Not pregnancy specific but if you have decent baseline fitness barre classes are usually pregnancy friendly and a really good workout. I did them until 30 weeks.
19 weeks here and I have been going to good times Pilates and find their classes quite nice (plus I like that they are 45min) ☺️
I used class pass and went to a couple of different studios/gyms that were happy to train pregnant people, were not pregancy specific classes. I just double checked with the places before booking the class, and stuck with the couple i found i liked and knew they could help me exercise safely during my pregnacy. They just accomadated/swapped out exercises if needed (I didn't do any exercises on my back from 12 weeks except bridge's and no crunches/sit ups either.) Was doing strength classes until 37 weeks and reformer pilates right until the end at 40 weeks (went to a class day before labour 😊) I highly recommend doing pilates and strength, and regular long walks (If your able too). I live St kilda way so can't help with where to go but cannot recomrnd enough staying as active as possible during pregnacy 😄💪
I attended both Core Plus in Ivanhoe (their warm yoga classes, not hot) and also Fort Green Yoga studio slow flow yoga classes in Northcote. Both felt like a good workout and I was doing them from early pregnancy until the day before I gave birth and just adjusted as I went along. Although it’s “slow” that just means you’re holding poses longer (thigh burn!), I did attend the prenatal yoga at Fort Green much later in my pregnancy and totally understand what you mean about it not being a big workout.