Increases in postimplantation loss, reduced foetal body weights and decreased litter sizes together with increases in the number of malformations (gross external, soft tissue) and skeletal alterations (including retarded ossification) were reported in rats receiving doses which produced approximately 2 to 3 fold the clinical exposure (54 mg/ m2/ day) and in rabbits receiving 12 mg/ m2/ day clofarabine.