The new paradox of women's health research.

Women have long been underrepresented in biomedical research, prompting efforts to make research more sex inclusive. These advances are essential, but they can create an unintended tension when rigorous inclusion is interpreted as requiring extensive hormonal or reproductive characterization, even when such detail is unnecessary for the question being asked. We examine this paradox, in which standards intended to strengthen research on women may inadvertently make some studies involving females harder to pursue. We argue that characterization should match the claim a study is designed to support, and that funders, institutions and journals must provide the resources needed to make such rigor feasible. Methodological progress should ultimately broaden, not narrow, the evidence base needed to improve women's health.