This prospective longitudinal study investigated the prevalence of posttraumatic stress disorder (PTSD) in response to pregnancy loss. About 1,370 women were recruited in the early stages of pregnancy and 113 of them had a subsequent pregnancy loss. One and four months after pregnancy loss, they were assessed for PTSD with the Posttraumatic Symptom Scale. Depression was also assessed. The majority had an early loss, i.e., within 20 weeks. At one month, the prevalence of PTSD was 25%, and the symptom-severity was similar to other traumatized populations. Women with PTSD had increased risk of depression: 34% of PTSD cases and 5% of non-cases reported depression. At four months, 7% met the criteria for PTSD, of which half were chronic. In contrast, rates for depression had not declined. The results indicate that pregnancy loss is potentially traumatic, putting women at risk of developing PTSD. In most cases, the disorder is immediate and persists for several months.