TUESDAY, Sept. 3 (HealthDay News) -- There's still a significant gap between the average incomes of male and female doctors in the United States, even though women have made major strides in the profession over the past quarter-century, a new study finds.

Seth Seabury, a research associate professor at the University of Southern California, and his colleagues examined statistics from 1987 to 2010 for 1.3 million workers. The study authors estimated how earning gaps between men and women had changed for nearly 6,300 physicians, nearly 32,000 other health-care workers and employees overall.

The percentage of physicians surveyed who were women grew remarkably, from 10 percent between 1987 and 1990 to 28 percent between 2006 and 2010. But women's salaries didn't improve statistically compared to those of men over that time period, the study found.

"While it is important to study gender differences in earnings after accounting for factors such as specialty choice and practice type, it is equally important to understand overall unadjusted gender differences in earnings," the study authors wrote. "This is because specialty and practice choices may be due to not only preferences of female physicians but also unequal opportunities."

The study appeared online Sept. 2 in the journal JAMA Internal Medicine.

More information

To learn how women changed the face of medicine, go to the U.S. National Library of Medicine.