July 13, 2011
A little knowledge is dangerous; especially when it relates to medicine. A recent article in the British newspaper, Daily Mirror discussed a medical study that attempted to prove there was a link between pregnant women’s sleeping positions and stillbirth. The author is of the opinion that the study was small and biased and therefore “there is a serious need for more research before we’re in a strong position to make ¬any recommendations.” Obviously this author has limited knowledge about the cardiovascular system of a pregnant woman.
Our organs and tissues require oxygen to function. Without it, they essentially die. Blood from the lower part of our body flows back to the heart where it receives oxygen, compliments of a large blood vessel called the Inferior Vena Cava (IVC). The inferior vena cava is a large, thin-walled blood vessel located near the spine. As the pregnant uterus becomes enlarged, it can press against the IVC and reduce the amount of its blood flow. Why is that not good? Because it reduces the circulating blood flow in the body that is commonly known as our cardiac output (CO). When the pregnant uterus squeezes the IVC and reduces cardiac output, a woman might feel dizzy and even faint. Her blood supply of oxygen is reduced and the unborn baby’s is as well. When a pregnant woman in her early or late third trimester feels faint after lying flat on her back, the syndrome is called Supine Hypotensive Disorder. Her blood pressure has dropped because her cardiac output has dropped. The heart can only pump out what comes into it, so less blood into the heart means less blood going out of the heart and the patient feels faint. How is this avoided? By encouraging pregnant women in their third trimester to sleep on their left side.
What happens when a pregnant woman sleeps on her left side? The uterus is no longer compressing the thin-walled IVC but lies against the thick-walled aorta instead. The aorta brings oxygenated blood away from the heart and to essential organs and tissues. Because of its thickness it’s not affected by the weight of the pregnant uterus. What if you can’t sleep on your left side? Then sleep on your right side but avoid sleeping flat on your back.
Although medical studies have allegedly not proven that sleeping on the left side reduces stillbirths, it is still sound advice to avoid maternal and fetal complications. Remember, a healthy pregnancy doesn’t just happen — it takes a smart mother who knows what to do.