Long pregnancy?

[Mathias Gabel]

Hi!

I have one female gerbil, who is pregnant since March 1st---at least I think
she is. I might be wrong, of course, but I'm relatively sure that I'm not.
What can be the reason for such a long pregnancy? Or could it be a disease?
She is doing fine, eating well and shows no abnormal signs, except that she
stays a lot of her time in the nest. But I think that would be normal if
she's pregnant.