The heart adapts to the increased cardiac demand that occurs during pregnancy in many ways.
- Cardiac output (Lit./Min.): 6.26
- Stoke Volume (Ml.): 75
- Heart Rate (Per min.): 85
- Blood Pressure: Unaffected
Cardiac output increases throughout early pregnancy, and peaks in the third trimester, usually to 30-50% above baseline. Estrogen mediates this rise in cardiac output by increasing the pre-load and stroke volume, mainly via a higher overall blood volume (which increases by 40–50%). The heart rate increases, but generally not above 100 beats/ minute. Total systematic vascular resistance decreases by 20% secondary to the vasodilatory effect of progesterone. Overall, the systolic and diastolic blood pressure drops 10–15 mm Hg in the first trimester and then returns to baseline in the second half of pregnancy. All of these cardiovascular adaptations can lead to common complaints, such as palpitations, decreased exercise tolerance, and dizziness.
Uterine Compression of IVC and Pelvic Veins. Displacement of PMI by Uterus
Uterine enlargement beyond 20 weeks’ size can compress the inferior vena cava, which can markedly decrease the return of blood into the heart or preload. As a result, healthy pregnancy patients in a supine position or prolonged standing can experience symptoms of hypotension.
Pregnancy world 