Perinatal mortality: changes in the diagnostic panorama 1974-1980.

During the period 1974-1980, all late abortions (greater than 19 completed gestational weeks) (LA), late fetal deaths (LFD) and early neonatal deaths (END) were surveyed in a continuous material of 17813 births with an ascertained gestational age established by early ultrasound fetometry. There was no maternal death during the period. The total perinatal mortality (PM) was 0.98% with an END rate of 0.51%. In about 45% of LFD no diagnosis was found. Intrapartum death was extremely rare as was END caused by asphyxia or infection. In END, death from immaturity constituted the major group in the beginning of the period, while after 1977 lethal malformations was the dominating diagnosis. There was a continuous decrease in Idiopathic Respiratory Distress Syndrome (IRDS) as a cause of END. The proportion of END in extremely premature children showed a constant decrease in the beginning of the period. No difference in sex was found in END except for lethal malformations where there was a significant male preponderance. As a consequence of a more active obstetrical care, some fetuses who would previously have been classified as LA were probably delivered liveborn, extremely premature and appeared as END. The question of where to set the limits for what should be included in PM is thus highly relevant.