While we're not explicitly told that "Metaphors" takes place in a different world or dream reality, there's not much of the real world coming through in this poem. We have to break through a metaphorical version of reality to find it. Through metaphors, this poem sets up a different universe, which connects back to the real world in surprising ways. It's important to see the world that the poem has literally created, sure, but it's also important to see how this imaginary world links back to the real world of this pregnant woman's life.
The metaphors in this poem establish an alternate reality that sheds light on the real world.
This poem shows that being pregnant can shift a woman's reality.