Vets conducted an ultrasound on the panda, Mei Xiang, and detected tissue consistent with fetal development.
They say the 22-year-old panda could give birth with the next few days, after imaging revealed what appeared to be a fetus.
Mei Xiang, a resident giant panda at the zoo, has had a team of experts supporting her since she was given artificial insemination in March.
The giant panda has already had three surviving cubs: Tai Shan, Bao Bao and Bei Bei.
Zookeepers are watching her closely and welcoming everyone to watch along on the zoo's panda cameras.
WATCH HERE.