A morphological and immunological study of human placental bed biopsies in miscarriage

Placental bed biopsies were examined in three groups of pregnant women for maternal vascular response to placentation as well as for the presence of cells associated with local immunosuppression activity. In the group of women undergoing legal abortion, the histological appearance of trophoblastic invasion was normal in all but one, and the proportion of immunosuppressor cells was also normal. In the missed miscarriage group the histological appearances were abnormal except in one patient. In women with a history of recurrent miscarriage who had miscarried after immunization, placentation was normal in some and defective in others. Immunosuppressor cells appeared to be diminished in number, although there was no correlation between the cytotoxic status of their sera and their pregnancy outcome.