Physiological Maternal Changes in Prenatal Period (I) 孕妇的产前期生理学变化 (1)
A. Cardiovascular system 心血管系统
1. Circulating blood volume increases, plasma increases, and total red blood cell volume increases (total volume increases by approximately 40% to 50%).
2. Physiological anemia occurs as the plasma increase exceeds the increase in production of red blood cells.
3. Iron requirements are increased. 铁的需求增加。
4. Heart size increases, and the heart is elevated slightly upward and to the left because of displacement of the diaphragm as the uterus enlarges (FIGURE Below).
5. Retention of sodium and water may occur.
FIGURE Changes in position of heart, lungs, and thoracic cage in pregnancy. Broken line, nonpregnant state; solid line, change that occurs in pregnancy.