I don't think you can prove that any one thing "causes" miscarriages, since they are so common and there are so many reasons it can happen.
That being said, a lot of fertitility doctors put their IVF patients on baby aspirin during IVF cycles to *prevent* miscarriages and there are studies that show women who were on aspirin during fertility cycles have slightly better success rates than those who weren't.
This is only anecdotal, I've had 2 pregnancies now where I started low dose aspirin as soon as I got a positive test and so far they've both been successful.My MFM didn't really want me to start the aspirin before a positive test just in case it could interfere with implantation, but my fertility doctor wasn't worried about me taking it throughout the cycle.
Me (29) DH (30)
#1-Olivia Caetlyn-9-28-09-9-28-09, 23+2 wks, emergency classic c-section, class I HELLP, IUGR
#2- Lucas Oliver (rainbow baby)- April 2011, 36+2 wks, HELLP and pre-e free! (lovenox and LDA pregnancy)
#3-Matthew, late October 2012...mostly normal, 37 wks, (lovenox and LDA again)
My blog: http://www.butterflies-and-rainbows.blogspot.com/