<p>This article interrogates the diagnostic category of gestational diabetes mellitus (GDM) as a spectral illness, that is transitory, affectively charged, and shaped by regimes of anticipation and surveillance. Drawing on six months of ethnographic fieldwork in Vancouver hospitals, I trace how GDM is enacted not through embodied symptoms but through numerical thresholds, creating a clinical reality that arrives unannounced and often departs before it is ever felt. Despite its apparent disappearance, GDM leaves behind lingering traces: haunting fears of the return of chronic illness, maternal guilt, residual disordered eating tendencies, and the specter of intergenerational risk. Through a conceptual framework that brings together Derrida’s notions of the hauntology, spectres, ghosts, and revenants; Fischer’s temporal disjunctions of the “no longer” and the “not yet”; and other theories of ‘at-riskness’ and surveillance in medicine, I argue that GDM initiates a haunting that reconfigures the experience of pregnancy. It summons past traumas, elicits future-oriented anxieties, and embeds the maternal body within a terrain of ongoing clinical and moral oversight. As a diagnosis with a temporal expiration but lasting affective and embodied consequences, GDM demands new analytic attention to how biomedicine produces and manages uncertainty, anticipation, spectrality, and haunting.</p>