& x20;What is the primary cause of mild breathlessness experienced during normal pregnancy? - INI-CET EXAM -2026

INI-CET EXAM -2026

Obstetrics & Gynaecology

Easy

Appeared in: INI-CET EXAM -2026

Explanation

During pregnancy, the hormone progesterone acts as a primary respiratory stimulant.
Progesterone increases the sensitivity of the respiratory center in the brain to carbon dioxide (CO2).
This heightened sensitivity leads to an increased respiratory drive, causing the pregnant woman to breathe more deeply (increased tidal volume) and slightly more frequently.
This physiological hyperventilation results in a sensation of breathlessness or dyspnea, which is a common and normal experience in pregnancy.

Option A: Tidal volume, which is the amount of air moved in and out with each normal breath, actually increases by 30-40% during pregnancy to meet higher oxygen demands. A decrease would lead to hypoventilation, not the characteristic hyperventilation of pregnancy.
Option C: Oxygen consumption and intake increase by about 20% during pregnancy to support the growing fetus, placenta, and increased maternal metabolic rate. Reduced intake would be pathological.
Option D: The progesterone-induced hyperventilation causes more CO2 to be exhaled, leading to a decrease in arterial PCO2 levels. This creates a state of compensated respiratory alkalosis, which facilitates the transfer of CO2 from the fetus to the mother.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological respiratory changes during pregnancy as background academic context rather than a clinical decision trigger.
It is crucial for nurses to recognize that mild dyspnea is a normal physiological change in pregnancy and to reassure the patient.
Nurses must be able to differentiate this normal breathlessness from pathological causes, such as pulmonary embolism, asthma, pneumonia, or peripartum cardiomyopathy.
Red flags indicating a pathological cause include sudden onset of severe breathlessness, chest pain, coughing up blood (hemoptysis), fever, or signs of respiratory distress like cyanosis or use of accessory muscles.

How to Approach the Question

First, identify the core concept of the question, which is the physiological cause of a common symptom in pregnancy (breathlessness).
Recall the major hormonal and physiological changes that occur during pregnancy, particularly focusing on the respiratory system.
Consider the role of progesterone, a key hormone in pregnancy, and its known effects on various body systems.
Evaluate each option against the known physiological adaptations of pregnancy:
Does tidal volume increase or decrease? (It increases). Eliminate A.
Does oxygen demand increase or decrease? (It increases). Eliminate C.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 49-69