The National Zoo in Washington D.C. announced today that Mei Xiang, a 19-year-old panda isn’t pregnant after all. It was just a “pseudo pregnancy,” or fake pregnancy. Seems she had all the signs (nesting, eating less) and even hormonal changes. But the one thing she didn’t have was a fetus in her womb.
So, what was going on with her hormones? In short, some animals after sex or artificial insemination, have a rise in certain pregnancy hormones can rise for a few weeks. Then without a fetus gestating, the levels eventually go back to the non-pregnant state. That seems to have been Mei Xiang’s story. She had a progesterone surge but an ultrasound didn’t find a fetus
In an article aptly called, “Pseudopregnancy in the Bitch,” and published in the Journal of Small Animal Practice in 1986, the authors explain that the condition has to do with the way post-coital hormones are released from the pituitary gland, a gland that dangles off the brain. It’s not uncommon in mammals that go through estrus, which is different from humans that menstruate. (Estrus means that the lining of the womb is absorbed back into the body after the egg is released but there is no conception. For many species, the females are only sexually active during estrus. Humans menstruate—that means they bleed and sometimes have sex when they aren’t fertile.) In humans (but not pandas) “pseudopregnancy” also called pseudocyesis and is listed in the DSM-5, the psychiatrists bible of mental disorders.
At 20, the Mei Xiang is considered on the older end for giving birth, but the National Zoo veterinarians aren’t giving up hope yet.
For further reading on pregnancy hormones and a pioneering researcher, check out Chapter Six in my latest book: Aroused: The History of Hormones and How They Control Just About Everything