Like, for example, what if in one hypothetical case, a woman went skiing in mid-2nd trimester (gee, don't know anyone who would do that, I say while rolling my eyes upwards), and while walking across the icy parking lot, slipped and fell on the ice on her side, causing minor placental abruption due to trauma, not genetics. Thinking everything was fine, she went about her life, but the hypoxic cascade had started, and 9 weeks later, she delivers early due to fetal indicators. Figuring out whether the fall and trauma was the cause, or whether it was a shallowly implanted placenta from the start due to underlying genetics, isn't as easy to figure out as it sounds, and the prophylaxis (if any) might be completely different between the two triggers. In the trauma case, being on blood thinners might actually make things worse.
I don't wanna do lovenox again! (I say in my whinyest little toddler voice). I just wanted to know for a more up to date picture of risk vs. benefits that was not based solely upon pain and expense, so I could discuss such things sometime sooner rather than later with my OB who is generally clueless about the latest research. It's my health, ya know.