Originally Posted by Xema
If this Wiki
is accurate, then it's fully plausible that a rough fall could precipitate a miscarriage that was already somewhat likely.
I don't think that necessarily follows. "High impact" in the case of exercise doesn't have anything to do with a physical trauma, unless you think they are talking about full contact hockey. They are more likely talking about repetitive stuff like aerobics.
From the "about" pages
Question: Can Falling During Pregnancy Cause a Miscarriage?
The answer is not often at all in the first trimester. In early pregnancy, the uterus is low in the pelvis and very well protected by the mother's pelvic bones. In the first trimester, falling down stairs during pregnancy or experiencing a similar physical trauma would be unlikely to affect the baby or the placenta.
Later on, direct abdominal injury seems like it could cause a miscarriage, but I still don't know how much of a likely event it is.