**Core Concept**
In pregnancy, the goal is to maintain blood pressure while ensuring fetal safety. Certain anti-hypertensive medications can cross the placenta and affect fetal development. The choice of antihypertensive agent is crucial during pregnancy.

**Why the Correct Answer is Right**
The correct answer is **Methyldopa** is not correct, however, I will provide you with a correct answer in the next part. Methyldopa is often used in pregnancy, but not the correct answer here. The correct answer is **ACE inhibitors**. ACE inhibitors can cause fetal renal damage and are absolutely contraindicated in pregnancy. They can lead to oligohydramnios (reduced amniotic fluid) and pulmonary hypoplasia in the fetus. This is because ACE inhibitors inhibit the conversion of angiotensin I to angiotensin II, which is essential for maintaining fetal renal function and promoting fetal lung development.

**Why Each Wrong Option is Incorrect**
* **Option A:** Methyldopa is a centrally acting antiadrenergic agent that is often used in pregnancy. It does not cross the placenta and is considered safe for use during pregnancy.
* **Option B:** Labetalol is a mixed alpha/beta-adrenergic antagonist that is commonly used in pregnancy. It is considered safe and effective for controlling blood pressure in pregnant women.
* **Option C:** Hydralazine is a vasodilator that is often used in pregnancy to control severe hypertension. It does not cross the placenta and is considered safe for use during pregnancy.

**Clinical Pearl / High-Yield Fact**
Remember that ACE inhibitors are absolutely contraindicated in pregnancy due to the risk of fetal renal damage and other complications.

**Correct Answer:** D.