Without commenting on individual cases above, I have sadly have reason to read quite a bit about miscarriage and its causes. It is only extremely rarely caused by accidental impact to the abdomen. Sadly it is common in early pregnancy and can happen without warning, and thus it is very much more likely to be a tragic coincidence. Many women attribute a miscarriage to a physical action (often blaming themselves for a trip) but the cause is often something else entirely.
The preferential treatment for pregnant women is more to do with their exhaustion, balancing issues, sickness, etc. It is still very much deserved.