Background: Placental cysts are uncommon and generally small. They rarely compromise blood flow and cause fetal growth retardation. Case Report: We are reporting a case of a primigravida who was found to have a large placental cyst during labor. The patient also exhibited oligohydramnios, with an amniotic fluid index of 4. An ultrasound revealed a sizable cyst measuring 4.7×4.8 cm. A male child with low birth weight was subsequently delivered. Conclusion: This case report highlights the importance of monitoring fetal development during pregnancy and considering the possibility of placental cysts when abnormal findings are detected.