OP here. that's the thing, I've ready up on them and there is zero evidence they help prevent stillbirth. There is also zero evidence that placental quality is the reason for increased stillbirths associated with AMA. The only thing that does have some solid evidence is that induction at 41 weeks or so, and then it would take nearly 10,000 inductions (9630 if I recall) to prevent one stillbirth.
This does a decent job of summarizing available studies, but I dug into some of the studies on top of this too...
https://evidencebasedbirth.com/advanced-maternal-age/