With a national rate of 82.4%, France is currently one of the world’s leading users of epidural analgesia (EA), which is promoted not just as a pain reliever but also as a technology that makes childbirth safer. Drawing on analytical tools from science and technology studies, reproductive studies and ignorance studies, I will show how this obstetric drug came to be widely used after significant knowledge/ignorance battles had been fought during heated public and medical controversy in the 1970s. Different visions of the ‘knowns’, the ‘unknowns’ and ‘know-how’ came into conflict in this context, supported by a series of moral, political and feminist justifications that were often at odds with one another. While the defenders of natural birth clashed with feminists, created ambiguities around conceptions of the maternal body, and struggled to produce large-scale clinical knowledge on the risks of EA, the defenders of EA put forward technological promises and biomedical modernization as a means to outstrip the knowledge wars. In the aftermath of this epistemic battle, EA was to gradually become an ‘unlearner’ technology; that is, a modern tool that radically silenced the maternal body and led to denial, disregard or unawareness of a whole range of shared and alternative knowledges and ‘know-how’ relating to female physiology and the birth process that are free of pharmaceutical products and medical interventions.