This is completely anecdotal... I too have had a long history of
     migraines (now recently diagnosed as migraibe-like cluster headaches).
     I also had a migraine-free pregnancy.  When I first began
     breastfeeding my daughter I found the headaches returning.  These
     quickly subsided as i became more comfortable with the process
     (emotionally ) and as my body mechanics improved ( We positioned
     ourselves properly and comfortably with my feet slightly elevated and
     my neck in a good position or our favorite... lying down), and with
     proper positioning at the breast and no more nipple pain therefor no
     tense muscles and no clenched teeth.

     For what it's worth
     Paula