Physiological anaemia during pregnancy is mainly the result of?

IGNOU Post B. SC. Nursing entrance -2021

Obstetrics & Gynaecology

Easy

Appeared in: IGNOU Post B. SC. Nursing entrance -2021

Explanation

Physiological anemia during pregnancy is a normal finding resulting from hemodilution.
This occurs because the maternal plasma volume expands significantly (by 40-50%), while the red blood cell (RBC) mass increases to a lesser extent (20-30%).
The disproportionately larger increase in plasma volume dilutes the concentration of hemoglobin and red blood cells, leading to a lower hematocrit.
This adaptation supports increased metabolic demands and provides adequate perfusion to the placenta and fetus.

Option B: This causes iron-deficiency anemia, which is a pathological condition, not the normal physiological anemia of pregnancy. Iron deficiency requires medical intervention.
Option C: This is factually incorrect. Erythropoiesis (red blood cell production) is actually stimulated and increases during pregnancy to meet the higher demand for oxygen transport.
Option D: While the liver's metabolic and detoxification functions are increased during pregnancy, this process is not the primary cause of the hematological changes that define physiological anemia.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of physiological anemia in pregnancy as background academic context rather than a clinical decision trigger.
It is crucial for nurses to differentiate physiological anemia from pathological anemia to ensure appropriate care. Physiological anemia is a normal adaptation and does not require treatment.
Nurses monitor hemoglobin (Hb) and hematocrit (Hct) levels throughout pregnancy. The lower limit of normal is generally considered 11 g/dL in the first and third trimesters and 10.5 g/dL in the second trimester.
What if? If a pregnant patient's hemoglobin drops to 9.5 g/dL in the second trimester and she complains of excessive fatigue and pallor, the nurse should suspect pathological iron-deficiency anemia rather than just physiological changes. This would warrant notifying the provider for further investigation and potential iron supplementation.

How to Approach the Question

First, identify the key terms in the question: 'Physiological anaemia' and 'pregnancy'. The word 'physiological' is critical, as it implies a normal, expected change, not a disease process.
Evaluate each option in the context of normal pregnancy changes.
Option A, 'Increased blood volume of the mother', describes a well-known, major physiological adaptation of pregnancy.
Consider how a large increase in blood volume would affect the concentration of its components. Recall that plasma volume increases more than red cell mass.
Options B ('Decreased dietary intake of iron') and C ('Decreased erythropoiesis') describe pathological conditions or incorrect physiological statements. Iron deficiency causes pathological anemia, and erythropoiesis actually increases.
Option D ('Increased detoxification demands') is a real change in pregnancy but is not the direct mechanism for the change in blood concentration.

Concept Tested & Keywords

QJ-CLxN7sjLwNBZlw_ZHRd

E6 Obstetrics Williams p. 44-63

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

E6 Medicine Davidson Principles Practice 24e p. 961-963