Rigorous clinical trials are designed to ensure that study participants reflect individuals who may ultimately benefit from the treatment or intervention. Underrepresentation in trials leads to “data-free zones” in the safety and efficacy evidence base for commonly used and novel medications. This evidence gap leads to decisional uncertainty for patients, physicians and other clinicians, and regulatory bodies. Guidance from the National Institute of Allergy and Infectious Diseases from 2017 appropriately called for evidence from preclinical animal studies of reproductive toxicity to inform study eligibility requirements such as contraception.1,2