**Question:** All are CVS changes in pregnancy except -

A. Increased heart rate
B. Reduced heart rate variability
C. Reduced stroke volume
D. Decreased cardiac output

**Core Concept:** Cardiovascular changes in pregnancy are a series of physiological adaptations that help maintain maternal circulation and fetal oxygenation. These changes include alterations in heart rate, cardiac output, and blood volume, among others.

**Why the Correct Answer is Right:** Option D, "Decreased cardiac output", is incorrect because cardiac output is actually increased during pregnancy due to several factors, including a decrease in plasma viscosity, increased cardiac preload, and increased cardiac afterload. This increase in cardiac output ensures adequate blood flow to the growing fetus and placenta, while maintaining blood pressure and oxygen delivery to the mother.

**Why Each Wrong Option is Incorrect:**

A. Increased heart rate: Although heart rate increases slightly during pregnancy, it remains within the normal range. This compensatory mechanism helps maintain coronary blood flow to the uterus and placenta.

B. Reduced heart rate variability: Heart rate variability is reduced in early pregnancy due to the increased sympathetic tone. However, this is a normal adaptation that allows for better maternal adaptation to varying demands.

C. Reduced stroke volume: Stroke volume is not significantly reduced during pregnancy. In fact, it increases slightly to meet the increased cardiac output requirements.

**Clinical Pearl / High-Yield Fact:**

Cardiac output in pregnancy is mainly regulated by the autonomic nervous system, particularly the sympathetic and parasympathetic divisions. In the first trimester, the sympathetic tone increases, leading to tachycardia and reduced heart rate variability. As pregnancy progresses, the parasympathetic tone increases, resulting in bradycardia and improved heart rate variability. This autonomic balance helps maintain maternal adaptation to the increased cardiovascular demands of pregnancy and fetal growth.

**Correct Answer:** C. Reduced stroke volume is not significantly reduced during pregnancy. In fact, it increases slightly to meet the increased cardiac output requirements.