Researchers from the universities of Cambridge, UK, and Lakehead, Canada, found that women earn less money than men the more the sexes share the same occupations.
The more women and men keep to different trades and professions, the more equal is the overall pay average for the two sexes in a country, a large-scale survey of 20 industrialised countries has found.
The researchers attribute the surprising results to the fact that when there are few men in an occupation, women have more chance to get to the top and earn more. But where there are more equal numbers of men and women working in an occupation the men dominate the high-paying jobs.
The research compared the degree to which men and women are working in different professions with the gap between their pay.
Pay was most equal in Slovenia, where women on average earn slightly more than men, and in Mexico, Brazil, Sweden and Hungary, where women earn almost as much as men on average. In these countries men and women work in different occupations to a greater extent than in many of the other countries the researchers looked at.
In other countries such as Japan, the Czech Republic, Austria and Netherlands, women are more likely to work in the same occupations as men, and the gap between their pay and men's is higher than average. The UK was higher than average among the 20 countries for inequality in pay.
The researchers, Professor Robert Blackburn and Dr Girts Racko, of Cambridge, and Dr Jennifer Jarman, of Lakehead, used statistics for each country on the proportion of women and men in each occupation, and the overall average gap in pay. They correlated these to show the relationships between workplace segregation of the sexes and the gap in their pay.
"Higher overall segregation tends to reduce male advantage and improve the position of women," the researchers said.
"The greater the degree of overall segregation, the less the possibility exists for discrimination against women and so there is more scope for women to develop progressive careers."
"For instance, within nursing men disproportionately fill the senior positions...but the fewer the number of male nurses, the more the senior positions must be filled by women."
"Perhaps our most important finding is that, at least for these industrially developed countries, overall segregation and the vertical [pay gap] dimension are inversely related. The higher the overall segregation, the lower the advantage to men. This is directly contrary to popular assumptions," he added.
The research has been published in the journal Sociology.