Uterotonic agents increase the uterine tone and contractions. These agents intensify uterine muscle contractions at the beginning and during labor, and during the postpartum period. Oxytocin, a hormone produced by the posterior pituitary, is a natural uterotonic.
  Uterotonic agents are used to induce labor and for elected abortions. They lessen blood loss during childbirth and are extremely important in the prevention and treatment of postpartum hemorrhage.