Hypothesis/aims of study. Prevention of the most common causes of perinatal mortality provides an opportunity to reduce perinatal losses. It is customary to distinguish between maternal, fetal and placental factors, dividing them into preventable and unavoidable subfactors. Of all nosologies, intrauterine hypoxia and asphyxia of the newborn, infectious (viral and/or microbial) damage to the placenta and fetus/newborn, and placental insufficiency (acute and chronic) are most important. The aim of this study was to analyze perinatal losses most often diagnosed in Saint Petersburg and the Leningrad Region in order to assess the possibility of developing a set of measures to reduce perinatal mortality. Study design, materials and methods. The analysis of perinatal losses in Saint Petersburg and the Leningrad Region in 2006-2018 is based on the official reports of the Saint Petersburg State Budgetary Healthcare Institution Medical Information and Analytical Center and the Leningrad Regional State Budgetary Healthcare Institution Medical Information and Analytical Center, as well as the reports of the Leningrad Regional Pathological and Anatomical Bureau (LRP&AB). Results. The main causes of perinatal losses in Saint Petersburg and the Leningrad Region for 2006-2018 were: Fetal hypoxia (acute and chronic), intrauterine infections, respiratory distress syndrome (for premature babies), congenital malformations, and chromosomal abnormalities. Throughout the period, intrauterine hypoxia and asphyxia of the newborn (which are the pathology manifestation, not etiology) were indicated as leading diagnoses in the conclusions of perinatal death. Moreover, according to the LRP&AB pathomorphological findings, intrauterine infections were the leading (over 60% of cases) cause of perinatal losses over the years. During the analyzed period in Saint Petersburg and the Leningrad Region, a high frequency of individual states arising in the perinatal period remained unchanged without determination of a specific diagnosis, which significantly complicates our analysis. Conclusion. For an adequate diagnosis of the etiological mechanisms of perinatal losses, it is necessary to improve histological examination of the afterbirth and pathomorphological examination of the fetus/newborn using virological and immunological tests. It is also necessary to change the structure of statistical reports, obliging medical institutions to indicate the exact cause of perinatal death, excluding whenever possible the diagnoses of intrauterine hypoxia and asphyxia in labor that indicate no etiological diagnosis explaining the occurrence of hypoxia/asphyxia.