This mixed-methods pilot study investigated maternal perceived stress specific to infant neonatal intensive care unit (NICU) hospitalization as a moderator of the relationship between traumatic childbirth appraisal and symptoms of posttraumatic stress disorder (PTSD). NICU mothers (N = 77) were recruited via social media 1 to 4 months postpartum for a cross-sectional survey about perinatal experiences. Measures included traumatic childbirth, PTSD Checklist for DSM-5, and Parental Stressor Scale (PSS): NICU. Quantitative results indicated that, only at high levels of stress, women who reported traumatic childbirth (68%) reported significantly higher PTSD symptoms [b = 18.00, standard error = 7.18, t = 2.51, P = .015, 95% confidence interval (3.65, 32.36)]. Qualitative analysis identified additional stressors: maternal emotional well-being, dissatisfaction with care, infant health problems, breastfeeding, and additional characteristics of the NICU environment. Results provide supportive evidence that NICU mothers are at high risk for childbirth-related trauma and PTSD. Perceived stress related to the NICU may be an important intervention target when developing trauma-informed patient care. In addition to the domains captured by the PSS: NICU, maternal emotional well-being, interpersonal relationships with NICU staff, and stress related to breastfeeding are additional areas for improvement in the family-centered NICU.