Women may be under-represented in high-powered careers in areas such as business and science because they shy away from taking advanced maths courses at school, research suggests.
A new study concludes that teenage girls are not put off the subject because of a lack of reward or because they do not have the ability. Instead, the deterrent is inflexibility in courses and curriculum.
The paper, published in the June 2016 Economic Journal, is based on an analysis of Danish administrative data covering three groups of students whose education and careers have been followed since they started high school in 1984-86.
The study included a pilot scheme that randomly allowed students to take a more flexible combination of advanced maths and other courses rather than a restrictive bundle of courses.
It found that only one in 10 girls picked advanced maths before the pilot scheme, but this doubled after the initiative was introduced.
More boys also chose these courses, rising from four in 10 before the pilot to half afterwards.
The study also concluded that students who did take advanced maths qualifications earned 30% more on average and had higher career achievements.
For both genders with identical abilities in maths, the wage gain from studying the subject was equal.
The researchers went on to note that only the girls with the highest abilities chose maths, while boys who had a lower ability were willing to pick it.
This means that there is a pool of girls who would gain from taking advanced maths, the study says, and more could be encouraged to do so by introducing further flexibility into the curriculum.
"Changing the learning environment and designing the curriculum to identify and foster girls with high mathematical abilities would attract more girls and reduce the gender pay gap," the paper says.
The researchers, Juanna Schroter Joensen, of Stockholm School of Economics and the University of Chicago, and Helena Skyt Nielsen, of Aarhus University, also say: "If girls choose advanced maths and science courses in school, they are paid as much as comparable male colleagues for these qualifications.
"But somehow the costs embedded in the educational environment discourage girls from going for these qualifications - despite them being paid well for doing so."