Two Blue Lines

My sister-in-law had her positive pregnancy test framed and hung on the wall of the baby's bedroom... is it just me who finds that a tad gross?

However, the whole matter-of-factness of this poem really appeals to me.  Phrases like "plastic prophet" and "chemical wisdom" are wonderful.  

Starting the second stanza with "should", though it's grammatically correct, actually sounds like you're asking a question right up until the last line there and that threw me off at first reading.  You might like to consider "If I listened more carefully" instead.  You do have a couple of superfluous words, for example "And to the subtle nuances in the tides of my body" would be better as "and the subtle nuances in the tides of my body" or "and the subtle nuances in my body's tides".  Additionally, what would you think of "which manifests as two blue lines" instead of "Which comes in the way of two blue lines"?

All things considered, though, I like the tone and for the most part the execution of the poem -- though it's a shame they can't figure out a better way of testing, peeing on command (and on your hand) is no fun.