The female panda at Washington's National Zoo gave birth to a cub about 10:46 p.m. on Sunday.
The new baby was somewhat of a surprise to zoo officials, who suspected but could not confirm if Mei Xiang was pregnant.
Mei, 14, had been artificially inseminated in late April after she and the zoo’s male giant panda, Tian Tian, 15, failed to mate successfully on their own.
Mei gave birth to her only other cub in 2005. She has had sevral false pregnancies since.