The study, published in the Mayo Clinic Proceedings, suggests women are underrepresented in research focusing on significant health issues unrelated to reproduction.

Wendy Rogers and Angela Ballantyne of the School of Medicine at Flinders University in Adelaide, Australia, said that at first, the numbers in the 400 clinical studies -- all conducted in Australia and published in journals between Jan. 1, 2003, and May 31, 2006 -- did not show women as underrepresented. Of the 546,824 persons in the studies, 73 percent are female.

However, a closer look shows the numbers are larger due to the greater number and size of female-only studies dealing with reproduction.

In research in which men and women both participated, male participants were more than three times as likely to be involved. Other data provided by the Australian researchers indicated that gender-specific results reporting is particularly lacking in pharmaceutical research.

"Research on women's health continues to focus predominantly on their reproductive capacity and function, whereas research with men continues to investigate conditions that are not specific to one sex," the study authors said in a statement.