This is a circumvallate placenta, which can be seen in about 5% of placentas. This occurs when the chorionic plate on the fetal side is smaller than the basal plate, which is located on the maternal side. The fetal surface has a central depression surrounded by a thickened, grayish-white ring. The fetal surface inside the ring has the usual appearance and insertion of the umbilical cord. The ring is composed of a double fold of amnion and chorion. Placental abruption, fetal hemorrhage, preterm delivery, perinatal loss, and fetal malformations may be increased with circumvallate placentas.