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What Do We Mean by Sex and Gender?

Women’s Health Research at Yale is committed to advancing the health of a diverse society. Our focus is studying the health of women and the role of sex and gender in health outcomes. In this effort, it is important to use language that captures the different concepts of sex and gender so that our science and our findings can be more precise and better serve everyone.

What do we mean by sex and gender? Aren’t these terms interchangeable? Perhaps at some point in time they were used as synonyms, but this is no longer true in science.

In 2001, a committee convened by the Institute of Medicine (IOM), a nonprofit think tank that took on issues of importance to the national health, addressed the question of – Beyond reproductive health, is it important to study the biology of women in addition to the biology of men?

The IOM, now embedded within the National Academies of Science, Engineering, and Medicine, concluded that, beyond reproductive health, there were major differences in the biology of women and men affecting health and influencing treatment and prevention strategies – making it essential to study the biology of both women and men.
The committee also emphasized that health is not determined solely by biology. Rather, health is influenced by biology and by sociocultural and psychological experience. To differentiate between these broad areas of investigation, the committee created working definitions of “sex” — when referring to biology — and “gender” — when referring to self-representation influenced by social, cultural, and personal experience. They advised that:

  • the term sex be used as a biological classification, generally as male or female, according to the reproductive organs and functions that derive from the chromosomal complement [generally XX for female and XY for male].
  • the term gender be used to refer to a person's self-representation influenced by social, cultural, and personal experience.

These “working definitions” were a good start in recognizing the value of studying both biological and social determinants of health and their interactions. Yet, they were always meant to evolve as we learn more about ourselves. For example, the original concepts of sex and gender were implemented as binary notions (female, male; woman, man). However, we now understand that biological sex can be ambiguous and is not always binary, and gender can be expressed in many ways including non-binary or genderqueer identities. With this new understanding, we must continue to adapt our terminology ensuring that it is inclusive, respectful, and more accurate.

Let's See Equality Differently

Women and men deserve equal treatment under the law and equal opportunities to succeed in life. And yet that doesn’t mean we are all the same. Because when it comes to medical research and health care, men and women are not identical. And that can make a difference in how we detect and treat diseases and conditions that may affect men and women differently.