AVM versus Aneurysm

Hi, I was wondering if anyone knew why it's generally believed that pregnancy can cause AVM rupture but often does not cause aneurysm rupture? Can anyone explain how these lesions differ when it comes to blood flow/cardiac output in pregnancy? Thank you :)

Hi, Dee, I did a little research on this topic and also checked our aneurysm community. A 2013 study suggested that pregnancy does not raise the risk of aneurysm rupture, though it was previously believed that it did. However, I think some caution makes sense, and if I were pregnant with an aneurysm, I would be taking my doctor's recommendation about whether or not to attempt labor and delivery, as annies, likes avms, vary a lot among individuals. I have not been able to find any information about whether pregnancy may cause annies to grow or progress, though there is a fair bit of evidence for that with avms. (For many of our female members, avms first become clinically significant during pregnancy.) Blood volume increases during pregnancy, and bp may rise, though it is not a given. Keep talking to your doctors about this important topic, and share with them the questions you have raised here. If you get additional information, please check back in and share it with us.


Great question! I knew that it's believed pregnancy can encourage the regrowth of an AVM, but I had read that pregnancy does not necessarily increase the risk of an AVM rupture. From the few studies I've seen, apparently there are changes in the blood vessels during pregnancy (usually late gestational as opposed to first trimester) as well as coagulation factors that can affect the likelihood of a rupture. I did find a study here on AVM ruptures and pregnancy:


Here is an interesting quote from the discussion section of the study:

we found that
the AVM rupture occurred more frequently in late
gestational age. This may be correlated with the more
extensive changes of hemodynamic parameters, coag-
ulative function, and vessel wall in the third trimester.

This is just a short summary that states there is a greater risk of a rupture for women who are pregnant and who have an AVM than for women who are not pregnant:


Here is a study on aneurysms during pregnancy:


and one more focusing on aneurysm and pregnancy:


Hope this helps!

Wow! Thank you! This was very informative :)