The aim of our study was to categorize fetal deaths by different diagnostic groups and see to what extent an autopsy of a presumably normal fetus contributes to the final diagnosis and how many unexplained fetal deaths remain unexplained after examination of the placenta. We reviewed autopsy reports of 351 fetuses with a gestational age of 12 or more weeks at the Department of Pathology and Medical Genetics at St Olavs Hospital during the years 2001 through 2010. In our records, 38.5% (135 of 351) of the deaths were due to noninfectious placenta causes, 31.6% (111 of 351) were caused by infections, and 29.9% (105 of 351) of the fetal deaths remained unexplained after autopsy. We also found that an inconclusive report was more common early in pregnancy. The incidence of fetal loss due to circulatory disturbances in the placenta increased toward term. Infections were evenly distributed in intrauterine fetal deaths, although in spontaneous abortions, they were more frequent during the second trimester. For both explained and unexplained deaths, we observed a bimodal distribution, with peaks in the early second trimester and late third trimester toward term.
Keywords: autopsy; intrauterine fetal death; placenta.