Final answer:
Teaching the woman the importance of rest and nutrition is the least effective in preventing postpartum hemorrhage; while rest and good nutrition aid in healing and recovery, they do not directly help in the immediate contraction of the uterus to prevent bleeding.
Step-by-step explanation:
To prevent postpartum hemorrhage, various measures are employed. Administering Methergine 0.2 mg every 6 hours for 4 doses can encourage uterine contractions, helping the uterus to regain its pre-pregnancy size and to control bleeding. Encouraging the woman to void every 2 hours can help prevent urinary retention, which can displace the uterus and potentially hinder uterine contraction, thus contributing to hemorrhage control indirectly. Massaging the fundus every hour for the first 24 hours after birth is a direct method of stimulating uterine contractions, reducing the likelihood of hemorrhage. However, teaching the woman the importance of rest and nutrition, while valuable for overall healing and recovery, is the least effective measure in the immediate prevention of postpartum hemorrhage.