Sleeping on your back??

Lacey • I am 33. Married for Eight years. I am a dental hygienist. My husband works in industrial mechanics. We have a 2 year old little girl and are trying for baby #2
How serious of a problem is it to Sleep on your back when pregnant. I'm 19w6d and always fall asleep on my left side but wake up on my back even with Pillows behind my back.