Urine tests on Mei Xiang have revealed a hormone spike that could mean she is expecting, The Washington Post said Friday.

Mei Xiang was artificially inseminated this spring with semen from the zoo's male panda, Tian Tian, a procedure that produced the cub Tai Shan in 2005.

But zookeepers aren't passing out cigars just yet. Pandas are notorious for "pseudopregnancies," and Mei Xiang has had four of them since 2005.

It will likely be mid-July before a genuine pregnancy can be cofirmed, zoo officials said.