## **Core Concept**
The cardiac output increases throughout pregnancy, peaking in the late second to early third trimester. This increase is essential to meet the metabolic demands of the mother and the fetus. The **cardiovascular system** undergoes significant changes during pregnancy, including an increase in blood volume, heart rate, and contractility.

## **Why the Correct Answer is Right**
The maximum increase in cardiac output occurs by the **28-32 weeks** of gestation, which corresponds to option . This increase is primarily due to the **augmentation of stroke volume** and a **significant increase in heart rate**. The rise in cardiac output is crucial for delivering oxygen and nutrients to the growing fetus and for preparing the mother's body for the blood loss that occurs during delivery.

## **Why Each Wrong Option is Incorrect**
* **Option A:** . This is too early for the peak increase in cardiac output. Although cardiac output starts increasing early in pregnancy, it doesn't reach its maximum until later.
* **Option B:** . This option might seem plausible but is not the correct timeframe for the maximum increase.
* **Option D:** . This is considered late for the peak increase; cardiac output usually peaks before this stage.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **cardiac output increases by approximately 40-50% by the end of the second trimester**. This significant increase is vital for the health of both the mother and the fetus. Clinicians must consider these changes when managing pregnant patients with pre-existing cardiac conditions.

## **Correct Answer:** . 28-32 weeks.