It is associated with an increase of sex hormones, primarily progesterone and testosterone.[1][2] The size of the tumor can range from 1 to 25 cm in diameter, but is usually 6 to 10 cm in diameter[3] and can grow throughout the duration of the pregnancy.[4] However, luteomas are benign and resolve themselves after delivery. This type of tumor is rare with only about 200 documented cases; many of these cases were detected accidentally, so the actual rate of occurrence may be higher.