Final answer:
The most appropriate nursing intervention for a new mother with low blood pressure and a high heart rate immediately postpartum and with concern for tissue perfusion is bleeding reduction.
Step-by-step explanation:
The nursing intervention that is most appropriate for a new mother with a low blood pressure of 70/49 and a high heart rate of 126 immediately postpartum and with concern for tissue perfusion is Bleeding reduction. This is because a low blood pressure combined with a high heart rate may indicate postpartum hemorrhage, which can lead to decreased tissue perfusion. By focusing on reducing bleeding, the nurse can help stabilize the mother's blood pressure and improve tissue perfusion.