Hi Katesmom, welcome to the group. I hope you find someone in your exact situation, as I don't speak aorta and don't even know how significant a 45mm aneurysm is. But for what it's worth . . .
I had three babies before finding out that I had mitral stenosis which was revealed when I got pregnant with twins. No problem first three, then problems with the twins that revealed the heart issue. So I think you could completely sail through again just like when you were blissfully unaware, or you could have issues all dependent on the current state of your valve and aorta, if that makes sense. Not sure what symptoms you may be having that led to your dx now.
I would agree with ottagal that it wouldn't hurt to see if consulting with a perinatalogist (high risk pregnancy doc) would make sense for you - that's who delivered my twins. He/she has probably dealt with your situation many times and can tell you what the risks may or may not be for both you and your baby and help you make the best plan in terms of monitoring, delivery method, etc. That doc will also probably be associated with a hospital that has a NICU just in case anything would happen where the baby needed to come early. I'm hoping you live near a metro area to make this option feasible for at least a consult.
Congrats on your lovely family.