Each year, millions of pregnant women are confronted with serious medical illnesses. Yet the evidence base for treating them is distressingly poor. Due in part to ethical concerns about conducting research with pregnant women, researchers and institutional review boards continue to regard pregnancy as a nearautomatic cause of exclusion, even in studies carrying no additional risk to the fetus. As a consequence, pregnant women and their doctors are often forced to make difficult, anxiety-filled decisions about whether to use or continue a medication in pregnancy, guessing about what medications to use, what doses to prescribe or take, or whether to use medications at all. In this article, we outline four reasons why we must confront the challenges of including pregnant women in medical research: the need for effective treatment for women during pregnancy, considerations of fetal safety, the harm from reticence to prescribe needed medication, and the broader issues of justice and access to the benefits of research participation. We then outline three steps that legislators, regulators, and health advocates should take to advance the responsible inclusion of pregnant women in research critical to evidence-based therapeutics during pregnancy. A few small changes can make an immediate and significant difference.