A conjunction pattern used as XにつれY, meaning that as X changes, Y changes accordingly. Often used for gradual, proportional change. Similar to につれて, but slightly more formal or written.
See also: につれて
As I get older, my physical strength has declined.
As the days passed, the sadness faded.
に伴って describes one event or change accompanying another (not always gradual), while に連れ specifically emphasizes proportional, step-by-step change.
Derived from the verb 連れる (つれる, 'to take along'), but now functions as a fixed grammatical pattern. The kana form is standard.