A luteoma is a benign ovarian mass that can have malignant characteristics on sonography. Pelvic sonography is used to help distinguish benign from malignant masses. The workup of adnexal masses during pregnancy may involve the use of both transabdominal and transvaginal sonography as well as Doppler imaging, magnetic resonance imaging, and serum tumor markers to identify the risk of malignancy. This study presents a case of a benign ovarian luteoma of pregnancy detected during sonography. The mass was removed during the first trimester due to malignant sonographic features. Counseling and treatment regarding ovarian masses should consist of a multidisciplinary team made up of physicians in maternal-fetal medicine, radiology, neonatology, and sonographers.