formation of yellowish white or bloodstained deposits of fibrin (a fibrous protein) on the surface or in the substance of the placenta, the temporary organ that develops during pregnancy to nourish the fetus and to carry away its wastes. Formation of placental infarcts is normal during the later stages of the organ's development. The term infarct, which usually signifies an area of dead tissue, is loosely used in this instance. Although extensive placental infarcts are sometimes present in stillbirths and in instances of premature separation of the placenta from its implantation site in the wall of the uterus, the infarcts are thought by most gynecologists and obstetricians not to be the causes of the other abnormalities.