Background <p>Among persons of childbearing age, advanced chronic kidney disease (stage 3–5) reportedly affects approximately 1 in 150 individuals. Birth rates compared to the general population are lower in kidney transplant recipients and in individuals undergoing dialysis, estimated at approximately 1:10 and 1:100, respectively. Despite these challenges, the incidence of pregnancy among those with chronic kidney disease is increasing, and birthing parents with advanced chronic kidney disease, including those undergoing dialysis or with a kidney transplantation, express a strong desire to breastfeed prenatally and initiate breastfeeding after childbirth. However, the factors influencing breastfeeding outcomes and their milk composition in birthing parents with kidney disease are not well understood. At present, no clinical practice guidelines exist to specifically address lactation management for birthing parents with kidney disease, leaving a gap in support and care for this population.</p> Aims <p>Our primary aims are to describe lactation outcomes and define milk composition for birthing parents with advanced chronic kidney disease, post-kidney transplantation, or receiving dialysis therapy. Our secondary aims are to describe the breastfeeding experience, including attitudes, self-efficacy, and challenges, and evaluate infant health outcomes including developmental and medical history.</p> Methods <p>We are conducting a prospective observational cohort study in California, using mixed methods to examine lactation outcomes, breastfeeding experience, parent-infant health, and milk composition among participants (<i>N</i> ≈ 10) with chronic kidney disease, kidney transplantation or dialysis. Participants will complete surveys, oral interviews, breastfeeding telemedicine consultations, 24-hour infant test-weighing, and milk sample collection. Control participants without kidney disease and with either normal (600–1035 mL) or low (&lt; 600 mL) milk supply will be recruited. Milk composition (macronutrients, metabolome, electrolytes, cytokines, and immunoglobulins) will be compared. We will use descriptive statistics to summarize participant characteristics, and inductive thematic analysis to generate contextual insight into lactation patterns and birthing parent experiences.</p> Discussion <p>Outcomes of this study will guide practice recommendations for the multidisciplinary care team supporting birthing parents with advanced chronic kidney disease, kidney transplantation or undergoing dialysis, ensuring breastfeeding safety and appropriate support.</p>