AbstractPregnant research participants have long been excluded from early-stage clinical trials. This stance has been considered ethically justifiable because it upholds the principle of nonmaleficence by avoiding potential harm, using the fetus(es) as the point of reference. However, there are unintended consequences with this default approach. To illustrate these consequences, this article will review the inclusion and exclusion criteria of the Phase II and Phase III SARS-CoV-2 vaccine trials, demonstrating a downstream delay of vaccine recommendations, which hindered public health efforts. Incorporating ethical principles in addition to nonmaleficence, the authors propose an intentional effort to include pregnant participants in Phase II and Phase III designs. We consider the goals of Phase II and Phase III research of demonstrating safety and efficacy and propose that pregnant participants can potentially support these goals. Rather than reflexive exclusion, the gestational age of the participant or the pharmacology of the trial intervention may be considered as part of inclusion for pregnant participants. Expanding the principles beyond nonmaleficence, pregnancy may become a demographic variable rather than an exclusion criterion.