Women earn about half of life science doctorates, but only 21% of them land full professorships and a mere 15% serve as department chairs at medical schools. Two studies, currently under peer review, explored women’s early career advancement by looking at gender differences in publications and research funding. One found that women had a 10-15% higher likelihood than men of earning prestigious first authorships, on average, across more than 100,000 articles published between 1985 and 2009. However, women have remained substantially underrepresented in the senior last author position during the same time. The second study found that women are less likely than men to attain important R01 grant funding, crucial for transitioning to a senior scientist position. Both studies suggest that women face real barriers to advancing in the life sciences, and these are apparent early on in their careers.

According to the U.S. National Science Foundation, women earn about half of the doctoral degrees in science, yet they represent a mere 21% of the faculty at the full professor level at research institutions in the United States.

In explaining these numbers, a great deal of attention has been given to the “glass ceiling” – the idea that women reach a level near the top of their organizations beyond which they simply cannot advance. But women often meet barriers well before they have climbed to the upper echelons.

Our research focused on the advancement of women in the academic life sciences, chiefly biology and medicine. Similar to science more broadly, women earn about half of life science doctorates, but only 21% of them land full professorships and a mere 15% serve as department chairs at medical schools, for example. This under-representation at the senior levels is surprising, because we found evidence that women, on average, may perform better than men in the early stages of their careers.

Many have attributed the lack of senior women scientists to a “leaky pipeline,” in that women leave the field more frequently than men at every career stage. This view, however, obscures the fact that many women stall on the life sciences career ladder early on. For example, women make up only one-third of associate professors (the approximate equivalent of middle management) in academic medicine. This suggests that about 10 years after entering the profession, many have not advanced. (While these statistics don’t necessarily mean women leave the field – for instance, they may stay in lower-level positions – the academic life sciences are an up-or-out setting, and it’s hard for scientists to have a “career” without clearing the necessary hurdles, such as becoming an associate and then a full professor, and winning grants to fund their research.)

We explored why many women aren’t advancing in their early careers by looking at gender differences in publications and research funding. We have two studies that are currently under review at scientific journals.

Our first study, in collaboration with Dr. Carolin Lerchenmueller from Massachusetts General Hospital and Harvard Medical School, examined the rate at which women earn first author or last author positions on academic articles from U.S.-based laboratories. These authorships are key performance indicators in the life sciences. A first authorship, usually allocated to the leading junior author, signals that the researcher led the team in performing the research and in writing the manuscript. Last authorship, by convention, goes to the senior principal investigator who funded the research and who may have conceived of the project.

Previous research has counted the number of prestigious authorships by men and women and found that women are underrepresented in both positions. But that approach confounded women’s rate of earning prestigious authorships with their participation in medical research. It did not account for the fact that men still represent the majority of life scientists. Not considering how many women and men were eligible for these authorships can give a misleading picture of women’s success in science.

To address this issue, we estimated the relative likelihood of earning prestigious authorships for women versus men. (We divided the rate at which women received first and last authorships by the rate at which men received them.) This measure accounts for the fact that there are fewer women than men doing research in the life sciences, and that women tend to publish a little less frequently than men. We focused our analysis on scientific publications recorded in PubMed (the most comprehensive database of life science articles) that acknowledged financial support by the National Institutes of Health (to consider articles of similar quality).

Surprisingly, we found that women had a 10-15% higher likelihood than men of earning first authorships, on average, across more than 100,000 articles published between 1985 and 2009. In fact, women have been achieving first authorships at higher rates than men since the mid 1990s. However, women have remained substantially underrepresented in the last author position during the same time frame. First authorships have not been translating into last authorships for women, which suggests they have been faltering to transition from junior to senior scientist.

One potential reason for this disconnect is that while women in our sample performed better in earning first authorships, on average, they were about 11% less likely to publish in journals with the highest impact, such as Science and the New England Journal of Medicine. It’s not clear why we see this difference, but it could place women at a real disadvantage if hiring and promotion committees focus on publications in the most visible journals.

We conducted a second study that followed the careers of more than 6,000 life scientists who received funding from the National Institutes of Health (NIH), the largest funder of the life sciences. Because scientists depend on federal grants to fund their work, and the government reports these grants, we were able to use this data to determine who entered and progressed in the profession.

Our sample comprised of early-career scientists who received a postdoc grant from the NIH between 1985 and 2009. We followed their subsequent careers (e.g., analyzing publications and grants) to see how many went on to receive an R01 grant, which marks the transition from junior scientist to principal investigator. Being awarded an R01 grant has essentially become a precursor for a faculty career at a research-oriented university. We analyzed how the odds of obtaining one’s first R01 grant varies with gender and with differences in publication records.

Overall, we found that about 1,000 of these individuals transitioned to an R01 grant, but the share of women to do so was 20% lower compared to men. And the women who did get R01 funding typically required more time to accomplish the transition from postdoc to principal investigator. (We accounted for postdocs who did not pursue R01 funding, which would include, for example, those who left academia.)

About two-thirds of this gender gap appeared due to differences in publication records, such as women publishing less frequently than men and receiving somewhat fewer citations on their papers. The rest of the gap, though, appeared to result from women systematically receiving less credit for their work. For example, while doubling the number of citations per paper reduced the transition time from postdoc grant to R01 by about 20% for men, the same increase in citations per paper only reduced the time to R01 by roughly 13% for women. Even after controlling for a large number of other attributes, such as the journals they published in and whether they specialized in particular areas, a woman will take about one year longer to receive an R01 grant than a man with the same number of citations.

Our findings from these two studies show that women face real barriers to advancing in the life sciences. While they’re entering the field in similar numbers as men, they’re less likely to transition to important R01 funding and prestigious last authorships—both of which matter for achieving a senior scientist position.

While we examined how differences in publication may contribute to the gender gap in early career transitions, we could not determine why these differences exist. Our future work seeks to look at how women’s access to mentors and other organizational resources compares to men’s, as this could influence their research topics and ability to publish in important journals. Of course, other factors may contribute to gender differences in scientists’ career development. But to achieve equal representation among senior scientists, women first have to be able to advance during the earliest phases of their careers.