Can you consider FMLA leave in employee’s review?

Q. We have an employee who takes a lot of intermittent FMLA leave for medical reasons. We are writing her performance appraisal and need to address topics such as dependability, reliability, etc. Her FMLA leaves are affecting these issues. Does the law regulate whether we can lower her performance review or merit increases based on her FMLA leave? —G.L., Massachusetts ...