History of gender bias and exclusion in clinical trials

Women only make up about 41% of clinical trial participants, despite being more than half of the world’s population.

Did you know that it was not until 1993 that the inclusion of females in clinical trials was required by law? Females were deemed “too complex” for trials. This was based on biological makeup, including hormonal changes and the potential risks in childbearing. It’s hard to believe, but small males were used to determine if many of the treatments we use today would be safe for females. 

The LGBTQ+ community has also been left out. Some trials exclude medications used for gender-affirming care. Many trial teams are not trained to ask key questions, and facilities at trial sites are often outdated. These and other barriers keep too many of us from joining trials. 

Timeline of gender and clinical trials

Modern gynecology has its roots in cruel experiments done on enslaved Black females. Dr. James Sims is referred to as the father of gynecology. He developed tools and techniques that advanced female reproductive health. But his work came at the expense of enslaved Black females. 

1860 

Pre-American Civil War 

painting portraying Sims gynecological experiments on Black women
In 1919, the Institute for Sexual Science was established in Germany. The institute was the world’s first clinic of its kind. It soon became a hub for research on gender-affirming care. 

1919

Early 20th century 

b/w antique photo of group of friends sitting together informally
Danish painter, Lili Elbe, was assigned male at birth. Elbe realized her true gender identity late in life. She then had the world’s first known gender-affirming surgery. She had five surgeries starting in 1930. These were highly experimental procedures at the time. 

1930

Experimental sex reassignment 

b/w antique photo of Lili Elbe holding a fan
Biologist Gregory Pincus and Dr. John Rock conducted illegal, secret research that led to the first birth control pill. They aimed to find out if a hormone produced during pregnancy could prevent pregnancy in females. They disguised their work as a “fertility trial.” They later moved this unethical trial to Puerto Rico to evade scrutiny. They recruited poor women to be in the trial. The women were not told they were taking part in a trial. And they were not aware of the risks to their health and their lives. 

1950s

Progesterone, birth control studies 

b/w photo of women in a contraceptives demonstration
Thalidomide, intended to help with sleep and nausea, was a widely used drug in Canada and Europe in the 1950s until it was taken off the market in 1961. During this time, it was given to over 1,000 doctors to give to their pregnant patients as samples in the US, though it was never authorized by the FDA. Thousands of people in many countries who took this drug while pregnant gave birth to babies with deformed limbs, and unfortunately many of them did not survive past birth. This medical disaster led the FDA to require guidelines on ensuring drug safety. 

1962 

Thalidomide tragedy 

b/w photo of children with thalidomide induced disabilities writing in books
After the thalidomide tragedy, the FDA created a policy excluding females of childbearing age from phase one and phase two clinical trials. However, this also excluded females who took steps to avoid pregnancy, limiting participation of females overall. 

1977

Exclusion of females in clinical trials 

The NIH Revitalization Act of 1993 changed the course of clinical trials. This law required trials funded by the U.S. government to include females. Other trial sponsors followed suit. Since then, the number of females in trials has gone up each year. 

1993 

NIH Revitalization Act 

exterior of an NIH research building
Guidelines written in 2009 addressed healthcare needs of transgender patients. They covered diagnosis, treatment, and preventive care. They also addressed potential risks of gender-transition therapies. These guidelines were updated in 2017. 

2009

Caring for transgender patients 

colors of transgender pride flag
As of 2019, the World Health Organization (WHO) does not classify being transgender as a mental health condition. The WHO has affirmed gender identity as part of a person’s sexual health. This key step aims to reduce stigma and improve access to care.

2019 

Transgender redefined

Flag of the WHO flying
As clinical trials evolve, innovative approaches move us forward. Female and LGBTQ+ voices are being heard. Researchers are working to address their needs in trial designs. 

Clinical trials today

group of doctors talking

Females in clinical trials

Females make up 51% of the U.S. population. But they make up only 41% of clinical trial participants. Over the past three decades, the gap has narrowed. But it’s still too large. 

The only way to know how a potential treatment or vaccine might work in females is to test it in females. That’s why we need to increase female participation in trials. Ways we might reach this goal include: 

  • Travel support for trial visits 
  • Flexible trial visit schedules 
  • More women on trial teams 
  • Support for childcare needs during trial visits 

Building trust in clinical trials

To build trust, trial sponsors and teams can engage with a wide variety of communities and understand their concerns. They can address social health factors and offer educational resources that help all of us understand trials. We’re headed in the right direction, but there’s a long way to go.

smiling woman

Clinical trials for health conditions that affect females more than males

The participation gap in clinical trials has caused a gap in healthcare. In many cases, we don’t know as much about how potential treatments and vaccines will work in females. This can pose health risks. And the risks can be magnified for health conditions that affect females at a higher rate. 

Illness can affect females in different ways. For example, females have a higher rate of death after a heart attack. Other health conditions that affect females more frequently include: 

  • Breast cancer 
  • Depression 
  • Lung cancer 
  • Menopause 
  • Urinary tract illnesses 

More focus is needed on gender identity

We all deserve the right to live our healthiest lives. And it starts with inclusive clinical trials. Though the numbers vary by study, about 9 percent of adults in the US identify as LGBTQ+, and millions identify as transgender and/or nonbinary. 

Bias faced by people in these groups can lead to medical mistrust. They may think trials are not for them. But that does not mean they should be left out. According to one report, less than 1% of clinical trials in the United States include people who identify as nonbinary or transgender—but this group represents about 1% of the population. 

Sponsors have worked to improve trial access for all. But efforts have focused largely on race and ethnicity. Trial sponsors should take additional steps to include the LGBTQ+ community. For example, sponsors can: 

  • Consider negative experiences the LGBTQ+ community has faced and work on building trust 
  • Ask participants about their gender identity 
  • Find more trial sites that have inclusive facilities 
  • Include gender-neutral language and images in trial-related materials 
  • Train trial teams to be sensitive and inclusive (including asking about and using a person’s pronouns) 
  • Engage advocacy groups for input on trial design   
  • Recognize and remove barriers to study participation 
smiling nonbinary person of color

Facts and fiction: a look at misconceptions

When it comes to clinical trials, it’s important to separate fact from fiction. This can help you make a more informed choice about participating. Let’s start by clearing up two misconceptions about clinical trial gender bias today.

Bias and Exclusion

FICTION: LGBTQ+ people are not allowed to join clinical trials.

FACT: Most trials don’t exclude people based on gender identity or sexual orientation. All trials have criteria for who can be in them. But an Institutional Review Board (IRB) reviews the criteria. The IRB makes sure you won’t be kept out of a trial unless there is a reason based on science.

Trial Participants

FICTION: Most clinical trials are for male participants only.

FACT: In the past, clinical trial participants were almost all white males. But that changed dramatically in the early 1990s. The NIH Revitalization Act of 1993 requires that females be included in trials funded by the U.S. government. Other trial sponsors adopted this new approach. Trial teams now look for people who match all patients who may benefit from a potential treatment or vaccine in the future. For most trials, this means they are looking for females and males in equal numbers. A recent study found that 41 percent of trial participants are female.

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