I used a chiropractor. My OB ok'd it. Chiropractor had a lot of experience working with pregnant women. He was excellent and helped relieve by sciatica.

Do you get naked, or just wear comfortable and loose clothing?

For your first visit they will talk to you, explain everything before they do it, ask if you have questions, where your pain is, etc. Mine had pregnancy foam pillow things so I could still lay on my stomach, but for the hip adjustments it was on my back bent a bit to the side (and worked WONDERS). I also carry tension in my neck and had that done as well, which was amazing. I'd rather go to the chiro than a massage therapist