Zookeepers at the National Zoo in Washington artificially inseminated its female giant panda, Mei Xiang, in April after efforts to get her to mate failed.
And now officials suspect she might be pregnant.
The 13-year-old panda’s hormone levels are up, she is acting ‘spaced out’, and she has begun nesting.
Panda keeper Juan Rodriguez told the Smithsonian.com that Mei has been shredding bamboo and collecting it in a corner of her den since the beginning of August.
But Mei has displayed similar behaviour in the past during what experts have described as ‘pseudopregnancies’.
The panda has had five ‘fake’ pregnancies in a row so officials do not want to get their hopes up.
‘That’s the thing with pseudopregnancies and real pregnancies, there’s really no difference,’ Rodriguez told the website. ‘We try to stay subdued over here.’
An ultrasound won’t reveal a definitive answer until two weeks before the birth but the team has still been testing her and conducting weekly urine samples.
‘If she gives birth we’re ready to rock, but we also don’t want to get our hopes up too high,’ Rodriguez added.
Mei and male panda Tian Tian, 14, were previously put in the zoo’s panda compound but failed to mate naturally, as has been the case on numerous other occasions.
So veterinarians played mother nature and took the situation into their own hands with an artificial insemination.
It is the eighth year they have tried to artificially impregnate the panda and the fluffy couple have one son through artificial insemination, Tai Shan, born in 2005.
There is just a 10 per cent chance it has worked but having tried on two days in April, zookeepers are hoping for a birth within 40 to 50 days.
Staff took to Twitter to broadcast the insemination in April after Mei went into heat.
‘We always want to try to give updates to the public as much as we can,’ Renick-Mayer told the Washington Examiner. ‘We figured Twitter would be a great platform for that.’
While eager panda fans tracked their progress using the hastag #pandaAl, Li Desheng, of the China Conservation and Research Centre for the Giant Panda in Wolong, and vets from the zoo carried out the insemination.
They used thawed ‘vintage’ sperm from Tian Tian, collected in 2005. Staff will monitor Mei’s hormone levels and perform ultrasounds in the coming months to determine whether she is pregnant.
The National Zoo tweeted a photo of a weary-looking Mei with the words ‘here’s our slightly groggy, black-and-white rock star in recovery’.
Before beginning the insemination, zoo staff excitedly tweeted: ‘It only takes one!’ Afterwards they wrote: ‘This is a big moment for us! If what happened in the last few minutes takes, we could have a panda cub here this summer!’
They added: ‘Mei did great and there’s a sense of celebration and accomplishment in the air here!’
Read more: MailOnline