The most dangerous drug in the world: 'Devil's Breath' chemical from Colombia can block free will, wipe memory and even kill. 1  Scopolamine often blown into faces of victims or added to drinks.
To summarize, it appears the best position is left side, followed by right side. After 16 weeks it's best not to sleep on your back, and you probably won't sleep on your stomach. (One way to avoid sleeping on your back is to sew a tennis ball into the back of your pajamas; this works for people who snore, too).
3 doctors weighed in: When during pregnancy should you stop laying on your back? 3 doctors weighed in Want a second opinion? At approximately 24 weeks you should avoid laying on your back for prolonged periods of time in order to avoid compression of veins (vena cava). In brief: 6 months.