PREGNANCY & COMPRESSION SUPPORT HOSIERY.
Pregnancy is a special time to take care of your developing baby and yourself. While much of the focus is on your baby and bodily changes, changes are also affecting your veins. The normal hormonal changes that occur with pregnancy affect the walls of your veins causing the vein walls to relax or dilate. Relaxation of the veins occurs early in the pregnancy – during the first trimester. Total blood volume also increases in the first trimester and gradually rises with gestation. Your total blood volume may increase as much as 45% in comparison to the non-pregnant level. Relaxation of the vein walls, especially in areas of venous valves may cause the valve to become incompetent – thus allowing backward flow of the venous blood. Vein relaxation, valve incompetence, and increased blood volume all contribute to reducing venous flow from your legs. The reduced flow results in congestion. Venous congestion in turn causes swelling and leg discomfort. Ankle swelling occurs with most pregnant women.
During the later months of pregnancy (third trimester) the weight of the baby and the uterus may impede return of blood through the veins of your legs. This is often dependent on your physical position.
Gradient compression stockings reduce venous congestion and support the superficial veins of your legs. This helps manage the increased blood volume and relaxed vein walls thus reducing the amount of swelling and the severity of varicose veins.
Talk with your obstetrician or OB nurse about the amount of compression and stocking style best suited for you during this pregnancy.
VEINS & VALVES
Most of our blood volume is carried in the veins (64%). Veins can expand to hold large amounts of blood. Veins are blood vessels that carry blood from the body back to the heart. Blood return from the legs occurs mainly through the deep veins. Within the veins, especially those of the legs are valves. Venous valves are bicuspid (two) flap like structures made of elastic tissue. The valves function to keep blood moving in one direction.
The flow of blood in the venous system is complex for several reasons: the low pressure within the veins, flow rates that vary from high (during muscle contraction) to almost no flow during quiet standing or sitting positions, the effects of gravity, the collapsible nature of the venous wall, the presence of valves, and the large volume of blood carried in the veins.
Once
the blood has passed from the arteries through the capillaries, it is flowing at
a slower rate because little pressure remains to move the blood along. Blood
flow in the veins below the heart is helped back up to the heart by the muscle
pump. The walls of the veins are thin and somewhat floppy. To compensate for
this many veins are located in the muscles. Movement of the leg squeezes the
veins, which pushes the blood toward the heart. When the muscles contract the
blood within the veins is squeezed up the vein and the valves open. When the
muscle is at rest, the valves close helping to prevent the backward flow of
blood. This is referred to as the muscle pump.
