Background: The experience of a neonate hospitalized in the NICU is an understandably traumatic experience for parents, especially for the mothers of neonates. This mental distress resulting from preterm birth and/or NICU hospitalization can be understood as post-traumatic symptomatology, according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5 version). The aim of this study is to investigate the impact of the admission of a neonate to the NICU (forany reason) on the development of postpartum PTSD in a sample of women after cesarean section.Methods: A total of 469 women who gave birth with cesarean section from July 2019 to June 2020 participated in this study out of the original sample of 490 women who consented to participate. Data were obtained from the researcher’s socio-demographic questionnaire and the post-traumatic stress checklist (PCL-5) from the Diagnostic and Statistical Manual of Mental Disorders DCM-5 version. Results: In total,11.7% of the sample experienced postpartum PTSD. There is a strong relationship between the inclusion of a neonate to the NICU due to perinatal stress, breathing difficulties, infections, and IUGR with postpartum PTSD (37.7%) in relation to the perinatal stress Criterion A (fear for the life of the neonate), the first criterion of postpartum PTSD. Conclusions: Additional measures must be taken for mothers of children who have been admitted to the neonatal intensive care unit with psychological support interventions and a reassessment of their mental state.