Hi!
It is true that Reye's can strike at any age, although it is more common in children. The good news is that it is exceedingly rare in anyone--I have never seen a case in 20 years, although I work with a mostly adult population, and a pediatrician would have a different experience. The BAD news is that Reye's syndrome can occur even in patients who don't take aspirin or other salicylates--it can follow a viral illness even in someone who is not taking aspirin.
Only you can decide what is an exceptable risk to you, but, your risk of miscarriage or pre-eclampsia by far and away exceeds the risk of Reye's. HOWEVER it is also controversial how much aspirin reduces the risk of these problems.
Be sure to ask your own doctor these questions too!
If you were my patient, I would probably encourage you to continue the aspirin, but would also understand if you wished to stop.
Good luck!
Dr B