Sleeping Positions During Pregnancy

During pregnancy, a woman's body goes through a plethora of changes. An ever-expanding abdomen, back pain, heartburn, insomnia, and shortness of breath can make getting enough rest a real challenge.

Dr. DiLeo answers questions about which sleeping positions are best, which to avoid, and how to get as comfortable as possible while trying to catch some much-needed rest.

Is it really healthiest to sleep on my left side and not my back? Why?

Sleeping on the left side is best for you and the baby—and it's all a matter of anatomy.

As the baby grows, the abdomen has to harbor an ever-increasing uterus. The heavier uterus rests flat on the inferior vena cava—the main vein just on the right side of your spine that drains the entire lower half of the body.

When the vena cava is compressed, much like stepping on a garden hose, flow towards the heart is obstructed and drainage of the lower half of the body becomes sluggish. Not only does this increase the swelling of your ankles, feet, and legs, but it also impacts hemorrhoids (ouch!). And decreased return of blood flow to the heart will cause hypotension (lowered blood pressure) down the line and result in diminished arterial blood flow to the uterus, placenta, and baby.

Sometimes this hypotension is evident when a woman has an ultrasound, during which she lies flat. One of the symptoms of hypotension is nausea that accompanies light-headedness.

All of this makes lying on the back the worst possible sleeping position in the third trimester of pregnancy. Lying on the right side is better than lying on your back, but lying on your left side is the best of all, because this is the position which will have the least amount of weight upon the vena cava.