A female panda is estrual only once a year, and also only mates once a year. Panda’s estrous cycle lasts between March to April every year.
But their pregnancy period varies as individuals. The shortest pregnancy period observed so far is 83 days; the longest is 181 days.
An artificially reared giant panda is fertile from 1 year old. The variety in pregnancy period can even be controlled by the panda itself against external stimulation.
Pandas often give birth during autumn. A newly-born panda weighs about 100 grams. It is smooth and hairless, therefore vulnerable and has a low survival rate.