Final answer:
An LGA newborn with a right arm that remains extended and medially rotated during the Moro reflex may have a brachial plexus injury or a related birth injury, requiring further medical evaluation.
Step-by-step explanation:
When assessing the Moro reflex in an LGA (large for gestational age) newborn, if the right arm remains extended and medially rotated, it could be indicative of an injury or abnormality, such as a brachial plexus injury or clavicle fracture. This injury can occur during birth, especially in LGA infants, due to the increased pressure and manipulation required for delivery. An abnormal Moro reflex suggests that there is an asymmetry in motor function, which may result from upper motor neuron (UMN) lesions, diseases such as cerebral palsy, or injury during birth. A healthcare professional would need to conduct further evaluation to determine the exact cause and appropriate management.