How likely would I be to convince my boss that I can work from home the first year after giving birth?

I work for a fast growing church as their director of communications, but basically I am their graphic designer. I maintain the website, the biweekly newsletter, the Sunday bulletins, and many other publications. I feel confident that I could do my job from home if I had to (new born baby). How should I go about convincing my boss (the Rector) that I should be allowed to do this?