A dramatic pay gap emerges between women and men in America the year after they graduate from college and widens over the ensuing decade, according to research released on Monday.
One year out of college, women working full time earn 80% of what men earn, according to the study by the American Association of University Women Educational Foundation, based in Washington D.C.
Ten years later, women earn 69% as much as men earn, it said.
Even as the study accounted for such factors as the number of hours worked, occupations or parenthood, the gap persisted, researchers said.
"If a woman and a man make the same choices, will they receive the same pay?" the study asked. "The answer is no. "These unexplained gaps are evidence of discrimination, which remains a serious problem for women in the work force," it said.
Specifically, about one-quarter of the pay gap is attributable to gender -- 5% one year after graduation and 12% 10 years after graduation, it said.
One year out of college, men and women should arguably be the least likely to show a gender pay gap, the study said, since neither tend to be parents yet and they enter the work force without significant experience.
"It surprised me that it was already apparent one year out of college, and that it widens over the first 10 years," Catherine Hill, AAUW director of research, told Reuters.
Among factors found to make a difference in pay, the choice of fields of concentration in college were significant, the study found. Female students tended to study areas with lower pay, such as education, health and psychology, while male students dominated higher-paying fields such as engineering, mathematics and physical sciences, it said.
Even so, one year after graduation, a pay gap turned up between women and men who studied the same fields.
In education, women earn 95% as much as their male colleagues earn, while in math, women earn 76% as much as men earn, the study showed.
While in college, the study showed, women outperformed men academically, and their grade point averages were higher in every college major.
Parenthood affected men and women in vividly different ways. The study showed mothers more likely than fathers, or other women, to work part time or take leaves.
Among women who graduated from college in 1992-93, more than one-fifth of mothers were out of the work force a decade later, and another 17% were working part time, it said.
In the same class, less than 2% of fathers were out of the work force in 2003, and less than 2 percent were working part time, it said.
The study, entitled "Behind the Pay Gap," used data from the U.S. Department of Education. It analyzed some 9,000 college graduates from 1992-93 and more than 10,000 from 1999-2000.