OBJECTIVES: To describe the development and the methodology for validation of a new scale for postpartum anxiety for mothers of preterm infants, and a 'Velcro' sub-scale of the Postpartum Specific Anxiety Scale for use with mothers who have had infants admitted to the Neonatal Intensive Care Unit. METHODS: We undertook three forms of iterative psychometric development: (1) Patient and public involvement and engagement discussions with key clinical, academic, and lay stakeholders to understand the needs for modifying the Postpartum Specific Anxiety Scale-Research Short Form for use in this population; (2) Expert panel ratings with clinical and academic stakeholders; and (3) Cognitive interviews with mothers to ensure items were relevant, comprehensive, and understandable. Planned studies must ensure the psychometric properties of these two new scales. RESULTS: Patient and Public Involvement and Engagement discussions identified clear avenues for modification of the PSAS-RSF, but the need for an additional NICU-specific scale was clear. Experts rated the new items highly on their relevance. Cognitive interviews further ensured that items were well understood and that meaning was being interpreted in the intended manner. Only minor changes to the scales were implemented after each change. CONCLUSIONS: This is the first study to describe the process of developing and the subsequent proposed validation of postpartum-specific tools for use with mothers of preterm infants and those with infants in the Neonatal Intensive Care Unit. Clear avenues have been identified for the validation and implementation of both measures.