Giant panda fans who have been eagerly awaiting the possibility of another panda cub at the Smithsonian's National Zoo received an update Thursday: female giant panda Mei Xiang's hormones are rising.

The zoo said in a blog post that Mei Xiang's hormone levels have been increasing over the past few weeks although they have not yet reached a level typically seen during ovulation.

"The hormonal changes are a good indication that Mei Xiang may be coming into estrus," the zoo wrote. "However, it is still too early to say for sure whether or not she will ovulate."

The zoo said if Mei Xiang does ovulate, artificial insemination will be attempted the same day and the day following.

Mei Xiang is 23 years old and has had three cubs: Tai Shan in 2005, Bao Bao in 2013 and Bei Bei in 2015. Her oldest cub, Tai Shan, now lives in China.