I am sure Nikola will answer this herself when she sees the post but I just wanted to say I started taking aspirin when I started my treatment. The only other thing I took with it was folic acid.
My consultant said that if I was determined to take it I could (which I did!) and to start taking one a day after ET. I also took (and am still taking) Santanogen Pronatal. I carried on with the asprin until I was 16 weeks - I should have stopped at 12 weeks but I was going on honeymoon (belated thanks to the twins!) and because its a 14 hours flight they told me to carry on until I got back. So I've stopped now and fingers crossed all is still ok.
Sometimes you just need something else to hang on to on your second attempt - do you know what I mean? I felt because I was doing the same drugs, some dosage etc, I needed to voluntarily do something else different. Ironically my second cycle was no where near as productive/successful in terms of producing eggs/embies (I only got 6 eggs and the first time I got 14, 4 fertilised but were only grade 2.5 and 3!) But it just goes to show if its your turn, its your turn!
Fingers crossed its yours too! I'd take the asprin just for your own peace of mind.