(REUTERS) - Is she or isn't she?
Mei Xiang, the darling giant panda of the National Zoo in Washington, DC, may be pregnant again, although zoo officials say it's too early to tell.
"We're hopeful, but we cannot tell, because pandas have false pregnancies, so you really never know until you actually see a cub being born whether they're pregnant," said biologist Laurie Thompson.
Mei Xiang was artificially inseminated in April this year, and is showing behaviours of an expecting panda mother, such as building a nest in her den and taking extra long naps.
The only way to know for sure is to take an ultra-sound but that can be difficult as panda fetuses do not develop until the final stages of gestation and female pandas are often not cooperative in the process.
If Mei Xiang were to give birth, it will join sibling Bao Bao born at the zoo in 2013.