Immunization is one of the most effective ways to prevent infectious diseases. However, vaccination rates are suboptimal in the United States. Obstetric providers are critical in influencing vaccine decision making among pregnant women, as trust between a patient and provider may facilitate willingness to accept vaccination. Little is known about how power between a patient and provider affects vaccine acceptance. This study explored pregnant women's trust in obstetric providers within the context of vaccines. Using concepts from the relational theory of power, we conducted 40 in-depth interviews with a purposive sample of pregnant women from four Ob-Gyn practices each in Georgia and Colorado. Results suggest that to enhance trust, providers could gain distributive power by conveying empathy. Designated power through medical experience was associated with both trust and distrust, as some women trusted their providers because of their authority and medical credentials, while others viewed authority and experience as reasons to distrust their provider. To increase acceptance, providers should acknowledge the underlying power dynamics within these interpersonal relationships and strengthen rapport with patients through empathy and dialogue.