title: Causes of perinatal mortality excess in prolonged gestations.
abstract: The study sought to determine what proportion of the perinatal mortality excess associated with prolonged gestations was due to placental insufficiency. Using data from a large prospective study of pregnancy, the perinatal mortality rate was 20.9/1000 births for post-term and 11.7/1000 for term infants. Only a quarter of the perinatal mortality rate excess in the post-term pregnancies was due to disorders related to inadequate uteroplacental perfusion, i.e., abruptio placentae, large placental infarcts and marked placental growth retardation. Twenty-six per cent of the mortality excess was due to congenital malformations, 19% to amniotic fluid infections, 8% to Rh erythroblastosis fetalis and the remaining 22% to a variety of other disorders. The post-term mortality excess due to congenital malformations was in infants who had hypoplastic adrenal glands, a well-known cause of prolonged gestation. The 4205 placentas of the post-term infants did not show any significant increases in those microscopic lesions that are characteristic of uteroplacental under-perfusion.
mesh_terms: D000037:Abruptio Placentae / Q000401:mortality; D000653:Amniotic Fluid; D000013:Congenital Abnormalities / Q000401:mortality; D004899:Erythroblastosis, Fetal / Q000401:mortality; D005260:Female; D005313:Fetal Death / Q000209:etiology*; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D007239:Infections / Q000401:mortality; D010927:Placental Insufficiency / Q000401:mortality; D011247:Pregnancy; D011273:Pregnancy, Prolonged