I'm on the pill and don't notice any blips around my period. I went on the pill when I was about 18, because my mom had ovarian cancer at 30 and many studies have shown that women who take the pill have a lower incidence of ovarian cancer than those who do not. I went off the pill about 6 months before my husband and I started TTC (trying to conceive) our first child. My symptoms of UC started about 4 weeks after the birth of our son. I breastfed him until he was about 8-9 weeks old and had to stop because my supply dropped so low. At that point, I went back on the pill, but I hadn't really had a period yet at that point.
So, I can't really say if the pill makes things better or not UC-wise. Before I went on the pill, though, I'd often have diarrhea in the days leading up to my period. I don't think it had anything to do with UC, but I do think it was hormone-related.
Status: Remission since May 2009!
Symptoms began in November 2008, ~4 weeks after giving birth to my son.
Diagnosed with pancolitis on 1/30/09
Currently meds: Apriso (4 0.375g pills ONCE!! daily), mesalamine enema twice weekly, Natural Factors Ultimate probiotic 12/12 Formula, and Zoloft (currently tapering; 12.5 mg).