Sleeping positions - can I sleep in my back?

Harpo

So I’ve read that when you get to the second trimester you aren’t supposed to sleep on your back. I’m 19 weeks and love sleeping on my back. I’m wondering if what I’ve read is just advice or if it’s a big no no? I sleep on my sides too but I like to move around and find it comfy on my back still. When I get further along and bigger I’m guessing I won’t find it comfy anymore.