Officials say the hormone levels of the Washington's National Zoo's adult female panda are rising, but they don't know whether she is pregnant.
The Smithsonian announced Monday that the hormone levels of panda Mei Xiang began a secondary rise July 20. Officials say that means that within 30 to 50 days, she will have a cub or experience the end of a "pseudo-pregnancy."
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Mei Xiang had five pseudo-pregnancies between 2007 and 2012.
Zoo officials have said panda pregnancies can be difficult to detect because a female panda's hormones and behavior are the same whether she's pregnant or not.
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Mei Xiang was artificially inseminated in the spring. If she's pregnant, it would be her third cub. One of her cubs, Bao Bao, is a popular resident at the National Zoo.
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