Studying Sex Differences in Biomedical Research


Over the past two decades, we have learned a lot about how men and women respond differently to medications. This knowledge came after a concerted effort in the early '90's to increase the number of women in NIH-funded clinical research. Today, just over half of NIH-funded clinical research participants are women. Unfortunately, experimental design in cell and animal research has not always followed suit.  


Over-reliance on male animals and neglect of attention to the sex of cells used in research can lead to oversight of key sex-related differences. These differences should guide clinical studies, and ultimately, clinical practice. In 2014, the NIH began instituting a new policy that requires applicants to report their plans for the balance of male and female cells and animals in preclinical studies in all future grant applications, unless sex-specific inclusion is unwarranted. A commentary published in Nature by NIH Director Francis Collins, M.D., PH.D, and Director for Research on Women's Health Janine A. Clayton, M.D., called on scientists to take a deliberate approach in considering sex in preclinical research to make sure that men and women get the full benefit from medical research. This approach will result in greater awareness of the need to study both sexes, demonstrate how research can incorporate sex, and reinforce the value of taking it into account as these studies yield results.


SABV graphic

As part of a larger NIH initiative coordinated by the Office of Research on Women’s Health (ORWH), the NIH Common Fund recognized an opportunity to provide insights into sex differences. Many programs supported by the Common Fund built large data repositories, each containing varied biomedical information on both male and female participants. These large data sets were ripe for exploration of meaningful sex differences, and the Common Fund provided funding supplements to a number of researchers to consider sex as a biological variable (SABV) in their Common Fund-supported research. Information on these supplements can be found below.


In an effort to promote the importance of studying sex as a biological variable, ORWH and the Common Fund hosted a joint workshop in October, 2017. Not only did this workshop highlight important sex differences in biomedical research, it also provided useful information to scientists about developing new research strategies to include SABV and how to communicate with their colleagues about the importance of including SABV in research design. Find more information on the SABV workshop.


Supplemental Award Information





Information from the NIH Office of Research on Women's Health (ORWH)

This page last reviewed on March 7, 2018