Phenylephrine can cause fetal hypoxia due to:

Phenylephrine can cause fetal hypoxia due to:

• A. Increased uterine blood flow
• B. Reflex tachycardia
• C. Vasoconstriction leading to reduced uterine blood flow
• D. Decreased maternal heart rate

Answer: (C)

Phenylephrine can cause fetal hypoxia because it is a selective alpha-1 vasopressor that causes peripheral vasoconstriction. This constriction raises maternal blood pressure but can also tighten the uterine arteries, reducing uteroplacental blood flow. When placental perfusion falls, fetal oxygen delivery drops, increasing the risk of fetal hypoxia. While phenylephrine can induce a reflex change in heart rate, it more commonly causes bradycardia rather than tachycardia, and the key issue here is the decrease in uterine/placental blood flow. Options suggesting increased uterine blood flow, tachycardia, or decreased maternal heart rate as the primary mechanism don’t capture the direct cause of fetal hypoxia.

Phenylephrine can cause fetal hypoxia because it is a selective alpha-1 vasopressor that causes peripheral vasoconstriction. This constriction raises maternal blood pressure but can also tighten the uterine arteries, reducing uteroplacental blood flow. When placental perfusion falls, fetal oxygen delivery drops, increasing the risk of fetal hypoxia. While phenylephrine can induce a reflex change in heart rate, it more commonly causes bradycardia rather than tachycardia, and the key issue here is the decrease in uterine/placental blood flow. Options suggesting increased uterine blood flow, tachycardia, or decreased maternal heart rate as the primary mechanism don’t capture the direct cause of fetal hypoxia.