This study was carried out to determine the effects of posttraumatic stress disorder (PTSD) on maternal adaptation and newborn perception in postpartum primiparous mothers. The research was designed as descriptive and cross-sectional. A total of 378 mothers who were in postpartum 6-8 weeks were reached. Of the 378 mothers participating in the study, 97 (25.7%) scored above the posttraumatic stress scale cut-off point (≥ 33). After vaginal childbirth, primiparous mothers with PTSD in the postpartum period were found to have weaker maternal adaptation and newborn perception than mothers without (p < 0.001). It was determined that primiparous mothers with PTSD who have experienced traumatic birth have difficulty in adapting to motherhood and have problems in perceiving, accepting, and bonding with the newborn. Mothers in the postpartum period should be screened for PTS symptoms by home visits by health professionals to ensure that mothers receive the necessary psychological support and care.