What is the ruling if a woman claims a man struck her causing a miscarriage, but the man denies the striking?

Primary text

The man's statement prevails, supported by his oath, because the original assumption is the absence of the striking. If the man admits to the striking, or if there is proof against him, and he then denies the miscarriage occurred, his statement prevails with his oath. This is because the occurrence of the miscarriage is unknown, and he is not required to swear definitively concerning the action of another, as the original assumption is its absence.