Final answer:
Supine hypotensive syndrome is the cause of diaphoresis and dizziness in a pregnant patient in the dorsal recumbent position.
Step-by-step explanation:
The cause of diaphoresis and dizziness in a pregnant patient in the dorsal recumbent position is supine hypotensive syndrome. Supine hypotensive syndrome occurs when the pregnant uterus compresses the inferior vena cava and decreases blood flow to the heart. This compression can lead to decreased blood pressure and reduced blood flow to the brain, resulting in symptoms such as diaphoresis (excessive sweating) and dizziness.