Zookeepers hope giant panda Mei Xiang could soon deliver a panda cub at the Smithsonian National Zoo. It's rare for panda cubs to be born in captivity. In the U.S., fewer than a dozen giant panda cubs have been born in zoos.
One of them was actually Mei Xiangs previous cub, born in 2005. The panda was named Tai Shan and is now in a China breeding facility.
"It was monumental when he was born," said the Zoo's Chief Veterinarian Dr. Suzan Murray.
"He was really strong. We're hoping for a repeat performance... If anyone can do it she can."
Using sperm from companion Tian Tian, the 12-year-old panda has been artificially inseminated seven times, but none of those attempts were successful.
Mei Xiang is kept away from visitors for now. She's on 24-hour watch, and zookeepers see via cameras that she's building a nest. Tests show elevated hormone levels consistent with pregnancy.
All giant pandas are on loan from China. If Mei Xiang has a cub, it would be able to stay at the Smithsonian Zoo for a couple of years. Then the cub would be sent to China.