Is It Ob-Gin or Ob-Gyne?

Saying "obstetrician-gynecologist" is a mouthful for most people, and it's probably the most abbreviated specialty in medicine, both spoken and written. However, there doesn't seem to be a consensus on how to pronounce OB-GYN. First, is it the two-syllable "O-B" or the monosyllabic "Ob"? Second, is it "gin" or "gyne" (like "Lyme")? I wonder if you have a preference. I know I do.