How many months does a tortoise stay pregnant?

It depends to a great extent upon the temperature at which the eggs are incubated. In the temperature range suggested, between 8-11 weeks is about average for most species. The lower the temperature the longer it takes. At around 27C for example, incubation can take 18 weeks or more. At temperatures above 34C however there is a grave risk of mortality or deformity among the hatchlings. It is best to incubate at the medium range temperatures suggested.