It’s no secret that sex inequality still exists in science. Despite efforts to narrow the gap, disparities still exist in hiring, earnings, funding, and publishing. An analysis of over 5.4 million research papers, released this week in the journal Nature, confirms that women are significantly underrepresented in academic publishing worldwide.

The authors reviewed papers published between 2008 and 2012 that were indexed in the Thomson Reuters Web of Science database, analyzing them for the relationship between gender and research output, collaboration, and scientific impact. They found that globally, women account for fewer than 30 percent of authorships. The extent to which men dominate scientific production varies by region, with fewer than six percent of countries coming close to achieving parity.

South American and Eastern European countries exhibited the greatest gender balance, while the most male-dominated countries were largely in the Middle East. Only nine countries had a higher number of female authorships than male authorships, and only five of these countries produced more than 1,000 articles in the analysis. The US states and Canadian provinces that were closest to achieving parity have something in common with these countries: they have relatively little scientific output.

Women are also much less likely to be listed in the prestigious first and last author positions. For every article with a female first author, there are nearly two articles first-authored by men. Women are also significantly less likely to produce single-author papers. When women are the first, last, or sole author on a study, the paper attracts fewer citations than when a man has one of these roles.

The 50 most productive countries in the analysis account for 97 percent of the total publications; within those countries, female collaborations were more likely to stay within the national borders than men’s. This can hurt their publishing portfolio, as international collaborations can generate extra citations.

The study also found that "care"-related fields such as nursing, midwifery, education, and social work were dominated by women, while men dominated fields such as engineering, robotics, aeronautics, and high-energy physics. Women publish significantly fewer papers in areas of research that require expensive equipment, such as high-energy physics.

This isn't the first study to identify funding as a significant barrier to equality between the sexes. A 2012 study in PLoS ONE examined the issue in the United States and found that lower publication rates of female faculty are correlated with the resources needed for the research within the discipline. Certain areas, such as molecular biology, are resource-intense, and this compels researchers to compete against each other for finite grant money—which may be part of the problem. Historically, female faculty members have received less institutional support and have less access to research resources than their male counterparts.

These funding discrepancies don’t just exist in the United States. A study published this week in the online journal BMJ Open found that in the UK, female scientists had fewer studies funded and received less funding than men across most areas of infectious disease research. Of the 6,052 studies funded between 1997 and 2010, 72 percent of grants were awarded to men, men received the bulk of the total investment, and the median value of a grant awarded to men was higher. These differences remained broadly unchanged over the 14-year study period.

Many of these trends can be explained by the under-representation of women at senior levels of academia, note the authors of the Nature study. Despite existing policies meant to level the playing field, local and historical forces still act as barriers to women’s advancement in science. In order to address these issues and create effective policies, each country must carefully take into account the social, cultural, economic, and political factors that contribute to maintaining the status quo.

“No country can afford to neglect the intellectual contributions of half its population,” they conclude.

The study was accompanied by Interactive graphs of global disparities in science.

Nature, 2013. DOI: 10.1038/504211a (About DOIs).