Odd question

Britanny • Married to my high school sweetheart. Mom of 1. TTC #2 and having zero luck.
I read in one of these forums that women were pumping breast milk in order to start up labor and contractions. Is that something that is real? I was under the impression that you can't start pumping until after the baby is born because there's nothing to pump... Has anyone tried this? First time mom so I have no idea what is possible..