Chronic intervillositis of unknown etiology (CIUE) is a rare condition that affects the placenta, the organ that connects a mother and her unborn baby. It is characterized by inflammation of the intervillous space, the area between the maternal and fetal blood vessels in the placenta. The cause of CIUE is unknown, but it is thought to be an autoimmune disorder. Symptoms of CIUE include preterm labor, intrauterine growth restriction, and fetal death. Treatment typically involves corticosteroids and other immunosuppressive medications.