**Core Concept**
The management of urinary tract infections (UTIs) during pregnancy requires careful consideration of the antibiotic choice to ensure both efficacy and safety for the mother and the fetus. **Urinary tract infections** are common during pregnancy, and their treatment is crucial to prevent complications such as **pyelonephritis**.

**Why the Correct Answer is Right**
Given the context, the correct answer is often an antibiotic that is effective against the common pathogens causing UTIs, such as **Escherichia coli**, and has a good safety profile during pregnancy. **Nitrofurantoin** and **cephalosporins** are generally considered safe, but the choice may depend on the specific trimester and local resistance patterns.

**Why Each Wrong Option is Incorrect**
**Option A:** May not be the first choice due to potential resistance issues or side effects.
**Option B:** Could be incorrect if it's an antibiotic not typically recommended in pregnancy due to safety concerns.
**Option D:** Might be wrong if it represents an antibiotic with a higher risk profile for the fetus.

**Clinical Pearl / High-Yield Fact**
It's crucial to choose an antibiotic that is effective and safe for both the mother and the fetus, considering factors like resistance patterns and the stage of pregnancy.

**Correct Answer:** D. Nitrofurantoin