A 10-year follow-up study of sex inclusion in the biological sciences

TLDR

The NIH’s 2016 policy to incorporate sex as a biological variable was introduced to counter the long‑standing male bias in biomedical research. The study sought to assess the impact of this policy by conducting a bibliometric analysis of 34 journals across nine biological disciplines in 2019 and comparing the results to a 2009 study by Beery and Zucker. The authors performed a bibliometric review of 2019 publications in the selected journals, evaluating sex inclusion and the presence of sex‑specific analyses, and benchmarked these findings against the earlier 2009 dataset. The analysis showed a significant increase in studies reporting both sexes across all disciplines, yet eight disciplines did not improve in sex‑specific data analysis; most studies failed to justify single‑sex designs or sex‑based analyses, often citing misconceptions about female hormonal variability, highlighting persistent gaps in sex‑inclusive research practices.

Abstract

In 2016, to address the historical overrepresentation of male subjects in biomedical research, the US National Institutes of Health implemented a policy requiring investigators to consider sex as a biological variable. In order to assess the impact of this policy, we conducted a bibliometric analysis across nine biological disciplines for papers published in 34 journals in 2019, and compared our results with those of a similar study carried out by Beery and Zucker in 2009. There was a significant increase in the proportion of studies that included both sexes across all nine disciplines, but in eight of the disciplines there was no change in the proportion studies that included data analyzed by sex. The majority of studies failed to provide rationale for single-sex studies or the lack of sex-based analyses, and those that did relied on misconceptions surrounding the hormonal variability of females. Together, these data demonstrate that while sex-inclusive research practices are more commonplace, there are still gaps in analyses and reporting of data by sex in many biological disciplines.