Hypothesis/aims of study. In the past 15 years, statistical reports have standardly identified five main causes of perinatal loss: Hypoxia/asphyxia and its consequences, congenital malformations, respiratory disorders, intrauterine infections, and birth injuries. The cause of perinatal loss is indicated in 17-83% of cases, but this percentage can be increased by a careful analysis of the course of pregnancy, childbirth, and the results of autopsy. The aim of this study was to analyze the frequency of verification of the causes of perinatal death in St. Petersburg and the Leningrad Region for 2006-2018. Study design, materials and methods. The methodology of determining the cause of perinatal loss in St. Petersburg and the Leningrad Region for 2006-2018 was analyzed according to the reports of the St. Petersburg State Budgetary Healthcare Institution Medical Information and Analytical Center) and the Leningrad Regional State Budgetary Healthcare Institution Medical Information Analytical Center, as well as the Leningrad Regional Pathological and Anatomical Bureau. Further, the frequency of cases in which the cause of perinatal loss was not indicated was estimated in dynamics over the analyzed period. Results. The methodology and problems arising in establishing the basic diagnoses were studied: Intrauterine hypoxia (P20.0), asphyxia during childbirth (P21), respiratory disorders in the newborn that occurred in the perinatal period (P22-P28), and hemorrhagic and hematological disorders in the fetus and newborn (P50-P61). Differences in the frequency of diagnosis of causes of death in Leningrad Regional Pathological and Anatomical Bureau are explained. Those are due to the methodology for establishing a diagnosis of chronic placental insufficiency (O43.8, other placental disorders: Dysfunction, heart attack) based on the detection of hypoxic cardiopathy at autopsy, and due to the approach developed by the institution to detect intrauterine infections. The frequency of cases in which the cause of perinatal loss was not indicated was estimated, the reasons and possibilities of this being explained. Conclusion. Low information content of the official statistical reports makes it difficult to analyze the real causes of perinatal loss.