WASHINGTON (AP) -- The National Zoo says that its female giant panda Mei Xiang is not pregnant and officials have ended their round-the-clock pregnancy watch.
Zoo veterinarians announced Friday that Mei Xian was experiencing a "pseudopregnancy" over the past several months. They had been keeping a close eye on her behavior and monitoring her hormone levels.
It's difficult to determine when a panda is pregnant. Scientists say panda fetuses don't start developing until the final weeks of a gestation period.
Mei Xiang stopped allowing animal keepers to perform ultrasound exams on her in early July.
The zoo was hopeful, though, because a Chinese panda breeding expert helped zoo scientists artificially inseminate Mei Xiang in January. She and male panda Tian Tian had attempted to mate but failed.