I'm currently playing around with light therapy and darkness therapy in the hope that it will regulate my hormones, and have just found a couple of interesting articles about melatonin in women with PMDD
here and
here. Light therapy is already a well-known treatment for depression, and darkness therapy is beginning to gain some support, particularly for bipolar disorder. For those of you interested in finding out more, I've written an article about all of this on another forum which I can copy in (it's member-protected) if anyone wants.
Low Blue Lights is generally a good website on darkness therapy. Remember that treatments which improve fertility frequently improve PMDD as well.
ETA: Aha, another useful article
here.