In addition to tinkering with crops and rabbits, "Piss Prophets" were hot commodities in the 1800s and determined a variety of conditions just by the color of a person's urine. In the 1500’s, pregnancy urine was thought to resemble the color of an off-white lemon with a cloud on its surface.
Sometimes the Piss Prophet would mix up a concoction of wine and urine to see how it would react. Though alcohol can react with proteins in urine and possibly indicate pregnancy, it really just sounds like a waste of wine to me. Hopefully the Piss Prophets used the equivalent of “Three Buck Chuck."