I just want to point out that Ctrl+Alt+Del is a Aversion to this trope. it goes to a fair bit into the emotional trauma of a miscarriage. Not that it was welcome or well done or anything, Just that it wasn't treated as a lazy undo for the pregnancy

I've just deleted the Only Fools And Horses example because A) the baby was planned, so it wasn't convenient for the characters, and B) it was supposed to be the season finale, so it wouldn't have made much difference to the writers either. I mention this because I don't really know many of the other examples, and if people consider Cassandra to have had a convenient miscarriage, there may be a misconception that this trope applies to any miscarriage.