Final answer:
Terbutaline is the least expected medication to be administered for postpartum hemorrhage, as it is used to relax uterus muscles, not contract them. Medications like carboprost, oxytocin, and methylergonovine are used to control hemorrhage by contracting the uterus. Oxytocin plays a key role in labor by causing uterine contractions.
Step-by-step explanation:
A nurse would least expect to administer terbutaline to a woman experiencing postpartum hemorrhage among the options given. Terbutaline is a medication that is used to relax muscles and prevent preterm labor; it is not used to manage postpartum hemorrhage. The other medications listed - carboprost, oxytocin, and methylergonovine - are all uterotonic agents that help contract the uterus to prevent or control hemorrhage.
Oxytocin is the hormone primarily responsible for contractions during labor. Prior to the expulsion of the baby and placenta, the posterior pituitary gland produces oxytocin, which is sufficient for muscular contraction in the uterus to facilitate birth.