A giant panda gave birth to a cub at the US National Zoo on Friday, raising hopes for a rare success after a series of false pregnancies and a death.
"WE HAVE A CUB!!" the zoo announced on Twitter, after the birth was shown live on two Internet webcams from the panda's den.
The tiny pinkish-white cub was born at 5:32 pm (2132 GMT), about two hours after its mother Mei Xiang's water broke, the zoo said.
Mei Xiang picked up the cub and cradled it, then began nursing.
"I'm glued to the new panda cams and thrilled to hear the squeals, which appear healthy, of our newborn cub," said zoo director Dennis Kelly.
"Our expansive panda team has worked tirelessly analyzing hormones and behavior since March, and as a result of their expertise and our collaboration with scientists from around the world we are celebrating this birth."
The sex of the cub remains unknown for now.
The birth was the third for Mei Xiang, who along with her male counterpart Tian Tian is on loan to the US zoo from China.
However, no one is yet sure about the father's identity.
Mei Xiang and Tian Tian attempted to conceive a cub naturally during their once-a-year mating ritual this winter.
But after reproductive specialists determined that bid was unsuccessful, they performed artificial insemination using sperm samples from both Tian Tian and another male panda, Gao Gao, who resides at the San Diego Zoo.
"We never did that before because Mei Xiang was inseminated with the semen of one male only," reproductive scientist Pierre Comizzoli told AFP.
The baby's daddy will be revealed after a DNA test is condcuted, possibly as early as in the next day or two, the zoo said.
The DNA sample will be taken during the cub's first neonatal exam, along with measurements of the cub's weight and overall health.
Baby pandas are born in a nearly premature state, fragile, unable to see and about the size of a stick of butter.
The early days of life are particularly precarious for these endangered animals, experts say.
A cub born to Mei Xiang last year died six days later. Scientists said the cub was unable to survive due to liver and lung problems.
The giant panda had five consecutive false pregnancies from 2007 to 2012.
In 2005, Mei Xiang and Tian Tian had a son, Tai Shan. He was the first cub from the National Zoo to reach adulthood, and now resides in China at the Bifengxia Panda Base.
A pair of giant pandas was first donated to the US capital's zoo in 1972, shortly after president Richard Nixon made a historic visit to China.
While many advances have been made in reproductive technology for pandas in recent years, experts are still unsure whether a female is pregnant or is experiencing a pseudopregnancy until the very end of the three-to-five-month gestation period.
The giant panda experiences the same physiological stages whether she is going through a true pregnancy or a false one.
Ultrasounds can be done on pandas but are often inconclusive because of the animals' vast network of bamboo-digesting intestines and fatty tissue, making a tiny fetus hard to detect.