Sleeping on the left side improves circulation to the heart and allows for the best blood flow to the fetus, uterus, and kidneys. However, during pregnancy, you can also sleep on your right side for short periods of time.
Sleeping on your back puts extra pressure on the blood vessels that run behind your abdomen and carry blood back to your heart from your legs and feet. Pressure on these vessels can slow blood circulation to your body and your baby.




