**Question:** A 20 weeks pregnant woman is referred to your office with newly diagnosed hypertension. You are concerned that the fetus and placenta may be compromised. To assess fetal and placental health, which of the following hormone measurements would be most informative?

A. Plasma renin activity
B. Plasma aldosterone concentration
C. Plasma aldosterone concentration
D. Plasma aldosterone concentration

**Correct Answer:** D. Plasma aldosterone concentration

**Core Concept:**
Hypertension in pregnancy, particularly when associated with proteinuria, can lead to maternal complications like preeclampsia and fetal/neonatal complications like intrauterine growth restriction and preterm birth. Monitoring the hormonal profile can help assess fetal and placental health.

**Why the Correct Answer is Right:**
Among the given options, plasma aldosterone concentration (option D) is the most informative test to assess fetal and placental health. Aldosterone is a hormone secreted by the adrenal glands in response to low blood sodium levels and high blood potassium levels. In pregnancy, increased aldosterone levels can indicate the presence of preeclampsia, a hypertensive disorder complicating pregnancy.

**Why Each Wrong Option is Incorrect:**

A. Plasma renin activity (option C) is a precursor to aldosterone production. While elevated renin levels can indicate placental insufficiency, it is not as specific as aldosterone for fetal and placental health assessment.

B. Plasma aldosterone concentration (option C) is less specific than plasma aldosterone concentration (option D) for assessing fetal and placental health.

C. Plasma aldosterone concentration (option B) is less specific than plasma aldosterone concentration (option D) for assessing fetal and placental health.

**Clinical Pearl:**

Monitoring aldosterone levels can help identify preeclampsia, a major cause of maternal and fetal morbidity and mortality in pregnancy. Early detection and management of preeclampsia can prevent severe maternal complications, such as eclampsia, and improve fetal outcomes like intrauterine growth restriction and preterm birth.