Female doctors earn an average of $56,000 less each year than male doctors, according to a new study, which found that gap hasn't budged since the late 1980s.
Researchers used a nationally-representative survey conducted in 1987 through 2010 and found that although earning gaps shrank over time among non-healthcare workers, that was not the case for doctors and certain other health professionals.
"There is something that's intrinsically going on within the physician workforce," Dr. Anupam B. Jena, the study's senior author from Harvard Medical School's Department of Health Care Policy, said.
"We would have suspected that the gender gap between males and females would have converged somewhat over the years, and what we found was that it was relatively constant."
He and his colleagues compared survey answers about income and other aspects of work from close to 6,300 doctors and 32,000 other healthcare workers.
Taking into account hours worked and years of experience - but not specialty - they found the average male doctor earned about $221,000 in 2006 to 2010, and the average female doctor earned $165,000.
That worked out to about a 25 percent difference in salary, similar to the 20 percent disparity Jena and his colleagues found among doctors surveyed between 1987 and 1990.
Income gaps held steady at about a 40 percent difference in pay among male and female dentists. Disparities fell slightly over time to about 11 percent for pharmacists and 6 percent for registered nurses, the researchers reported in JAMA Internal Medicine.
During the same time period, they found salary differences between men and women outside of healthcare dropped from 28 percent between 1987 and 1990 to 15 percent between 2006 and 2010.
The findings echo another recent study showing female doctor-researchers make less money than their male counterparts, on average.
Jena said some of the income differences between doctors might be explained by women working smaller caseloads or by more men practicing in higher-paying specialties. But implicit biases could prevent women from entering those fields in the first place, he said.
"It could very well be the case that male and female pediatricians and male and female surgeons earn the same amount of money. But if it's more difficult for females to enter surgery, then their access to higher-paying fields would be lower," Jena, also from Massachusetts General Hospital in Boston, told Reuters Health.
"Whether we call this discrimination or bias … I think that's probably some component of it," he said.
Although that "is probably true to some degree," said Anthony Lo Sasso, a health policy and economics researcher from the University of Illinois at Chicago, there is likely less bias keeping women from entering certain specialties than in the past.
"It's hard to say that that's a driving factor," Lo Sasso, who wasn't involved in the new research, told Reuters Health.
He said it's possible more women choose flexibility and fewer on-call hours over a higher salary, for example.
"I view that as the big question that remains unanswered: what can we really say about how much of this is a choice that physicians are making, a willing trade-off between making more money and having a more reasonable balance of work and life?" he said.
"I think it really gets at whether we want to label this difference as a problem or not."
Jena agreed. "If opportunities are equally accessible, and women continue to choose certain specialties because of lifestyle reasons, that's totally fine," he said. "But we have to make sure those opportunities exist."