This chapter shows, with a view to prenatal diagnosis, that providing scientific information and science-based diagnostics not only results in more rational decisions and a better care, but results in clear-cut boundaries between sick and healthy become blurred, leading to new uncertainties. In order to reflexively deal with non-knowledge and uncertainty, the knowledge and the experiences of the women affected supplement expert knowledge. Decision-making turns out to be a deliberative process, where the voice and the values of patients tend to gain a constitutive role. With respect to the debate on non-knowledge, prenatal diagnosis has some implications to be further reflected upon. It shows that assigning a more active role to patients in decision-making may be a way of constructively dealing with uncertainty and non-knowledge. Many issues regarding innovation, technology and the environment are associated with uncertainty, non-knowledge and long-lasting disagreement.