The occurrence of interpersonal trauma is a reality for many women, with effects that often persist long after the traumatic events end. The purpose of this feminist grounded theory study was to examine how past trauma shaped the lives of women as they became new mothers. We recruited a purposive sample of 32 women from two Canadian communities and conducted semistructured, dialogic interviews during the second trimester of pregnancy. We analyzed data using thematic content analytic methods, including open coding whereby we read transcripts line by line and applied codes to portions of text that illustrated concepts or themes. The substantive grounded theory, "laboring to mother in the context of past trauma," describes the exceedingly difficult emotional and cognitive work undertaken by pregnant women with histories of trauma as they anticipate becoming mothers. In this article, we present key components of the theory and offer recommendations for health and social service providers.