Final answer:
Significant hemodynamic changes during the third trimester include increased blood volume, compression of pelvic blood vessels by the growing uterus leading to conditions like varicose veins and hemorrhoids, and hormonal changes affecting maternal metabolism and appetite.
Step-by-step explanation:
Hemodynamic Effects of Pregnancy in the Third Trimester:
During the third trimester of pregnancy, there are significant hemodynamic changes that have important clinical considerations for the expecting individual. The blood volume increases by about 30 percent or approximately 1-2 liters from preconception to accommodate fetal nourishment and waste removal. Consequently, both pulse and blood pressure may rise moderately.
The growing fetus and expanding uterus can compress pelvic blood vessels, leading to a decrease in venous return from the lower extremities and potential development of conditions such as varicose veins or hemorrhoids. The rate of urine production also increases and the expanded uterus can cause more frequent urination by compressing the bladder. The hormonal changes including increases in thyroid hormone can raise the maternal metabolic rate which may affect appetite as well as cause hot flashes. Weight gain accelerates with changes in the maternal anatomy including an increase in breast tissue, blood volume and fat storage reserved for breastfeeding demands.