Giant panda Mei Xiang's hormones are on the rise

Scientists at the Smithsonian have confirmed a slow rise in giant panda Mei Xiang's urinary progesterone levels that started July 20, which indicates that she will either have a cub or experience the end of a pseudo-pregnancy within the next 30 to 50 days.

It is not clear if Mei Xiang is pregnant because a giant panda's behavior and hormones can mimic a pregnancy even if she is not pregnant.

Mei Xiang was artificially inseminated April 26 and 27 using frozen sperm collected from Hui Hui, a panda living in China, and fresh sperm collected from Tian Tian, who lives at the National Zoo.

The zoo's panda team is monitoring changes in Mei Xiang's reproductive tract and evaluating for evidence of a fetus, but officials said it may still be too early to detect a fetus on an ultrasound.

Scientists are also continuing to monitor her hormone levels on a daily basis.

Meanwhile, Mei Xiang is exhibiting behaviors consistent with a rise in urinary progesterone, such as nest building, choosing to spend more time in her den, sleeping more and eating less.

Mei Xiang has given birth to two surviving cubs, Bao Bao and Tai Shan.