Few studies examined maternal attachment in childbirth-related postpartum posttraumatic stress disorder (PP-PTSD). We studied 685 postpartum women, assessing for PP-PTSD, non-childbirth PTSD, maternal attachment, pre-birth, birth, and post-birth factors. Attachment was lower in PP-PTSD than in non-childbirth PTSD and no PP-PTSD. Hierarchical regression showed that PP-PTSD predicted less maternal attachment above and beyond pre-birth psychiatric conditions, acute distress in birth, and lack of breastfeeding. Childbirth-induced posttraumatic stress may interfere with the formation of maternal attachment, warranting screening of at-risk women.