Physiological changes in pregnancy include which of the following?

KPSC Staff Nurse - 2016

Obstetrics & Gynaecology

Easy

Appeared in: KPSC Staff Nurse - 2016

Explanation

During pregnancy, plasma volume increases significantly (by 40-50%), while red blood cell (RBC) mass increases to a lesser extent (20-30%).
This disproportionate increase in plasma volume relative to RBCs leads to hemodilution.
Hemodilution results in a lower concentration of hemoglobin (Hb) and hematocrit, a condition known as 'physiological anemia of pregnancy'.
This is a normal adaptation to pregnancy and is not considered a pathological state unless Hb levels fall below specific thresholds (e.g., less than 11 g/dL in the first trimester).

Option A: The increase in blood volume during pregnancy is substantial but does not reach 100%. The typical increase is between 30% and 50%.
Option C: Systemic vascular resistance (peripheral resistance) decreases during pregnancy by about 20%. This is due to the vasodilatory effects of hormones like progesterone and prostaglandins.
Option D: Cardiac output increases significantly during pregnancy, by 30-50%, to supply the growing fetus and placenta and meet the mother's increased metabolic needs.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cardiovascular and Hematological Changes in Pregnancy as background academic context rather than a clinical decision trigger.
It is crucial for nurses to differentiate between physiological anemia of pregnancy and pathological anemia. While a slight drop in Hb is normal, levels below 11 g/dL in the first and third trimesters, or below 10.5 g/dL in the second, warrant investigation for iron deficiency or other causes.
Understanding these cardiovascular changes helps explain why pregnant women may feel dizzy or have lower blood pressure readings, especially in mid-pregnancy, despite having more blood.
Nurses should educate pregnant women about the importance of adequate iron and folic acid intake to support the increased production of red blood cells and prevent true iron-deficiency anemia.

How to Approach the Question

Identify the core of the question: It asks for a correct statement about the normal physiological changes that occur during pregnancy.
Evaluate each option based on your knowledge of maternal physiology.
Recall the changes in blood components: Plasma volume increases more than red blood cell mass. This leads to hemodilution. How does this affect hemoglobin (Hb)? It decreases its concentration.
Analyze Option B ('Decrease in Hb'). This aligns with the concept of physiological anemia. Keep it as a strong candidate.
Analyze Option A ('Increase in blood volume by 100%'). Recall the approximate percentage increase. 30-50% is the typical range. 100% is too high. Eliminate this option.
Analyze Option C ('Peripheral resistance 50% increases'). Recall the effect of pregnancy hormones on blood vessels. Progesterone causes vasodilation, which decreases resistance. Eliminate this option.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 61-63

E6 Obstetrics Williams p. 30-50

E6 Physiology Essentials Sembulingam 10e Part 2 p. 140-142