If you believe the internet, there is no healthy way for you to sleep: front, back, side, fetal; they are all going to cause you problems like acid reflux, spinal problems, skin problems, problems with your breasts.
Here is a sample of the claims and I have found a couple of sources for sleeping on your back being a problem unless you add a rolled up towel or pillows under your legs.
Is there a sleep position which will give you less (or none at all) medical problems when compared to others?
Unless there are medical concerns is it possible to sleep without assistance (extra pillows, towels, whatever) without risking or causing issues with your health?