BERLIN: When Spanish Economy Minister Nadia Calvino found out she would be the only woman lined up for a photo call to promote the high-profile Madrid Leaders Forum last May, she walked out.

"We can no longer consider it normal that 50% of our population is not present," said Calvino, who months earlier had vowed to not attend events where she was the only woman, in protest at the lack of female representation in economics and business.

There seems to be a lot to celebrate on International Women's Day in the field of economics. Women head the International Monetary Fund, the World Trade Organization, the U.S. Treasury and the European Central Bank. However, more broadly women remain a small minority in a field that is still seen by many as being dominated by men in suits and churning out policy divorced from the real world.

"The pervasive underrepresentation of women in economics is systemic and structural," Ngozi Okonjo-Iweala, the first woman to head the World Trade Organization, told Reuters. "It is not just a matter of fairness but one of long-term global prosperity."

The Women in Economics Initiative seeks to advance gender equality in the discipline. According to its 2022 Index, women represent from 10% to 24% of the top global positions in economics, covering academia and the private and public sectors.

"There are no women in the textbooks and most big names in economics are men," said Sandra Kretschmer, economics researcher and member of the Women in Economics Initiative.

Friederike Welter is the head of the Bonn-based Institute for Small and Medium Enterprises (IfM) - the so-called "Mittelstand" sector key to Germany's export successes.

She said the lack of women in top economic roles in itself discouraged other women to choose the field as a career.

"When I became head of this institute, automatically we had way more applications from women," said Welter, who was appointed ten years ago and is now considered one of Germany's leading economists.

Janet Yellen, the first woman to head the Treasury and chair the U.S. Federal Reserve, makes frequent reference to the issue. At a banknote printing event last December she said more progress was needed.

It all starts early on. At university in both the U.S. and Germany women represent about a third of those studying economics.

The reasons are complex. Economics entails a lot of mathematics and analytical thinking and there is a cliché that men are better at those, which can make women reluctant to choose this discipline, said Katharina Wrohlich, leader of the Gender Economics research group at the German Institute DIW.

Guido Friebel, from the Goethe University Frankfurt, said another factor could be the culture. "There is an extremely competitive culture in economics, it's aggressive," he said.

Later, there is a "leaky pipeline" between junior and senior ranks. While 40% of the positions are filled with women at the PhD level and the level of assistant professors and lecturers, the share of women falls to 27% at the senior level, according to a global study by Goethe.

That has led to an over-concentration on some subjects at the expense of others. Women and men tend to have different research interests, said Alisa Weinberger, economics researcher at Goethe. Women are doing more research in health, labour and education, while men focus on economic theory, macroeconomics and finance.

"We need more women choosing economics as a major, but we also need to keep these young women in the field," Goethe Professor Nicola Fuchs-Schuendeln said. "Greater diversity would diversify the questions we ask as social scientists."

In the higher ranks of the public sphere, only one in 10 central bank governors is a woman and only 15% of finance ministers, the index of the Women in Economics Initiative shows.

Women have held just 12% of the top jobs at 33 of the biggest multilateral institutions since 1945, and more than a third of those bodies, including all four large development banks, have never been led by a woman, a study showed this week.

The World Bank is taking a proactive approach to create a more positive environment and remove obstacles for female economists, said Kathleen Beegle, lead economist in the Human Development Team of the bank's Development Research Group.

"Studies show women economists face a variety of hurdles in the profession, such as a lack of role models and a hostile work culture," she said. The World Bank's Research Group arranges mentoring opportunities and offers home-based work options to accommodate family care responsibilities, Beegle said.

Christine Lagarde, president of the European Central Bank, said in an event on Tuesday that more needed to be done.

"There are incredible opportunities that are wasted if women are left to the side of the economic road," she said.