One interpretation of the cabin is that it signifies an entryway into a very different world, one which Nick in particular is very unfamiliar with.  There is a weird sense of detachment as his father doesn't hear the woman's screams "because they are not important."  There is an overwhelming sense of dismissal for the people involved in the actual labor and childbirth.  The cabin itself holds all these events and once the men leave, as George or eventually Nick and his father do, it will be as though they have re-entered their own world, the white world, where things make sense and men don't kill themselves because of a woman screaming.