Background Intrauterine fetal death is an agonizing, often unpredictable event. Autopsies of stillborn fetuses, including placentas, are performed to clarify the cause of death. Autopsy results are not always easily understood by the patients or their healthcare providers. Objective To evaluate placental causes of death in stillbirths based on autopsy and placental findings that are related to maternal underperfusion, fetal underperfusion, or inflammatory etiologies in hierarchical order. Methods Retrospective review of 120 autopsy reports of singleton stillborn fetuses and placentas from 23 to 40 weeks of gestation. Results Among the placental causes of death there were 54(51%) cases with direct cause or major contributor to death in the etiology of maternal vascular supply abnormalities, 28(26%) cases in the etiology of fetal vascular supply abnormalities and 13(12%) in the etiology of inflammatory lesions. Maternal vascular supply abnormalities were more common in preterm stillbirths and fetal vascular supply abnormalities were more common among term stillbirths. In 88% of stillbirths, the direct cause or a major contributor to death was found in the placentas. The incidence of unexplained death was 8%. Conclusions Pathological analysis of the placenta is essential for clarifying causes of stillbirths. Using specific simplified categories for abnormal placental findings may increase the benefits of the autopsy report.