How to access previous updated_at?

I have model in which I keep track of the field updated_at.

Is there a way I can track the previous updated_at?

For example

updated_at = A (where A is an actual datetime stamp)

Some work is done then save is called

updated_at = B (where B is an actual datetime stamp)

Is there a way I can access the previous updated_at i.e. A?