Almost 50 years after it became illegal to pay women less than men, women still face lower wages and fewer managerial opportunities than men during the past decade, says a new study.

Female managers earned 81 cents for every $1 earned by male managers in 2007, up 2 cents from 79 cents in 2000, according to the Government Accountability Office report released Tuesday.

"What is most startling to me is how little progress we've made even though there's a bright spot in that more women are gaining education, we're closing the education gap but we're not closing the pay gap," Rep. Carolyn Maloney, a New York Democrat, said at a hearing of Congress's Joint Economic Committee. 

The study — called "Women in Management: Analysis of Female Managers' Representation, Characteristics, and Pay," — also found that women in 2007 made up 40 percent of managers and 49 percent of nonmanagers in 13 industries that account for most of the U.S. workforce. In 2000, the breakdown for women was 39 percent managers and 49 percent nonmanagers. Women's average salaries were $52,000, compared with $75,000 for men. (In general, women earn $11,000 a year less than men who do the same work, says NOW. That's anywhere from $400,000 to $2 million over a lifetime.)

In all but three of the 13 industries studied, "women were less than proportionately represented in management positions than non-management positions in 2007," the report said. The sectors where female managers were better represented: construction, public administration, and transportation and utilities.

Women with children had lower salaries than those without: Mothers earned 79 cents for every buck a man took home in 2007, but childfree women earned 83 cents for every dollar a man earned.

"We found that being a mother was associated with lower pay," Andrew Sherrill, director of education, work force and income security for the GAO, said at the Joint Economic Committee hearing.

Delia Passi, founder of WomenCertified, a Florida-based training company that helps firms sell to women, attributed the pay gap to stereotypes and differences in negotiating tactics.

"When a man goes to negotiate it's almost expected, appreciated and valued in business," Passi told the South Florida Business Journal. "When a woman is offered something, we are gracious, and we don't look at that as a form of negotiation."

Because the GAO wanted to "avoid concerns about the role of the recession that began" in December 2007, the study focused on the period before that. The report included women and men working at least 35-hour weeks for 50 weeks a year.

A bill to address the gender pay gap has stalled in the Senate. Among other things, The Paycheck Fairness Act would make it easier for women who allege discrimination to file class actions against their employers. The act – which was passed by the House in July 2008 and again in January 2009 – also removes caps on punitive damages in pay-discrimination suits.