The first mammogram a woman has is referred to as her ___________ exam.

The term "baseline" in the context of mammography refers specifically to the first mammogram a woman undergoes. This initial exam serves as a reference point for comparison in future mammograms. Establishing a baseline is crucial because it allows healthcare providers to identify any changes in breast tissue over time, which can be indicative of potential abnormalities or developments such as tumors.

In subsequent mammograms, the baseline study is utilized to assess any changes or developments in breast density, size, shape, and any other important characteristics. This comparison is essential for accurate diagnosis and for making informed decisions about breast health management moving forward.

Other options do not accurately capture this function. "Initiation" might suggest the beginning of screening but lacks the specific connotation of serving as a reference point. "Original" does not have a standardized meaning in this context. "Prior" implies something that has occurred before, which does not fit the concept of a first mammogram used as a benchmark. Hence, "baseline" is the most appropriate and widely accepted term for this important aspect of mammographic evaluation.