Features

• During pregnancy, blood volume increases by approximately 50 percent. If the vascular system remained as it normally is, the increased volume of blood would cause dangerously high blood pressure. Fortunately, the body is able to compensate through vascular changes. During pregnancy, existing blood vessels become larger and stretchier to accommodate the increase in blood. Networks of new blood also appear throughout the body. Because blood vessels become softer and stretchier, and are often "overfilled," it is not uncommon for blood to leak into surrounding tissues.
  
  

Function

• The increased production of blood serves a clear purpose: supporting the growth of the fetus. Much of this is achieved through the placenta, an organ present only during pregnancy. The placenta is a very vascular organ; it is filled with an immense network of blood vessels. The uterus also grows much larger during pregnancy; it expands from the size of a small pear to the size of a soccer ball, and must develop powerful muscles to expel the baby during labor. Increased blood volume also helps prevent serious complications as a result of giving birth. A woman whose blood volume did not increase during pregnancy would almost certainly go into shock from the blood lost during delivery.
  
  

Effects

• Unfortunately, the vascular changes of pregnancy cause many unpleasant side effects. Because veins become stretchy and soft, they often become distended. This causes varicose veins, especially in the lower legs, vulva and rectum. Varicose veins in the rectum are particularly common, and are commonly known as hemorrhoids. Increased vascularity in the gums often leads to bleeding when a pregnant woman brushes her teeth. Leakage of small amounts of blood into the surrounding tissues causes local swelling, or edema. Edema of the ankles, eyelids, hands and face are commonly experienced during pregnancy. The enlarged blood vessels can decrease blood pressure in some women, which makes fainting and dizziness common during pregnancy.
  
  

Treatment

• Treatments for the unpleasant side effects of vascular changes during pregnancy consist of comfort measures. The discomfort of varicose veins can be partially relieved by elevating legs and wearing supportive pantyhose. Hemorrhoids often respond well to over-the-counter creams and warm baths. Using a soft toothbrush can help reduce bleeding of the gums. Fainting and dizziness can be decreased by standing up slowly and avoiding standing in one position for long periods of time.
  
  

Significance

• Most vascular changes that occur as a result of pregnancy reverse within a few months after delivery. However, some women develop permanent varicose veins or hemorrhoids. Bleeding from the gums and edema usually go away within days after childbirth. Migraine headaches during pregnancy, which are a result of rapid expansion of blood vessels surrounding the brain, have been associated with an increased risk of serious health problems. According to one study, women who experienced migraine headaches during pregnancy were 19 times more likely to have a stroke, and almost 5 times more likely to have a heart attack.