Laying on your back!!

Ty

So I see so many post/articles about how it's very unsafe for mothers to lay on their back while pregnant. But what I want to know is there any mom's out there who have experienced the reason why we shouldn't? I sleep like a log on my back it's so relaxing and my hips get a break. Or is there a safe way to lay on your back? I just need answers because nothing works, body pillows only help so much. I just really want to sleep on my back lol...but if I can get some real life experiences on why they find laying on your back is so unsafe I want to hear it.