This year marks the centenary of International Women's Day, originally created as part of the larger campaign for equal rights and opportunities for women. A century later, tremendous progress has been achieved in gender equality, access to political rights, education and employment for women around the world. A US Census Bureau report found that in 2009 women had pulled ahead of men in the attainment of higher education; women represented 58% of the surveyed population holding bachelor's degrees and advanced degrees. But despite these encouraging gains, women continue to earn considerably less than their male peers in the same educational category, including in STEM (science, technology, engineering and mathematics) occupations. For example, a 2008 study in the US found that although female biology scientists represented 53% of workers, their earnings only translate to 89% of the wages earned by men in these occupations. Two reports published in 2010, the AAAS/L'Oreal survey on roadblocks faced by women scientists to career progression and a report by the American Association of University Women (AAUW) analysing the under-representation of women in STEM professions, also offer a sobering counterpoint to the more optimistic news about women's gains in higher education in the US.

Of the 1,300 male and female respondents in the AAAS/L'Oreal survey, both groups cited the scarcity of jobs and funding resources as important barriers to career development, and a high proportion of both groups (83%) knew of a colleague who had left science. Struggling with career-life balance and the challenges of having and raising children while maintaining a scientific career emerged as two key reasons causing women to leave science. Rather disturbingly, an astonishing 52% of women also reported having experienced gender-related bias, compared with 2% of male respondents. These findings regarding the particular challenges faced by women in STEM professions are echoed in the AAUW report.

So, what are the solutions for improving the retention rate and providing more equitable pay for women in science? Both reports found that mentorship and a supportive environment created by colleagues and peers can be an important factor in job satisfaction for women scientists. Recommendations in the AAUW report also emphasize a need for clear, transparent frameworks for evaluating performance and success, and an awareness of one's implicit bias. An earlier report by the AAUW on the gender pay gap suggested that some proportion of the pay gap may reflect the relative willingness of women and men to negotiate for competitive salaries and recommended better training for women scientists in negotiation strategies. The pay gap is often exacerbated for women who take career breaks to have a family. Flexible working practices, including in high-level positions, and other policies that aim to strike a better balance between career and family could potentially help reduce the pay gap and retain women in science.