Final answer:
During pregnancy, the maternal PaO2 and PaCO2 levels undergo changes due to the increased oxygen demands of the fetus. The respiratory minute volume increases to meet the demands, but the growing uterus can cause shortness of breath. As the fetus descends lower in the pelvis, the symptoms of dyspnea may improve.
Step-by-step explanation:
During pregnancy, maternal PaO2 (partial pressure of oxygen) and PaCO2 (partial pressure of carbon dioxide) go through certain changes. The respiratory minute volume, which is the volume of gas inhaled or exhaled by the lungs per minute, increases by 50 percent to meet the oxygen demands of the fetus and the increased metabolic rate of the mother. The growing uterus exerts pressure on the diaphragm, reducing the volume of each inspiration and potentially causing shortness of breath. Towards the end of pregnancy, the fetus descends lower in the pelvis, relieving dyspnea.
Learn more about maternal PaO2 and PaCO2 during pregnancy