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).
But sleepless nights plague women throughout pregnancy, too. A National Sleep Foundation poll found that over three-quarters of women slept worse during pregnancy than they did when they weren't pregnant. What's more, new moms and pregnant women were more likely to suffer insomnia than any other group of women.