Peripheral placental separation: a possible relationship to premature labor.

This investigation was undertaken to determine the relationship, if any, between peripheral placental separation and idiopathic premature labor. Ninety placentas from prematurely delivered patients (who had had no antepartum bleeding) were examined grossly and microscopically. Criteria for antepartum peripheral placental separation included adherent clot, with fibrin deposition and lamination, as well as polymorphonuclear infiltration and marginal decidual necrosis. Forty-nine placentas showed unequivocal evidence of previous peripheral separation. Another three placentas showed presumptive evidence of previous peripheral separation. It is suggested that this separation is of venous origin, and that it may play a role in the process of premature labor. This is not necessarily a cause and effect relationship.