I was on pred and birth control at the same time and none of my docs said anything about
it, so I would assume it's OK.
I personally used birth control for many years, because my mom had ovarian cancer at 30, and the risk of developing ovarian cancer is reduced by using it.
http://www.cancer.org/Cancer/news/News/birth-control-pill-use-cuts-ovarian-cancer-risk
I had been on it for about 11 years (continuously) when I stopped taking it in summer or fall of 2007, because my husband and I knew we wanted to start trying for our first child within a few months, and I wanted to give my cycle time to regulate. I got pregnant in February 2008 and had my son in October -- my UC symptoms started a few weeks after he was born. However, I don't think stopping the pill is what triggered my UC, but I guess I can't really rule that out completely.
Another reason I went on the pill is because every few cycles, I would have horrible bowel issues in the one or two days immediately before my period and on the day is started. I'd even have drops in my blood pressure that were extreme enough I'd almost pass out! After starting the pill, that never happened again.
I was off the pill for a short while in early/mid 2011 because my husband and I thought we were maybe going to be ready to TTC our second child and because we moved, and therefore had new insurance, and I didn't want to screw with transferring my prescription. I noticed that I'd quite often have bowel issues (although not so severe as before) around the time my period was to start. I started birth control again because of that, then stopped after just a few months b/c my husband and I decided the time was finally right to TTC, and I got pregnant pretty quickly.