At this point in our evolutionary progress, the expected human gestation period is (roughly) nine months long. My question is, has this duration of time always been the same for homo sapiens? Or, are pregnancies getting longer/shorter?
My attempts so far: upon searching online, I was only able to find a single reddit thread, of which didn't provide much of anything. And then, on Wiki's page for gestation it provides a link that should contain content on the "evolution of gestation related features for mammals", however, the link revealed itself to just be a page that outlines all mammalian evolutionary developments, and I'm not able to find the forementioned gestation specific information within it.