"Why is my body malfunctioning?": Legitimacy narratives of women experiencing chronic lactation insufficiency

Despite medical and public health emphasis on breastfeeding, individuals with chronic lactation insufficiency (CLI), which is persistent low milk supply that does not resolve despite adherence to recommended lactation practices, often face clinical dismissal, diagnostic ambiguity, and shame. Drawing on narrative theory and legitimacy narratives, this study examines how women construct and negotiate the legitimacy of their CLI experiences across clinical, cultural, and experiential domains. We conducted in-depth semi-structured interviews with 30 women who self-identified as having experienced CLI, analyzing data using phronetic iterative analysis. Findings reveal that participants engaged in the four forms of legitimacy work: legitimizing suffering, asserting moral legitimacy through effort, seeking medical legitimacy, and pursuing public legitimacy. We extend legitimacy narrative theory through a proposed Triple Bind Framework, and argue that CLI narratives are structurally produced at the intersection of three dominant and mutually reinforcing master narratives: biomedical ("just use formula"), feminist ("trust your body"), and neoliberal ("try harder"). When all three fail to account for the physiological reality of CLI, women construct legitimacy narratives as epistemic resistance. These findings carry implications for patient-provider communication, calling for narrative humility, recognition of physiological risk factors, and dedicated support spaces for individuals with CLI. We argue that a biosocial perspective, one that honors embodied variation and invites women to co-create breastfeeding knowledge, is essential to improving maternal and infant health outcomes.