From the Guidelines

The U.S. government required federally funded studies to include women through the NIH Revitalization Act of 1993.

This act mandated that all NIH-supported human-subject research include women and members of minority populations and subpopulations 1.
The act required the NIH to regularly report aggregate data on the inclusion of women and minorities across human-subject research 1.
The policy change has had a positive impact on increasing the participation of women in research, with a median of 46% of participants being women in 2015, up from 38% in 2009 and 43% in 2004 1.
However, the inclusion of minority populations in clinical research remains low, with only 13.4% of NIH-sponsored published research studies in 2015 including analysis by race or ethnicity 1.
The 21st Century Cures Act of 2016 updated the NIH policy to require valid analyses by sex/gender and race/ethnicity in the results reported in clinicaltrials.gov for NIH-defined phase III clinical trials 1.

The NIH has implemented various strategies to enforce this policy, including scoring or raising the importance of the Inclusion of Women and Minorities section of the NIH grant application, investing in resources to support recruitment of minority populations, and revising criteria in funding announcements to emphasize the inclusion of racial/ethnic minorities 1.
The NIH has also engaged in efforts to address deficiencies in the recruitment and retention of minorities in clinical research, including providing training to scientific review officers to recognize bias in the study section and increasing the availability of loan repayment programs or other policies 1.

From the Research

The U.S. government required federally funded studies to include women through policies implemented by the National Institutes of Health (NIH) and the Food and Drug Administration (FDA) 2.
The NIH revised its policies in 1999 to require the inclusion of women and minorities in clinical trials, as well as an analysis of gender and racial differences 2.
The FDA also revised its policy in 1999 to include women and men in clinical trials if both would receive the drug when marketed, and to expect a gender analysis to be performed 2.
The FDA lifted its 1977 ban on including women of childbearing potential in the early phases of drug studies in 1999 2.

An analysis of cardiovascular clinical trials funded by the National Heart, Lung, and Blood Institute between 1965 and 1998 found that the overall enrollment rate for women exceeded the prevalence of cardiovascular disease in women in the general population 3.
The enrollment rate for women increased over time, but women were under-enrolled in studies of heart failure 3.
Federal efforts to increase the representation of women in clinical trials have been moderately successful, primarily due to the institution of a small number of large, single-sex trials involving coronary artery disease 3.

An analysis of funding by the U.S. National Institutes of Health found that in nearly three-quarters of the cases where a disease afflicts primarily one gender, the funding pattern favors males 4.
The disparity between actual funding and that which is commensurate with burden is nearly twice as large for diseases that favor males versus those that favor females 4.

A study of NIH-funded randomized controlled trials published in 2021 found that analysis and reporting by sex, race, and ethnicity significantly increased from previous waves 5.
The median proportion of female participants in these trials was 43%, and 43% of trials reported an outcome by sex, included sex as a covariate in statistical analysis, or reported results by sex 5.