**Core Concept**
Pregnancy-induced changes in renal function and blood flow lead to increased renal plasma flow and glomerular filtration rate, affecting the composition of urine.

**Why the Correct Answer is Right**
The increased renal plasma flow and glomerular filtration rate during pregnancy lead to increased clearance of various substances, including proteins and electrolytes. The normal increase in renal blood flow and glomerular filtration rate results in the presence of proteinuria, specifically albuminuria, in the urine of pregnant women in the third trimester.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while glycosuria may be seen in pregnancy due to increased glucose load, it is not a specific indicator of increased renal plasma flow.
**Option B:** This option is incorrect because the presence of leukocyte esterase and nitrites in the urine is indicative of a urinary tract infection, not a normal finding in pregnancy.
**Option C:** This option is incorrect because the presence of hematuria is not a normal finding in pregnancy and requires further investigation.

**Clinical Pearl / High-Yield Fact**
Pregnant women in the third trimester may exhibit proteinuria due to the increased glomerular filtration rate and renal plasma flow, but this does not necessarily indicate preeclampsia.

**Correct Answer:** C. Proteinuria