**Core Concept**
The hemoglobin levels in pregnant females are influenced by the increased blood volume and erythropoietin levels during pregnancy. Hemoglobin levels are typically lower in pregnant women compared to non-pregnant women due to the physiological changes.

**Why the Correct Answer is Right**
During pregnancy, the blood volume increases by approximately 40-50% to meet the oxygen demands of the fetus. However, the erythropoietin levels, which stimulate red blood cell production, also increase. As a result, the hematocrit (the proportion of blood volume occupied by red blood cells) decreases, leading to lower hemoglobin levels. In addition, the increased blood volume dilutes the concentration of hemoglobin, further contributing to the decrease in hemoglobin levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question, as it appears to be a non-sequitur.

**Option B:** This option is incorrect as it does not specify the expected decrease in hemoglobin levels during pregnancy.

**Option C:** This option is incorrect as it does not provide a specific value for the expected decrease in hemoglobin levels during pregnancy.

**Clinical Pearl / High-Yield Fact**
A decrease in hemoglobin levels during pregnancy is a normal physiological change, and hemoglobin levels typically return to normal within 6-8 weeks postpartum. It's essential to diagnose and manage any underlying conditions that may contribute to anemia in pregnant women.

**Correct Answer:** D.