Lovenox is a blood thinner otherwise known as low molecular weight heparin. I have idiopathic thrombophilia, which is a fancy way of saying my blood clots too quickly, but they haven't found a specific cause for it. I'll have to give myself daily injections of it. I was told recently that I would need it throughout the whole pregnancy and for the first six weeks postpartum and that I would need to start the shots at six weeks. But now that I'm pregnant they are doing the "maybe you need it and maybe you don't" thing. They are going to wait until around six weeks to decide and then go from there. For now I'm just on 81 mg of aspirin and hoping it's adequate. I also have small blood vessels so adequate blood flow to my uterus is a potential concern as well.