Causation in miscarriage cases

I’m wondering if anyone has run into the issue of when expert testimony is required to show causation in assault resulting in miscarriage cases. In other words, if the state alleges that the defendant’s assault caused the termination of the victim’s pregnancy, when is expert testimony required to prove causation (if ever)?

My jurisdiction hasn’t reached this issue and I’m having trouble getting productive search terms going. We do have law that says experts are required on causation if it goes beyond the ordinary knowledge of jurors, and I’m sure similar law exists in most states, but I’m wondering if anyone here has run into something directly on point.

State’s position is that it’s a reasonable inference the jury can draw. But the allegations don’t involve any strikes to the stomach or a severe beating.