Absent Moro reflex on the affected side indicates a possible injury to the brachial plexus, which is the nerve network that controls the movements and sensations of the shoulder, arm, hand and fingers. Shoulder dystocia can cause brachial plexus injuries when the baby’s shoulder gets stuck behind the mother’s pubic bone during delivery.

Choice B is wrong because flaccid paralysis of both lower extremities is not a common complication of shoulder dystocia.

It could be a sign of spinal cord injury or other neurological disorders.

Choice C is wrong because facial asymmetry when crying or smiling is a sign of facial nerve palsy, which can occur due to compression of the facial nerve during delivery.

It is not specific to shoulder dystocia.

Choice D is wrong because inability to suck or swallow is not a typical sign of shoulder dystocia.

It could be caused by other factors such as prematurity, neurological problems, or congenital anomalies.

Normal ranges for Moro reflex are present at birth and disappear by 4 to 6 months of age.

Normal ranges for facial nerve function are symmetrical movements of both sides of the face.

Normal ranges for sucking and swallowing are coordinated and effective feeding within the first hour after birth.