Work Discrimination?

i'm stunned too!  You need to find someone who knows employment law (I think there is a thread somewhere here), but my experience tells me that the employer has to treat everyone in similar fasion: If Employee A used FMLA, had a baby, and received a merit raise, then Employee B, who also took FMLI, for whatever reason, must similarly be eligible for a raise. 

It sounds as though you work for a fairly large corporation, which has significant advantages for you.  Your human resources department will be acutely aware that there are legal protections in place for those with discrimination complaints, as well as significant corporate financial penalties for failure to follow through or allow payback.   Most likely, your department budget is under pressure, but your supervisor clearly indicated that her refusal to recommend a raise for you is not a department-wide salary freeze, and not a performance issue, but specifically your five weeks of authorized, and legally protected, absence.  Even worse, she indicated (hopefully incorrectly) that this might be a corporate policy. 

In my ever so humble opinion, you really need to follow up on this, but only after you have some more concrete information about how, and how not, to proceed.   I've seen those with human resource and employment law experience post in various threads here.  Perhaps you could PM a couple of them?

I'm rooting for a nice, big, juicy, raise!