Pregnant Cat Scooting?

Has anyone ever experienced a cat rubbing their bottom on the floor (scooting) before delivering? My Cleo just did this, and I have NEVER EVER seen her do it before. Now it's got me paranoid that she's not pregnant and just has worms lol.

Today she has been wandering aroudn the house only to stop to eat, use litterbox and lick her bottom. She is sooo large she looks like she's going to pop!

Have you felt kittens move? a vet checked her? It could be that she just can not reach back there to well so doing the best she can lol, it also could be worms, if your worried speak to your vet, we can only advise. hope everything goes ok .

I would not be guessing about this...
Your vet should have a look asap.