Cat sensing pregnancy?

Ok so I’m 30 weeks pregnant and have 2 cats. One of which I’ve had since she was 6 weeks old and she usually follows me everywhere like a shadow, lays all over me, sleeps at the end of my bed and just very affectionate but in the last week she’s been really anxious and stressed. She’s been sleeping under the bedside table in the spare room for a few days now and just doesn’t want to come out. She’s doing this twitchy thing when I do try and touch her and is overly cleaning wherever I’ve patted her. She’s now scratched me a couple of times in the last two days and hissed at my partner. I’ve got a vet appointment today to rule out any underlying illness but I’m just wondering if anyone else has experienced this?