0938 GMT March 25, 2019
That's the finding of research analyzing the names of authors listed on millions of scientific papers, according to bbc.com.
Physics, computer science, maths and chemistry had the fewest women, while nursing and midwifery had the most.
Without further interventions, the gender gap is likely to persist for generations, said scientists from the University of Melbourne.
Dr. Cindy Hauser added, "Of the gender-biased disciplines, almost all are moving towards parity, though some are predicted to take decades or even centuries to reach it.”
The researchers used computer methods to analyze the genders of authors listed in databases (PubMed and ArXiv) containing thousands of scientific papers published over the past 15 years.
They found that 87 of the 115 subjects examined had fewer than 45 percent women authors.
Women are increasingly working in male-biased fields such as physics (17 percent women), while men are increasingly working in female-biased fields such as nursing (75 percent women).
However, forecasts suggest it will take a very long time to close the gender gap in some fields, with predictions of 320 years for nursing, 280 years for computer science, 258 years for physics and 60 years for mathematics.
The researchers said practical measures are already known that could help close the gap, including reforming publishing, ensuring women receive equal resources at work, greater recognition of demands outside the workplace that traditionally fall on women when assessing achievements, better access to parental leave and career breaks and equal access to informal professional networks.
Dr. Luke Holman said, "The solutions are out there but it's difficult to bring about change and get people to act on them.
"We haven't acted on them enough because it's difficult to change the way that people have always done things and it's maybe not afforded as high a priority as it should be by people in positions of power in the scientific industry and academia."
The researchers also looked at variation across countries.
They found a larger gender gap in Japan, Germany and Switzerland and a smaller gender gap in some European, African and South American countries.
The research was published in the journal PLOS Biology.