Pregnancy & Cardiovascular ChangesWomen's cardiovascular systems in particular need to be resilient. As compared to a man's, a woman's body goes through extraordinary changes during her lifetime. These changes can have an enormous effect on her cardiovascular system. The most dramatic example of this is pregnancy.
These changes in the cardiovascular system develop primarily to meet the increased metabolic demands of the mother and fetus. Special demands are made upon the maternal heart, so a woman with a history of heart disease, heart murmur, hypertension, or rheumatic fever should talk with her doctor before she decides to become pregnant. A woman with congenital heart disease has a higher risk of having a baby with a heart defect and may need to have diagnostic tests performed.
Changes that occur, or may occur, during pregnancy include:
- Anemia. During pregnancy, blood volume increases by 40-50% but the number of red blood cells increases by only 20-30%, causing what's known as the anemia of pregnancy. This is not considered abnormal unless red blood cell levels fall too low.
- Varicose veins. Varicose veins may develop during pregnancy for a number of reasons. The additional volume of blood places additional pressure on the veins. As the uterus enlarges during pregnancy, it puts pressure on the inferior vena cava, the large vein on the right side of your body. This in turn increases pressure in the leg veins. In addition, during pregnancy progesterone levels rise, causing veins to relax. This may allow the two halves of the valves in the vein to separate slightly so that there is some backflow of blood into the vein, a condition termed venous insufficiency. Varicose veins generally appear on the legs, but during pregnancy varicose veins called hemorrhoids may also arise in the vagina and around the anus.
- Blood pressure. In a normal pregnancy, blood pressure never increases, in fact, it decreases slightly. Progesterone causes blood vessels to relax, giving them increased elasticity and facilitating circulation. By midpregnancy, diastolic pressure goes down somewhat, then returns to prepregnancy levels at about 36 weeks.
- Preeclampsia. The causes of preeclampsia, a serious complication also called pregnancy-induced hypertension, are unknown. Preeclampsia occurs only during pregnancy and the postpartum period and affects both the mother and the unborn baby. The mother's blood pressure rises, protein appears in the urine, and there may be water retention. These symptoms are probably caused by damage to the mother's blood vessels, liver, and kidney, possibly by substances from the placenta. Globally, preeclampsia is a leading cause of maternal and infant illness and death.
- Heart changes. The heart enlarges, works harder, and beats more rapidly. It must do this to compensate for the increased volume of blood, and also for the pressure placed on the lower aorta (located in the abdomen) and the inferior vena cava (found on the right side of body) by the enlarging uterus. The heart also changes position: the growing uterus causes the diaphragm to displace the heart, shifting it upward and to the left.
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