This article focuses on the epistemic strategies employed by ultraconservative movements to oppose women's reproductive rights and the ways in which the women's movement counteracts these efforts. The core argument is that nowadays the opponents of gender equality and sexual democracy are seeking not only political but also epistemic power, producing a new body of gender knowledge. A detailed analysis of the struggles around the 2016 Stop Abortion bill in Poland shows, however, that the women's movement can counteract these challenges by mobilizing not only medical and legal expertise, but also tacit knowledge and affects.