Final answer:
The most suggestive abnormality of hip dislocation following a breech delivery is a lengthened leg of the affected side.
Step-by-step explanation:
When assessing a newborn following a breech delivery, the nurse should be looking for signs of hip dislocation. The most suggestive abnormality in this case would be lengthened leg of the affected side. In a normal hip joint, the legs should be symmetrical in length. If one leg appears longer than the other, it could indicate a dislocated hip.