Although many suffering from congenital heart defects (CHDs) have seen their conditions become chronic in Denmark today, the risk of complications, deteriorations, and further surgical interventions often lurk in the future. Building on fieldwork in outpatient clinics in Denmark and the homes of families living with CHDs, I explore the role outpatient encounters play in families’ efforts to understand and navigate the prognoses of CHDs by examining how they become routine punctuations and images of uncertainty, and how they play into families’ efforts to prepare for futures where CHDs might develop negatively while also trying to keep such scenarios at bay. I argue that these encounters exemplify, generate, and tentatively curb the particular uncertainties of living with CHDs. Hence, I suggest that they can be thought of as prognostic calibrations—a conceptual oxymoron that encapsulates the anxiety and uncertainty that I show persist around CHD prognoses despite many efforts by families and healthcare staff to establish routine, a sense of security, and certainty.