Question: how many weeks pregnant do you have to stop sleeping on your back?
Answer: You may want to get used to a new sleep position now, since you shouldn't sleep on your back after 20 weeks of pregnancy. When you lie belly-up, the weight of your uterus can compress a major blood vessel, called the vena cava. This disrupts blood flow to your baby and leaves you nauseated, dizzy, and short of breath.