Tian Tian, a giant panda living in a Scottish zoo, might be pregnant. The baby would be the first panda born in the U.K.

Nesting behavior and changes in hormone levels suggest Tian Tian is either expecting or having a phantom pregnancy, the BBC reported.

Tian Tian and her hubby are the only two giant pandas in the U.K.

The Edinburgh Zoo is renting the pair from the Chinese government for 10 years, the zoo is paying about $930,500 for the visit.

Tian Tian has not let trainers perform and ultrasound, so they will have to wait and see if she gives birth within the month.

The panda pair has tried to mate twice before, but both times proved to be unsuccessful.

Tian Tian was artificially inseminated on April 21. Since two different males were used in the insemination, Tian Tian could have "twins by two different fathers."

"It's hugely exciting. There's never been a baby panda born in the UK," Mr Valentine, director of the zoo's giant panda program, said.

Urine samples helped determine the procedure may have been successful.

"The hormone concentrations we measured in the urine sample from the panda increased," Dr Martin Dehnhard at the Leibniz Institute, said. "That tells me that she is pregnant or pseudo-pregnant."

Phantom pregnancies are fairly common in pandas, but the program is trying out  a new test in hopes of ruling out that scenario. 

The test, which was developed in a Memphis zoo, will test Tian Tian's protein levels to determine if she is actually pregnant and if the cub will be carried to term.

Tian Tian's test suggested she will have a successful pregnancy, but the technique is new and its efficiently has not been well-tested.

If the cubs are born, they will be China's property. The babies will return to their country of origin with their mother in several years.

Zoo staff are hopeful the giant panda is expecting.

"Results so far are very encouraging," Chris West, chief executive of the Royal Zoological Society of Scotland, the charity that runs Edinburgh Zoo, said.