The National Zoo said Friday that its female giant panda, Mei Xiang, appears to be pregnant, and the birth of a cub — amid the nation’s medical, social and political upheaval — could come as early as this weekend.

The zoo said it launched its 24-hour-a-day panda cam watch Friday.

An ultrasound Friday morning clearly showed what looked like a fetus, the zoo said. Chief veterinarian Don Neiffer said there could even be two.

“I can’t confirm or deny that there’s two there,” he said. But “I would expect that she may have two, because that’s what [pandas] do and that’s what she’s done in the past.”

“So that’s what we’re all planning for,” he said. “I suspect there are two.”

Mei has had twins twice before. In both cases only one cub survived, which is not unusual, he said.

The panda could also have a stillbirth, or the fetuses could be resorbed, said spokeswoman Pamela Baker-Masson. But zoo officials were extremely hopeful.

“We are totally surprised,” she said. “Reproductively speaking, this is like a miracle.”

The zoo has not had a giant panda cub in five years — since its departed male Bei Bei was born in 2015. (He was moved to China last year.)

Mei is 22 and near the end of her reproductive life, the zoo has said. “She’s aged,” Neiffer said. Because she hadn’t gotten pregnant in the past few years, he and others thought she might be too old.

“She’s definitely at the end game of reproductive success,” he said. “So this is awesome.”

“This is like that Hail Mary football pass,” he said. “If there was ever a time that Mei Xiang needed to do us a [favor] and have a baby, it’s right now.”

If she gives birth, she would be the oldest giant panda in the United States to do so, Baker-Masson said.

“In the middle of a pandemic, this is a joyful moment we can all get excited about,” said Neiffer, who conducted the ultrasound.

“We are optimistic that very shortly she may give birth to a healthy cub,” he said in a statement. “We’re watching [Mei] closely and welcome everyone to watch with us on the panda cams.”

In an interview, Neiffer said some clues started emerging on ultrasounds about 10 days ago. Images showed “tissue growing that was not the uterus,” he said.

On Friday, he was able to get “10- to 20-second video clips of her abdomen,” he said. “Immediately, the structures that we saw last week were much bigger, and I was convinced that we were looking at a fetus.”

Neiffer said he was unable to see the heart, but there was “nothing that indicates that we have a fetus that’s in distress. . . . It’s all going the way it should, for now.”

“I’m hedging my bets that we’re going to see something within the next four days, maybe sooner,” he said. “I’m optimistic that she’s going to produce babies. Whether or not they’ll be alive . . . we’ll have to wait and see.”

Neiffer said he did not think the quiet during the zoo’s shutdown had anything to do with the pregnancy. He noted that Mei has gotten pregnant in the past when the zoo was open and going “full tilt.”

“So I don’t believe that’s the case,” he said.

He said the zoo’s panda pregnancy team would meet and make sure everyone was ready. “It takes a village to raise a panda — or at least get one out,” he said.

Mei was artificially inseminated on March 22 with frozen semen that had been collected from male giant panda Tian Tian.

Mei has had numerous “false pregnancies,” which are common in giant pandas and happen when the animal exhibits early signs of pregnancy but no cub appears.

That is not the case this time, the zoo said.

Mei Xiang has given birth to three surviving cubs: Tai Shan, Bao Bao and Bei Bei.

Tai Shan was born in July 2005 and now lives in China. Bao Bao was born in August 2013 and moved to China in February 2017.

By agreement, all cubs born at the zoo are sent to China when they are 4 years old.