In collaboration with community research partners, a national cross-sectional online Childbirth Experience Survey of pregnant and postpartum birthing people (CBEX) was conducted in 2016. The antepartum-postpartum survey includes items across 19 domains (including patient expectations, preferences and outcomes), and identified 23 childbirth-specific postpartum patient-reported outcomes (PROs) that were predictors of hospital satisfaction. It is currently being offered in 12 California hospitals to identify hospital-specific opportunities for improvement in care. We analyzed postpartum qualitative survey responses to validate the CBEX domains and to assess for any potential new domains. This was an exploratory analysis of qualitative survey data. Using Atlas.ti, we mapped participant responses to the 19 domains and 23 key childbirth-specific PROs. A total of 547 postpartum surveys were completed between October 30, 2018 and September 7, 2020. Of the completed surveys, 175 patients responded to the question, “Is there anything else you would like to share about your birth experience?” Patients could provide multiple comments. A total of 235 comments were analyzed and mapped to the 19 domains (Table 1). Qualitative responses highlighted issues in several subdomains: 1) interventions in labor: pressure from the care team to be induced comparable to pressure about cesareans; 2) pain management: issues related to epidural effectiveness, timing, dosage and education; 3) empathy and respect: issues related to students and residents; and 4) newborn feeding: rough physical handling of patients by nurses, specifically during lactation consults. Postpartum patient comments were entirely mapped to existing CBEX domains, confirming its content validity. These nuances emphasize the importance of patient input into research development and suggest the need for further refinement of topics to be explored and developed into standardized items. The potential for expanding CBEX subdomains and developing additional standardized items will be explored with community research partners.