Ai Hin, a 6 year old panda at the Chengdu Giant Panda Breeding Research Center, the same place some of our San Diego pandas now call home, is said to have faked a pregnancy to get special treatment, including more food, air conditioning and increased attention. Chengdu reported Ai Hin was showing signs of pregnancy in the form of reduced appetite, less mobility and a surge of progestational hormone. But, it could be possible she was pregnant but reabsorbed the fetus. Surges in hormones are hard to fake and it is fairly common for pandas to lose a pregnancy, reabsorbing the fetus so it appears as if there was no pregnancy at all. Reabsorption could happen because there is a fetal defect or death, the mother has a disease which affects her ability to properly care of the fetus, there is a hormonal disruption, or environmental conditions are not conducive to caring for the baby. At the San Diego Zoo, they have seen this phenomenon with the use of thermal imaging and ultra sound. Bai Yun was suspected to be carrying twins on more than one occasion but has only ever given birth to one cub. This kind of fetal reabsorption is called "prenatal litter pruning". The mechanism isn't exactly known but could be an adaptive result of pandas not being able to care for more than one cub in natural, wild conditions.
Who knows. Maybe Panda McLiar Pants wasn't lying after all but her body decided this just wasn't the time. She's only 6 and has never been a mother. Maybe she just wasn't ready yet!!