**Core Concept**
The management of hypertension in pregnancy is crucial to prevent complications such as preeclampsia and fetal growth restriction. Antihypertensive medications used in pregnancy must be chosen carefully to minimize risks to both mother and fetus.

**Why the Correct Answer is Right**
Methyldopa is commonly used in pregnancy due to its long-standing safety profile and effectiveness in controlling blood pressure. It works by stimulating the alpha-2 adrenergic receptors in the brain, which decreases sympathetic outflow and results in vasodilation. However, some antihypertensive medications are contraindicated in pregnancy due to potential fetal harm.

**Why Each Wrong Option is Incorrect**
**Option A:** Methyldopa is used in pregnancy, making it incorrect.
**Option B:** Labetalol is also used in pregnancy, particularly for its rapid onset of action and ability to control blood pressure in acute hypertensive crises.
**Option C:** Nifedipine, a calcium channel blocker, is used in pregnancy for the treatment of hypertension, especially in the third trimester.
**Option D:** Hydralazine is a vasodilator that is used in pregnancy for the acute management of severe hypertension and preeclampsia.

**Clinical Pearl / High-Yield Fact**
When managing hypertension in pregnancy, it is essential to remember that methyldopa is generally safe and can be used as a first-line treatment, whereas other antihypertensive medications may require more caution or alternative agents.

**Correct Answer: A. Methyldopa is not used in pregnancy.**