Do unruptured aneurysms grow during pregnancy?

Hi, I'm a little desperate for info given my extremely rare situation. I had AVM surgery in July 2013 during pregnancy (29th week). They also found a possibly related 2 mm aneurysm that was not treated. I have not had a follow up scan yet. I was given lots of reassurance about the aneursym either shrinking or remaining stable. I'm now realizing that I was being compared to the non-pregnant population. Wouldn't the high volume of blood during pregnancy create a problem for unruptured aneurysms? I've read reassuring information about how women can get pregnant and deliver vaginally with unruptured aneurysms. Does that mean that pregnancy doesn't cause aneurysms to grow either?

I'm confused since high blood pressure seems to be a major risk factor for growth/rupture. I might be misinformed but isn't turbulent pregnancy blood flow very similar to high blood pressure?

I was going to wait until January for my check up so I can enjoy the holidays. Now I'm concerned that pregnancy alone might have caused a major growth over a year ago. Without my realizing. I worry that my doctor was just comparing me to non-pregnant people. They would have more stable blood flow after AVM resection than a pregnant person would.

Please help. I'm in a small minority and can't find any information.

Bless :)

Hi Joy,

Your question makes sense to me but I bet it's too technical for this group to answer. Also, each person's body can vary from whatever the norm is. I would send an email about this to your doctor's office. It's a valid question and you deserve a complete answer.


Hi Joy,

I just had an aneurysm clipped a few weeks ago. I had many questions for my neurosurgeon about pregnancy and aneurysm growth. I had a 4mm MCA aneurysm and I could watch/wait or treat it. My surgeon told me that pregnancy with an aneurysm is completely safe, but that the risk of growth/rupture did increase (VERY slightly, risk is still very low). You're exactly right- it has to do with blood volume. Labor/delivery isn't supposed to pose any additional risk.

As I wanted to be able to have children worry free, I went ahead with the surgery. My surgeon assured me that I could have proceeded with pregnancy either way.

Hi Joy

Having read your post I do not believe that there is anyone on any of the BAF sites that can answer your question with a degree of accuracy, other than a qualified medical team.

I would seriously suggest that as you are pregnant and in certain circumstances that can lead to increased blood pressure, you should consult with your GP, your Gynie and your brain specialist collectively.

Each one of them must be made aware of the fact that you have a brain aneurysm, however small it may be (2mm) that is not the issue! they all need to be aware of this fact.

The fact that you are Pregnant and have a aneurysm may lead your Specialists to recommend a different way of giving birth to your child as a result of an aneurysm, but as I say, you need to talk to your medics.

Please do not be afraid, which is normal in these circumstances, 2mm is tiny in the scale of thing and is very low risk, but talk to your medics and they will give you the best advice.

Please keep us informed at to how it goes after talking to them all, as we will all be interested in their comments and opinions.

Best regards and wishes!


Congratulation for your pregnancy, may the Lord keep you both safe and healthy through it all. Wow! That’s a good question and I hope you get great answers. I also plan to get pregnant in the future, I have already 2 annies treated in 2013 and still have the 3rd and last annie pending!!! Praying

Hi, Joy: I can't answer your medical questions about blood volume and blood pressure, but I can share my info. My aneurysm burst when my daughter was 14 months old. I have no idea if they were related, but I've always wondered. I had a 10 hour labor with a whole lot of pushing. Now they tell me that I can't have constipation because pushing stool increases the risk of any aneurysm growth. Hmmm... They didn't know I had an aneurysm when I was pregnant (no one did), but I had mild high blood pressure (and high blood pressure is a risk factor for rupture) but it went away after her birth. There are a lot of unknowns in aneurysms, so it may be that even your doctors do not know for sure about this. I have a very strong family history of aneurysms, and it's possible the aneurysm and the pregnancy were unrelated, so YMMV. If your insurance will oblige, having an MRI might answer the question and relieve you of anxiety and let you enjoy the holidays.

