Knowledge and reproduction were tied together in the beginning of the Chinese women's movement as a remedial prescription to save the nation. This chapter focuses on women's contestation and negotiation for their own freedom and the right to control their bodies in conjunction with the eugenics movement. Departing from scholarly emphasis on women's participation in the war activities, it begins with a converging moment in the transnational coalition of women's movements and their ensuing separate developments with local agendas. The chapter also focuses on biographical analysis of these female scientists at the intersection of the birth-control movement and the eugenics movement. The visit of Margaret Sanger to Japan and China, and the ensuing social movement of birth-control campaigns, stirred up issues such as population control, women's rights, the prevention of sexually transmitted diseases (STD), and the scientific knowledge of contraception. The chapter concludes with their different definitions of morality and their strategy of reproduction in contrast with the conventional approaches.