Concerns over pregnant gerbie

[Tony P]

Heya guys,   I'm getting slightly concerned about my gerbil female...  today is the 27th day since she mated, and there are still no pups.   The vet was pretty confident that she was pregnant and that was about a week ago now.  She seems to go from being quite podgey to being fairly thin (sparking hope as it makes myself and my partner think shes had them) but no luck yet.   The male has been sleeping on his own on the top shelf of the cage for the last week or so, so I'm confident that she is pregnant as well.   I'm planning on taking her to the vet on Monday (29th day) if she hasn't had them by then, but I was wondering if there's anything I can do to encourage or speed things up a little?   Thanks :)   Tony P