The National Zoo says panda mother Mei Xiang (may-SHONG) is showing a spike in hormone levels, a sign that she might be pregnant again.

But there's no reliable pregnancy test for pandas, and this could be a false alarm.

Mei Xiang was artificially inseminated in March with semen from Tian Tian (tee-YEN tee-YEN), the zoo's male giant panda. Test results Thursday indicate Mei Xiang will either give birth or come to the end of a false pregnancy in mid- to late-July.

Mei Xiang gave birth to her first cub, Tai Shan (ty-SHAWN), in July 2005, helping to boost zoo attendance and create numerous new panda fans.

Scientists tried to artificially inseminate Mei Xiang last April with semen taken from Gao Gao (gow-gow), a giant panda at the San Diego Zoo. But they later determined she was not pregnant.