An increasing number of young female physicians are becoming anesthesiologists, but the pay of those women lags behind their male peers, even after accounting for differences such as hours worked and experience, according to a new RAND Corporation study.

Marital status played a more important role than children in driving gender differences in hours, as married female anesthesiologists worked significantly fewer hours than their male colleagues regardless of whether the anesthesiologist had children, according to findings published in the online first edition of Anesthesiology, the official journal of the American Society of Anesthesiologists®.

Research in the field shows there is a wage gap between men and women across all medical specialties, not only anesthesiology. Additional research may need to be done to understand how and why women are choosing certain types of work environments.

"With more women entering the anesthesiology workforce, there are possible policy implications for the overall management of the anesthesiologist workforce, including employment arrangements at hospitals as well as within anesthesiology practices," said Lindsay Daugherty, co-principal investigator of the study and a policy researcher at RAND, a nonprofit research organization. "Female anesthesiologists may demand more flexible or regular work hours to accommodate family responsibilities."

The RAND study analyzed a 2013 survey of members of the American Society of Anesthesiologists that found 40 percent of anesthesiologists under the age of 36 were female, a substantial increase over 2007 when 26 percent of young anesthesiologists were women.

Despite an increasing number of women in the medical specialty, the study found that male anesthesiologists earned 29 percent more than female anesthesiologists, with a reported average annual income of $403,616 for men compared to $313,074 for women. The national average wage gap between men and women across all occupations is 23 percent.

Accounting for experience, employer type and hours worked reduces the wage gap from 29 percent to 7 percent, which explains most, but not all, of the gender differences in earnings for male and female anesthesiologists.

Female anesthesiologists worked approximately six fewer total hours and four fewer clinical hours per week compared to male anesthesiologists. In addition, female anesthesiologists were nearly three times as likely to work part time, defined as less than 35 hours a week.

When researchers adjust the pay estimates based only on hours worked, the male anesthesiologists earned more than their female peers -- $151 per hour compared to $131 per hour -- a wage gap of 13 percent.

The survey further reveals that female anesthesiologists have different employment and compensation arrangements than male anesthesiologists.

Female anesthesiologists were 44 percent more likely to be employed by one hospital and 22 percent more likely to work in a single facility, such as a surgery center. While female and male anesthesiologists both received approximately 10 percent of compensation from bonuses, female anesthesiologists were more likely to be employees who received a fixed salary and less likely to receive compensation from fee-for-service arrangements, where earnings are based on the number and type of services provided.

RAND researchers note that if female anesthesiologists are working fewer hours than male anesthesiologists, then hospital administrators may need to explore solutions to optimize surgical workflow, such as adjusting staffing schedules, changing triage practices or hiring more anesthesiologists.