Histologic, infectious, and molecular correlates of idiopathic spontaneous abortion and perinatal mortality.

The purpose of this study was to analyze the placental and neonatal tissues in fatal cases for a wide variety of infectious agents and cytokine expression. Placentas and corresponding neonatal tissues in 21 consecutive cases of idiopathic spontaneous abortion or perinatal death, before or within 2 days of birth, were tested for an infectious agent. The controls included 10 consecutive cases of fetal and placental tissues from therapeutic abortions, 5 placentas from unremarkable childbirths, and 11 placentas from cases of spontaneous abortion or perinatal death of known cause (ruptured uterus, placenta abruption, prolapsed cord). An intrauterine infection was noted in 16 of 21 (76%) of the placentas associated with neonatal mortality; in each case, the same infectious agent was found in the neonatal tissues, primarily the spleen. The most common infectious agent was enterovirus/coxsackie virus (10 cases); the histologic findings in the placenta were nonspecific. There was strong expression of TNF-alpha in the placenta and spleen of each of the cases of intrauterine infection and in none of the 26 controls. It is concluded that in utero infection and the associated cytokine up-regulation are responsible for many cases of unexplained fetal and neonatal loss.