It's not a fast pass. Get a note from your ob and take it to guest services. You get a pass that your whole party can use. You go to the fast pass line at each attraction and show the cast member.
Sorry but unless a true disability exists one should NOT be getting a GAC for being pregnant. Pregnancy is NOT a disability!!!!! We did see a woman in June riding in an ECV while very pregnant and using the accessible entrance for a ride. There were a lot of looks that way and there were a couple of other pregnant women standing in line waiting. I had to wonder their thoughts.