A 35-year-old woman at eight weeks of gestation in her second pregnancy presented with generalized seizures. Magnetic resonance images revealed a small hemorrhagic infarction in the left frontal lobe, and magnetic resonance venography indicated cerebral venous sinus thrombosis. After hospitalization, anticoagulant therapy was continued, and a low protein C level was confirmed, which was also confirmed in both her mother and her sister. Follow-up magnetic resonance venography performed on day 27 confirmed that the cerebral venous sinuses had undergone recanalization. After a completed gestation period, the patient gave birth to healthy girl uneventfully.