**Core Concept**
Normal pregnancy can be continued in the presence of certain medical conditions, provided they are well-managed. The key principle is to balance the health of the mother with the well-being of the fetus. **Chronic hypertension** is one such condition where, with proper management, pregnancy can proceed.

**Why the Correct Answer is Right**
In cases of well-controlled **chronic hypertension**, the risk to the mother and fetus can be minimized with close monitoring and appropriate medical intervention. This includes regular blood pressure checks, **fetal monitoring**, and adjustments to medication as necessary to prevent complications such as **preeclampsia**.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because uncontrolled **diabetes mellitus** poses significant risks to both mother and fetus, including congenital malformations and complications during delivery.
**Option B:** Incorrect as **severe heart disease** can lead to serious maternal and fetal morbidity, making continued pregnancy risky without significant medical intervention.
**Option C:** Incorrect because **chronic renal failure** can complicate pregnancy, leading to issues such as **preeclampsia** and worsening renal function.

**Clinical Pearl / High-Yield Fact**
It's crucial to differentiate between conditions that can be safely managed during pregnancy and those that pose significant risks. **Chronic hypertension**, when well-controlled, allows for the continuation of a normal pregnancy, highlighting the importance of preconception counseling and close monitoring during pregnancy.

**Correct Answer:** D. Chronic hypertension.