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Here is our dutiful post informing you that a panda might once again be pregnant at the National Zoo.

Zoo scientists confirmed this morning that its lady giant panda, Mei Xiang, has demonstrated a secondary rise in urinary progesterone. Mei Xiang will either give birth to a cub in 40 to 55 days or end this pseudopregnancy. Veterinarians are regularly monitoring the bear with ultrasounds, though it’s quite difficult to determine if a panda is actually pregnant because a giant panda fetus doesn’t start to develop until the final weeks of gestation.

As anyone who has followed the extensive past local coverage of this topic, our zoo’s pandas haven’t quite mastered the facts of life. Mei Xiang once again had to be artificially inseminated twice this spring after she and her male counterpart, Tian Tian, failed to procreate naturally. Mei Xiang has given birth to two cubs: Tai Shan, who returned to China, in 2005; and an unnamed girl cub who died after one week last September.

This time around, scientists used sperm from both Tian Tian and San Diego Zoo panda Gao Gao (pictured). We’ll see if this West Coast flavor can boost Mei Xiang’s chances of delivering a baby cub.

Photo courtesy of the National Zoo