Impact of pregnancy on the size of small cerebral aneurysm

Because the management of cerebral aneurysms during pregnancy remains controversial, the objective of this study was to perform a retrospective review of pregnant women with cerebral aneurysms to determine whether pregnancy is a risk factor for aneurysm rupture.

The change in size of aneurysms during pregnancy was examined by performing repeat magnetic resonance angiography in five pregnant women with cerebral aneurysms between 2005 and 2013. The outcome examined was development of subarachnoid hemorrhage.

Among the five pregnancies, there were eight cerebral aneurysms. Subarachnoid hemorrhage did not developed during any pregnancy. In four of the pregnancies, the cerebral aneurysms did not change in size during pregnancy, remaining 2-5 mm. Although in one pregnancy, the aneurysm increased from 6 to 7 mm during the third trimester, it returned to its original size in the postpartum period.

We suggest that if the cerebral aneurysm is small (≤ 5 mm), it is likely to remain unchanged despite the increase in circulating blood volume during pregnancy. Cerebral aneurysms greater than 5 mm but without blebs, irregular shape, high-risk location, or increased aspect ratio are also at low risk of rupture and are not likely to change during pregnancy.