Final answer:
The best outcomes after obstetric brachial plexus palsy are associated with spontaneous recovery within the first two months, particularly indicated by the return of the Moro reflex and elbow flexion within the first month.
Step-by-step explanation:
The best outcomes after obstetric brachial plexus palsy are generally associated with cases where there is spontaneous recovery of the affected nerves, particularly within the first two months after birth. The brachial plexus is a nerve plexus associated with the lower cervical spinal nerves and the first thoracic spinal nerve, which can be damaged during childbirth, leading to weakness or paralysis of the arm. Recovery is typically measured by the return of muscle function and sensation, and early recovery is often a good prognostic sign. The presence of Moro reflex and elbow flexion within the first month are indicators of potentially better outcomes. The prognosis is worse when there is no spontaneous nerve recovery early on or when there is a rupture or avulsion of the nerves. In such cases, surgical intervention might be considered to improve outcomes.