Luteinized cystic ovarian hyperplasia (LCOH) is a rare benign condition characterized by bilateral ovarian enlargement during pregnancy secondary to high maternal human chorionic gonadotropin serum levels referred to occur under several conditions. We report the case of a 29-year-old obese woman with LCOH incidentally discovered during cesarean section of a single pregnancy at 35 weeks of gestation for fetal intrauterine demise. The fetus showed external ambiguous genitalia, imperforate anus, bilateral dysplastic kidneys, and hydrometrocolpos secondary to atresia of the vagina. The placental weight was 1,450g (normal for gestational age: 415g). The placenta showed diffuse chorangiomatosis (CM) characterized by multifocal stem villi enlargement containing increased number of small vessels with alpha-smooth muscle actin positive cells in the walls in a dense reticulin fibers-rich stroma. The combination of LCOH and placentomegaly due to CM appears to be unique.