It's supposed to prevent a miscarriage if you have sticky blood, it doesn't flow properly to baby, but doesn't do any harm if you don't have the sticky blood supposedly. Doctors can't seem to officially agree, one of my previous doctors told me after my second MC to start taking it next time I got pregnant, but said not to tell anyone she told me to take it as its not recommended but apparently had high success rates for recurrent mc's. The doctor I seen for my third pregnancy was very anti-aspirin and said not to take it without having had the tests done for sticky blood. I did my own research this time and have decided to take 75mg a day as most say it can't do any harm in such a low dose but could prevent MC.