Over the last year, there have been numerous studies which enhanced our understanding of women’s health and well-being. Yet, perhaps the most significant advancement of women’s health in 2016 comes not from the results of a clinical trial or a scientific study, but from a policy implemented by the National Institutes of Health (NIH) which requires federally funded investigators to, “consider sex as a biological variable.” Yet, what does it actually mean to consider sex as a biological variable, and how will it impact women going forward?

   We know that men and women experience many diseases and disorders differently. Sex differences can be found in the symptoms, severity, prevalence, and age at onset for a variety of conditions. However, a majority of biomedical research is conducted with a preferential bias towards the male sex. Investigators tend to use male cells or animals, neglect to report which sexes were studied, or fail to mention if any sex-differences were identified [1-3]. These practices limit our understanding of how sex impacts health and disease and hinder the development of therapeutics. Thus, the new NIH policy asks investigators to conduct their research in both males and females or provide strong justification as to why studying one sex would be more appropriate.

    As we enter the era of personalized medicine, the need for sex-based science becomes even more apparent. In order to treat patients based on individual genes, we need to consider their chromosomes, including XX or XY. By requiring scientists and clinicians to consider sex as a biological variable, women’s health is made a priority from the bench to the bedside.