Spontaneous complete chorioamniotic membrane separation (cCMS) is rare and associated with adverse perinatal outcomes, such as intrauterine fetal death. Herein, we present a case of spontaneous cCMS in a fetus with ileal atresia and umbilical cord ulcers. In our case, we detected spontaneous cCMS on ultrasonography at 35 weeks of gestation. On the same day, a female infant weighing 2134 g was delivered via cesarean section. Pathological examination of the placenta confirmed cCMS and umbilical cord ulcers. When cCMS is evident in late preterm infants, the fetus should be carefully monitored and considered for delivery.