Unexplained antepartum fetal death in Norway, 1985-97: diagnostic validation and some epidemiologic aspects

OBJECTIVE: To validate the diagnosis of an unexplained antepartum fetal death in the Medical Birth Registry of Norway against data obtained from hospital records, alone and combined with autopsy data. To compare epidemiologic characteristics of an unexplained fetal death based on cases recorded by the three data sources. METHODS: Data on unexplained fetal deaths in the Registry were compared with clinical and autopsy data from 108 457 singletons with a gestational age >or= 28 weeks or a birthweight >or= 1000 g delivered in 1985-97 at Haukeland Hospital in Bergen and Aker Hospital in Oslo. RESULTS: Compared with clinical data, the positive and negative predictive values of a Registry diagnosis of an unexplained fetal death were 88% and 86%, respectively, while the sensitivity and specificity were 76% and 93%, respectively. Compared with clinical and autopsy data combined, the positive and negative predictive values of a Registry diagnosis of an unexplained fetal death were 77% and 89%, respectively, while the sensitivity and specificity were 78% and 88%, respectively. High agreement was observed in comparisons between the data sources of risks according to various independent variables. CONCLUSIONS: The validity of a diagnosis of an unexplained antepartum fetal death based on the Medical Birth Registry of Norway is sufficiently high to justify future large-scale epidemiologic studies based on this database.