Introduction: Cerebral venous thrombosis with cerebral haemorrhage is relatively rare yet can result to fatal outcome. Antithrombin III deficiency is one of the inheritable coagulable states that contribute to an increase in thromboembolic event during pregnancy.

Objective: To evaluate the risk of pregnancy-associated venous thromboembolism in women with antithrombin III deficiency.

Case Report: This is a case of 34 years old, pseudo-primigravida at 9 weeks of gestation, with underlying antithrombin III deficiency and currently on treatment dose of low molecular weight heparin, presented with sudden episode of frontal headache associated with projectile vomiting side. A plain CT and MRA/MRV brain showed features suggestive of CVST involving superior saggital sinus with venous infarct and right frontal and left parietal intraparenchymal haemorrhage. Subsequently, patient had fitting episodes and loss of consciousness and further assessment noted unequal pupils. A repeated CT brain showed worsening intraparechyma hemorrhages with midline shift, subfalcine herniation and cerebral oedema. Therefore, an emergency bifrontal craniectomy was performed to relieve the intracranial pressure. Despite the operation and supportive measures, patient succumbed to death due to rising intracranial pressure.

Conclusion: Due to highly thrombophilic state of pregnancy with concomitant antithrombin III deficiency, administration of antithrombin III concentrate, in addition to anticoagulation, should be considered during pregnancy and puerperium to women with documented antithrombin deficiency.