Ai Hin, a giant panda, was all set to give birth. She even had a live broadcast set up by her caretakers to help mark the event. The only problem was, she was not really pregnant.

The great panda had been showing signs of pregnancy for two months. She was less energetic and her appetite decreased, just as other pandas behave when they become pregnant. She was given the comforts often afforded pandas in captivity who conceive, including air conditioning, tasty treats like bamboo, fruit and buns, and constant care to support her through the gestation period. In the end, it was discovered that she had experienced a “pseudo pregnancy.”

Some feel that the extra amenities given to pandas encourages them to continue acting pregnant despite the fact that they are not. Other evidence indicates that the issue might not be as clear cut as that.

Reproductive systems in pandas are more complicated than in many other animals. Females only ovulate once a year and when ovulation occurs, they only have one to three days to become impregnated. Hormone tests to establish pregnancy are essentially useless in giant pandas as their hormones react to ovulation and not fertilization of the eggs. It is often not even possible to confirm a pregnancy using an ultrasound because panda fetuses are very small.

Researchers believe that the experience of a “pseudo pregnancy” could also be the result of a miscarriage. The loss of pregnancy in pandas is believed to be a common occurrence.

Another theory stems from the observed phenomena of pseudo pregnancies in pandas who have not had a chance to breed. It is possible, given the restrictive nature of their reproductive systems, their lifespan of about two decades and the length of time each cub needs to be cared for, that a reaction similar to pregnancy could occur as a means of preparing the body to avoid lost opportunities.

A giant panda really only has enough time to produce about six cubs in its lifetime.