Once your cervix is ready (and if you aren't having contractions yet), Pitocin comes through an IV in your arm. A pump hooked up to the IV tube controls the amount given, explains ACOG.

Archive Rupture of the Uterus during Pitocin Infusion Authors: James Henry Ferguson, M.D., George T. Schneider, M.D., and Henry K. Miller, M.D. Author Info & Affiliations Published May 1, 1952 ...