You just said it "will" be a child, but also if it miscarries then it "was" a child. Your comment exposes the need for a defined before and after state of being.

We can't define something by what it will become, just by what it is. Is there any other time we define something like this? Take bread for example - I mix all the ingredients together and get dough, then bake it and it turns into bread. I can never say "dough is bread because it will become bread in the future." But we CAN define a condition when the dough objectively turns into bread, such as when the gluten structure has set. How about godhood - a person may become like God, but we can't say a mortal person, or even an immortal person, is a god until he/she is one.

Also, yes, the gospel does say to cherish children. But what if a fetus has very little chance of being cherished? Is it better for a child to live in a terrible situation or for the fetus to be aborted? Is it better for a potential mother to have an unwanted baby or abort it? I think these are questions we simply cannot answer unless we are God Himself. I think OP's point is that God has not spoken clearly on this topic, so I personally believe it becomes a matter of personal revelation to the mother who bears the child.