Hi Joy, My aneurysm ruptured 5 mos. post pregnancy. The doctors said I was lucky it didn't rupture during childbirth because BP is often increased during pregnancy and labor. I was under a MD's care the previous year and had no symptoms or complaints. I had a craniotomy and clipping and did have 2 more children. The only consideration was to not allow for a prolonged labor (to keep BP normal). Keep in mind this was circa 1986. Best of luck

Thank you all, I'm actually not pregnant now but was last year. I had 2.5 months left of pregnancy when they surgically removed my AVM so I worried about growth in between surgery and birth. I had very low blood pressure throughout the remainder of my pregnancy and had a c-section so didn't have to worry about straining. I was told by my high risk OB that a vaginal delivery was possible but my neurosurgeon insisted on c-section which made sense to me. Better safe than sorry and it went very well. I know that nobody can answer this. I actually don't even think my surgeon can answer since this is so rare. I just hope and pray that I still have a chance that this aneurysm is still small. Thank you all!

@Kit34, I've heard similar things. I've also seen studies that say pregnancy does not hold a significant risk for rupture but they didn't mention growth. I guess that might be assumed. I'm glad you could have had babies either way! I hope that dream comes true for you. I'm so thankful my son made it through this with me.

In 2005, My 35 year old daughter had a healthy baby boy. After many years of not being able to get

pregnant, my daughter had a huge AVM repaired and within 6 months she found herself pregnant.

Her OB/GYN often said that she believed it had to due with the better blood flow after the AVM repair.

They treated her pregnancy as high risk and she had a C-section, her OB/GYN, and neuro surgeon did not want her to take any chances with the strain of labor and vaginal birth so the doctors insisted on C-Section. Her pregnancy and delivery went fine and everything worked out no complications. She is still fine and no problems with her AVM. I now have a beautiful and healthy nine year old grandson.

AVM was not in the brain, it was quite large and at the base of the brain, on the internal carotid artery

as is entered the brain. So please check with your doctor, and if you still feel uncomfortable seek advice

from another doctor.

The best advice here is to talk or write out concerns with your neurosurgeon/neurologist and to get a second opinion, if you are still unsatisfied with the answers.

Even during pregnancy, there is a "normal" range for blood pressure and no two cases are alike. Too high a BP can lead to eclampsia, a dangerous condition.

Hope this will reassure you a little: I had an aneurysm rupture during my fifth month of pregnancy some 45 years ago. Had nine hours of surgery to clip it. It ruptured again during surgery. My son was born naturally two months later after a short labor (characteristic of women in my family). Apparently, there was a discussion among the obstetricians about the method of delivery -- this was in a military hospital. One OB told me I was to see a certain OB for checkups because "he is the only one brave enough to let you deliver naturally."

My son was early, but weighed 6 lbs. 12 oz. and the only wrinkle was him having phisological jaundice (not related to the aneurysm rupture/surgery and not uncommon in newborns). I had a second child 3 1/2 years later and the subject of the aneurysm never came up.

Maybe because it was so long ago, doctors seem pretty unconcerned about the aneurysm rupture until recently when I had seizures that were diagnosed as simple, focal epilepsy, but not related to the aneurysm.

Don't worry about anything that may never happen. Good luck to you.

Martins advise is perfect. FWIW you are correct blood volume increases during pregnancy, A healthy woman bearing a normal sized fetus, with an average birth weight of about 3.3 kg, will increase her plasma volume by an average of about 1250 ml. Thats PLASMA volume. You get very little increase in platelets. There is even a formula for it. about 90ml per KG of weight gain...... It increases linearly after the first trimester. As you get bigger the blood volume goes up. They will monitor your BP very closely throughout the pregnancy

You need to really watch your weight during your pregnancy. None of this snacking "to feed baby" stuff. They may very well as several have mentioned consider C-section for delivery and do so before active labor. That is likely a decision that will not be made until the last bit. There is a lot to be said (as my daughter would say) for having babies the "old fashioned way" - unconscious. You may want to talk about those issues with a birthing coach and ask your doctors. natural isn't always better....

You're going to be fine in any event and in case it hasn't been said enough congratulations. Please enjoy this miraculous time..... Talk to whoever you need to to make it as special as it is.