Giant panda at National Zoo gives birth to cub: 'A much-needed moment of pure joy'

It's panda-monium amid pandemic.

In a refreshing bit of good news out of Washington, Mei Xiang, the giant panda matriarch of the Smithsonian's National Zoo, gave birth to a cub Friday and immediately began cradling and caring for it, zoo officials said.

"A precious giant panda cub has arrived! We’re overjoyed to share that Mei Xiang gave birth at 6:35 p.m. and is caring for her newborn attentively," the Zoo tweeted Friday.

The zoo encouraged people to tune in to its "Giant Panda Cam" page to see Mei Xiang and the cub. However, some social media users were greeted with an error message less than an hour after the zoo announced the news.

Zoo officials say they are monitoring the mother and the new cub using the cams. It may be several days before zookeepers retrieve the cub to perform a neonatal exam, and the cub's sex will be determined in the future, the zoo said in a release.

At 22, Mei Xiang is the oldest giant panda to successfully give birth in the United States. The oldest in the world was 23.

Her age made the chances of having a cub "slim" — but zookeepers "wanted to give her one more opportunity to contribute to her species’ survival," zoo administrators are quoted in a release.

"Giant pandas are an international symbol of endangered wildlife and hope, and with the birth of this precious cub we are thrilled to offer the world a much-needed moment of pure joy."

Already a mother to three cubs that survived, Mei Xiang was artificially inseminated by zookeepers back in March with sperm from Tian Tian, her male counterpart at the National Zoo.

Pandas "experience a phenomenon referred to as delayed implantation," the zoo said in a statement when they announced her pregnancy on Aug. 14. That means an embryo may not attach to the panda's uterine wall for weeks or months, and once it does, it grows exponentially, the zoo says.

Previously: A giant panda at the National Zoo is about to give birth. Watch for these signs of labor on the 'panda cam'

While stillbirth or miscarriage were possibilities, zookeepers were cautiously optimistic that Mei Xiang would give birth successfully after seeing the fetus develop in another ultrasound earlier this week.

Mei Xiang came to D.C. in 2000 alongside Tian Tian.

Pandas have been at the zoo almost continuously since 1972 when pandas Ling-Ling and Hsing-Hsing first arrived to Washington as a gift from the Chinese government. The pair lived at the zoo for 20 years but never had viable offspring before they died in the 1990s.

Since Mei Xiang and Tian Tian's arrival, the zoo has welcomed three other cubs: Tai Shan, born in 2005, Bao Bao, born in 2013 and Bei Bei in 2015.

All three currently live in China as part of an agreement with wildlife officials there, and under the zoo's current agreement, all cubs born in Washington are sent to China around age 4.

Zoo spokeswoman Pamela Baker-Masson said that while that agreement ends in December, the zoo is working on renegotiating new terms.

"Our team in collaboration with our Chinese colleagues wouldn’t ship any panda unless everyone felt comfortable that it was safe and in the best interest of the animal," she said.

Mei Xiang and Tian Tian are also slated to return to China in December under the agreement, but Baker-Masson said both sides will discuss and act in the best interest of the animals.

The breeding program and exchange between China and zoos around the world has largely been heralded as a success. For decades, the species was considered "endangered" and only recently was recategorized as "vulnerable" by the IUCN Red List of Threatened Species.

Contributing: The Associated Press

Follow USA TODAY's Ryan Miller on Twitter @RyanW_Miller

This article originally appeared on USA TODAY: Panda at National Zoo in Washington gives birth to cub