UPDATE 8/22/2015: A new giant panda cub was born today at 5:34 p.m. at the Smithsonian's National Zoo in Washington, D.C. The birth of the cub was recorded in video on the panda cam (above). The tiny cub, which will not be named for another 100 days following the birth, will live on its mother's chest near the mammary glands or keep warm under her arm for the next few weeks. The pair is being held in seclusion, but interested spectators can tune in to the Zoo’s panda cam to watch the mother and cub’s interactions.

UPDATE 8/23/2015: At 10:07 p.m. last night, about four-and-a-half hours after the first cub was born, Mei Xiang gave birth to a second cub. Read more about this unusual, historic twin birth here.

UPDATE 8/23/2015: Veterinarians at the Zoo conducted an examination of the first cub and released video.

The National Zoo’s online panda cameras, or panda cams, crashed Saturday afternoon after the officials tweeted that the giant panda Mei Xiang might be in labor. Around 3 p.m., Zoo staff placed a sign near the giant panda habitat reading: "Pandas Are Off Exhibit."

At the Zoo, as media trucks began to arrive, few visitors understood why. Emi Suzuki, who just moved to New York City and is in town visiting said she was disappointed that she couldn't see the animals because she had heard that very few zoos have pandas. But Bill Menczer from Washington, D.C., noted that they were probably giving the panda some space to relax and allow her to rest during her pregancy. "I am confident that everything is okay."

Mei Xiang had been exhibiting behavior consistent with labor since this morning, said keeper Juan Rodriguez, who as at the entrance to the panda exhibit. "She's restless, licking her body a lot, and we're on the look out for contractions."

Our panda team believes Mei Xiang is in labor! We’re hoping for a healthy cub. #PandaStory http://t.co/S7WWws1JTy pic.twitter.com/Hs7sp6N5rW — National Zoo (@NationalZoo) August 22, 2015

Panda breeding is complicated and frustrating. But Zoo veterinarians were optimistic that a new panda was on the way when an ultrasound on Wednesday showed a four-centimeter fetus. Mei’s behavior for the past few days—eating less and cradling a branch like a cub—indicated that she might be expecting.

If a healthy cub is born, Zoo veterinarians and biologists will try to get their hands on the cub within 24 hours to measure body length and weight and check for any defects, Dr. Don Neiffer, chief veterinarian at the National Zoo said on Friday. They should also be able to determine the cub’s sex within the first week.

Because protocol prevents staff members from entering the panda’s enclosure without any protection, they must work with Mei Xiang to access the cub. If she refuses to hand over the cub, there’s not much they can do but hope that she finally does.

For the first several days after a birth, keepers have come to know Mei's habits after observing her behaviors following the birth of her previous cubs. Mei will not leave her cub for any reason, not even to eat. She will be so focused on caring for the cub—even stimulating the cub to relieve itself—that she will not have time to find her own food and will probably refuse the food that the zoo keepers offer to her.

“All they do is raise this cub, they don’t think about themselves,” says Laurie Thompson, a giant panda biologist at the National Zoo said Friday. “And this is an animal that can crush bamboo very easily, but they carry them very gently in their mouths.” After the first week or so she will make attempts at putting the cub on the ground so she can get up for food, but she will quickly return to the helpless cub which, as usual, was born blind and deaf.

The cub will probably not start leaving the den until it is about four months old. Around that time, visitors to the Zoo may get their first glimpses of the cub at the indoor panda enclosure. But it is more likely that zoo-goers will have to wait until the cub is about five or six months to see it romp around the outside enclosure. Once out there, the cub will play with her mother and attempt to climb trees.

When the cub is around 18 months, Zoo keepers will separate it from Mei Xiang, as this is the age at which it would leave its mother in the wild. If not separated, Mei could become aggressive toward the cub and because she is unable to conceive as long as she is nursing it is necessary to separate them so she can prepare for another attempt to become pregnant. But if her previous cub, Bao Bao, is any indication, the cub will not suffer too much separation anxiety. According to Thompson, Bao Bao’s main concern is the location of her keepers.

And just like Tai Shan in 2009 and Bao Bao in two years, this cub will be sent to China when it is four years old to live out the rest of its adult life.

Fingers crossed for a healthy birth and since the panda cam is overwhelmed, we offer this slideshow of images of Mei Xiang and her other cubs to satisfy your panda cub longing.