There is research that says aspirin can cause miscarriage but the risk is very low & lower still when the 75mg dose is taken to prevent PE. Most of the research suggests it is the normal adult doses that increase the risks further.
Interestingly there is increasing research to show that low dose aspirin may help women who experience repeated miscarriage, particularly if there is an underlying 'sticky blood' syndrome.
I also came across a very interesting study which discussed low dose aspirin & increased dietary omega 3 fatty acids help improve the blood flow velocity across the uterine arteries, although more study is needed to see if improves the out come of the pregnancy.http://www.ncbi.nlm.nih.gov/pubmed/18692841?dopt=AbstractPlus
Hope this helps.
Every Woman is entitled to understand what happened in her pregnancy when pre eclampsia strikes. I hope to be able to support that process.