managers didn't shrink the pay gap by even a single penny.

The GAO said that it couldn't pinpoint why the pay gap and the child penalty exist, nor say for certain whether discrimination is the culprit.

But the fact that more women tend to opt for flexible work arrangements, less demanding careers, part time work, or periods of non-paid work to care for children undoubtedly comes into play.

This isn't the first study to note a mommy penalty, or a  "mom bomb," the catchy phrase used by Congresswoman Carolyn Maloney (D-NY).

There's the 2003 GAO study that found women tend to earn less once they have kids, while having kids tends to increase a man's pay. Being called "Daddy" increases a man's earnings by 2.1 percent while Mommy's earnings drop by 2.5 percent.

There's this March 2007 study from Cornell University that says the the per-child wage penalty is actually five percent. That certainly won't make affording college tuition any easier.

Women earning less is an issue that carries into retirement as well. Fretful study after study shows how women are less prepared for retirement. If you earn less, you probably have less money to sock away. And part-time or freelance work rarely comes with 401(k) matching money.

The findings really don't surprise me. Question is, what, if anything, should be done about it?

And has the concern about success at work and success with family influenced any of you to choose not to have kids, such as the women in the Tuesday's Variety section story "Rising Trend: Not Bringing up Baby"?