We prepared a sample of oxirane doubly deuterated at one C atom and studied its rotational spectrum in the laboratory for the first time between 120 GHz and 1094 GHz. Accurate spectroscopic parameters up to eighth order were determined, and the calculated rest frequencies were used to identify c-CD₂CH₂O tentatively in the interstellar medium in the Atacama Large Millimeter/submillimeter Array Protostellar Interferometric Line Survey (PILS) of the Class 0 protostellar system IRAS 16293-2422. The c-CD₂CH₂O to c-C₂H₄O ratio was estimated to be ∼0.054 with T_rot=125 K. This value translates to a D-to-H ratio of ∼0.16 per H atom which is higher by a factor of 4.5 than the ∼0.036 per H atom obtained for c-C₂H₃DO. Such increase in the degree of deuteration referenced to one H atom in multiply deuterated isotopologs compared to their singly deuterated variants have been observed commonly in recent years.