how long is too long to lay on back?

🌙🔮
So every month I get a Brazilian wax which requires that I lay on my back, the place that does it makes little accommodations since I'm pregnant like propping the table up a teeny tiny bit so I'm not completely flat on my back but it's still pretty much on my back. So I know it's dangerous to sleep on your back while pregnant but how long is too long? And do you think that continuing to get waxed with this considered is still safe and ok to do?