The aim of this study was to investigate the association of postpartum post-traumatic stress disorder (PP-PTSD) symptoms and subjective rates of traumatic birth experience with past traumatic life events (physical and sexual assault, child abuse, perinatal loss, previous traumatic birth experience, and the cumulative traumatic experience). A sample of Russian women (n = 2579) who gave birth within the previous 12 months, filled in a web-based survey, where they reported demographic and obstetric characteristics and past traumatic experiences, evaluated their birth experience (0 = not traumatic, 10 = extremely traumatic), and completed the City Birth Trauma Scale (CBiTS). We found that PP-PTSD symptoms were higher among women who previously experienced physical (F = 22.02, p < 0.001) and sexual (F = 15.98, p < 0.001) assault and child abuse (F = 69.25, p < 0.001), with only associations with child abuse (F = 21.14, p < 0.001) remaining significant for subjective rates of traumatic birth experience. Perinatal loss and previous traumatic birth showed moderate but inconsistent effects. Support during labor did not have a buffering effect for participants with past traumatic experiences but showed a universally protective effect against PP-PTSD. Trauma-informed practices and allowing women to have a supportive birth team of choice during childbirth are promising avenues to minimize the incidence of PP-PTSD and improve the childbirth experience for all women.