Collo, over in the LTTTC & AC thread a couple of days ago I asked one of the girls there (minimay) who said she was on Clexane post-transfer why she was on it, as I thought it was only used for blood clotting disorders as well. She informed me that she had been prescribed it to increase blood flow to the uterus to help create the healthiest environment possible in order for the embryo to stick. She mentioned this as treatment option for older women TTC, as in her case.
Her response to my question in the thread is
here.
I'm sure you could PM minimay if you wanted some more info from her.
HTH,
Miss C