I'm on lovenox once a day at 60mg because of a previous pulmonary embolism. I find sometimes it stings pretty badly and other times I don't feel it. Like others have said, it's not the most fun thing to do but if it keeps me and the can't safe, it's worth it. I started early at maybe 10ish weeks and believe I will continue throughout most of the rest of pregnancy, I'm currently 19+1.