She may meow throughout the delivery. If it helps her feel better you should stay with her and she will stop when she no longer feels the need to meow.
Iliotibial band syndrome, knee bursitis, runner's knee, osteoarthritis and patellar tendonitis can also cause knee pain when bending. Other causes of knee pain.
A Folk song that uses A. Guitar and Acoustic Drums to emote its Chill and Contemplative moods. License When It's All Said and Done - Instrumental by Drew.