As part of the optimization of care, ultrasound scans are routine during pregnancy. The result is the more frequent finding of a benign-looking tumor associated with pregnancy. These are most often mature teratomas of the ovary also called dermoid cyst. We report a case of mature ovarian teratoma larger than 60 mm, diagnosed in early pregnancy. The objective of this clinical case is to discuss the pathophysiological mechanisms, prognosis and management in countries under medical care. This case occurred in a primigest, nulliparous 28-year-old woman who did not have a specific medical history. The pregnancy was brought to term without major complications. The mode of delivery was a cesarean section, which gave us the opportunity to perform the cystectomy. In view of this case, we propose that, in the absence of a laparoscopy or a laparotomy for an ovarian cyst associated with pregnancy and when the maternal-fetal condition allows it, therapeutic abstention may be considered. In this case, special prenatal monitoring must be carried out by a multidisciplinary team of obstetrician, sonographer, intensive care anesthesiologist and neonatologist. Apart from complications directly related to the cyst during pregnancy, we recommend a full term caesarean section. This represents an opportunity to perform the cystectomy at the same time of operation.