I don't know about being pregnant but can tell you my neighbors probably share the same concern. I am always looking at their rear ends as I have due any second that are making me crazy. I would love to master the skills to tell by looking at a pooch to tell if they are pregnant or not
I can't see what they are talking about yet, but I understand that there is a change in tone as well as a change in location with relationship to the tailhead. I have read from a thread Goathiker responded to, that as she gets closer to delivery the anus begins to "smile" as opposed to "scowling" .