SAN DIEGO: The most prolific giant panda in captivity outside of China, Bai Yun, has proved her mettle yet again with the delivery of her sixth live cub at the San Diego Zoo.

The unnamed baby panda weighed about four ounces (113 grams) at birth.

The 20-year-old panda's pregnancy was considered high risk because of her age, but Bai Yun and the new cub are in seclusion during "a critical bonding period."