Do avm's always burst in pregnancy and what are the chances? can i get a mri to make sure i don't have a avm?

Brain AVM: A brain arteriovenous malformation (AVM) is rare and they are present from birth. The risk of bleeding is also rare but most commonly occurs between the second and third trimester when blood volume increases. As long as there are no associated aneurysms then vaginal delivery is ok. Headaches are common in pregnancy but that doesn't warrant an MRI study. MRI scans are safe during pregnancy.