If I remember correctly, a pregnant cat can and should be dewormed, but she should NOT be vaccinated while pregnant. Please contact your vet to confirm this information and find out which dewormer to use.
you can worm her, Milbemax is a good wormer and easy to give being a small tablet. Wormers are all over the counter here, some countries require a vet prescription for tablets so you might need to take her in
I did a Google search on this last night, and I found several different recommendations from veterinarians. One said that the queen should be dewormed during the first two weeks of pregnancy, but not later than that. Several others said to wait until after the queen has had the kits to deworm her. So, I recommend you wait until after she has the kits ... unless your own vet recommends deworming her sooner than that.