There are several physiological changes in a mother during pregnancy, in addition to changes in the size of the uterus and changes in the mammary glands. The mother must eat, breathe, and eliminate wastes for both herself and her developing fetus, which is totally dependent upon the mother. The mother’s respiratory rate goes up so her lungs can deliver the extra oxygen and remove the excess carbon dioxide generated by the fetus. The maternal blood volume increases by nearly 50 percent by the end of a pregnancy, since blood flowing into the placenta reduces the volume of blood throughout the rest of the cardiovascular system. Because the mother must also nourish the fetus, she may feel hungry more often, and her nutritional requirements increase 10 to 30 percent. The maternal glomerular filtration rate increases by approximately 50 percent to excrete the fetus’s waste. Consequently, the combination of increased weight and pressure on the mother’s urinary bladder and the elimination of additional waste products lead to more frequent urination.