Final answer:
Baseline measurements are the measurements recorded at the patient's first visit and serve as the standard for comparison in subsequent measurements.
Step-by-step explanation:
The measurements recorded at the patient's first visit are known as the baseline measurements. These baseline measurements serve as the standard against which all subsequent measurements are compared. They provide a starting point for tracking changes or progress in the patient's condition over time. For example, in a medical study, baseline measurements may include vital signs, laboratory test results, or physical examination findings.