Earlier quoted context omitted.
It could also be that they are sleeping more, which people will try and shoehorn into: "that's a form of stress!" Stress is a buzzword, I'm wary of manhandling the theory too much as counterpoints come up, especially if it involves playing with semantics.
Exactly; stress isn't one clearly defined thing, and the forms do matter: therefore the focus on overall stress isn't that useful.
It's worse than that: "it's stress" is a lexical tautology. By definition anything that causes a miscarriage was a stressor.