## Core Concept
During pregnancy, numerous physiological changes occur to accommodate the growing fetus and prepare the mother's body for childbirth. These changes affect various systems, including cardiovascular, respiratory, renal, and metabolic systems. Understanding these adaptations is crucial for managing pregnant women.

## Why the Correct Answer is Right
The correct answer involves identifying changes that are **not** likely to occur during pregnancy. Typically, pregnancy is associated with increased blood volume, cardiac output, and glomerular filtration rate (GFR), among other changes. For instance, blood pressure often decreases in early pregnancy due to vasodilation and then increases as the pregnancy progresses.

## Why Each Wrong Option is Incorrect
- **Option A:** Increased blood volume and cardiac output are expected changes.
- **Option B:** Enhanced renal function, indicated by increased GFR, is a common adaptation.
- **Option C:** Metabolic changes include increased insulin resistance.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that despite an increase in GFR, the pregnancy-induced increase in blood volume and GFR can dilute serum creatinine levels, potentially masking renal dysfunction.

## Correct Answer Line
**Correct Answer: D.**