With a $3 billion investment by the federal government, the National Children's Study (NCS) recently began recruitment. The NCS is a golden-and potentially missed-opportunity to study one of the most underrepresented populations in clinical research: pregnant women. As the nation's largest-ever study of children's health, the NCS will examine the effects of the environment on children from before birth to 21 years of age, with participants sampled primarily through women during pregnancy. Thus the NCS presents a rare opportunity to study the health of women during and after pregnancy, in addition to the health of their children. On both moral and policy grounds, we make the case for inclusion of women's health outcomes in the NCS.