Baby aspirin

I’ll be 40yrs old in a couple weeks and am almost 20weeks pregnant. My doctor told me I should start taking a baby aspirin everyday simply because of my age. I have never had high blood pressure or any other complications or symptoms of preeclampsia. I started taking it, but have a lot of concerns since it’s simply because of age. I didn’t think of asking this at the appointment, and just curious if anyone else has thoughts on this?