**Core Concept**
Hyperventilation can lead to respiratory alkalosis, which can cause a series of physiological changes that affect the body's acid-base balance and overall homeostasis. This can be particularly concerning in pregnant women, as it can impact both the mother and the fetus.

**Why the Correct Answer is Right**
When a person hyperventilates, they blow off more carbon dioxide (CO2) than usual, leading to a decrease in CO2 levels in the blood. This decrease in CO2 causes the blood pH to rise, resulting in respiratory alkalosis. In pregnant women, the increased levels of progesterone can exacerbate this effect, leading to a more pronounced alkalotic state. Furthermore, the increased CO2 loss can cause a decrease in the concentration of bicarbonate ions (HCO3-) in the blood, as the kidneys try to compensate for the alkalosis by excreting more HCO3-.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the physiological consequences of hyperventilation in a pregnant woman.

**Option B:** This option is incorrect because while hyperventilation can cause a decrease in CO2 levels, it does not directly lead to a decrease in maternal blood pressure.

**Option C:** This option is incorrect because while hyperventilation can cause respiratory alkalosis, it does not directly lead to a decrease in fetal heart rate.

**Clinical Pearl / High-Yield Fact**
In pregnant women, hyperventilation can cause a condition known as "respiratory alkalosis," which can lead to a decrease in uterine blood flow and potentially impact fetal well-being. This is a critical consideration for healthcare providers managing labor and delivery.

**Correct Answer:** C. **Decreased uteroplacental blood flow**