My RE started me on baby aspirin when he found out that my previous m/c was a normal girl (i.e. no chromosomal abnormalities).
I had gone to see a perinatologist to get a CVS at 11 weeks. When she did the u/s, there was no hb. She estimated based on the size, that I m/c at around 10 weeks. Well, she did the CVS anyway just to see if there were chromosomal abnormalities because that usually causes m/c's. But it was a normal girl.
I believe the baby aspirin thins the blood ever so slightly as to make it flow better to the uterus/placenta.
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gmom
DD #1 - Alison born March 2002

m/c angel girl in Oct 2002
ttc#2 - Moved from Clomid/Follistim/IUI to straight Follistim/IUI
currently 7dpiui