The only thing I "know" about coffee, is that newlyweds (past) were asked not to drink it. If the missus drank coffee, offspring didn't show up quite as fast as when they didn't. It's an old wives tale - but the funny thing is that in the mid-nineties I saw some study that revealed seven-cups a day would increase estrogen in women. Like the pill! How the heck did the old wives know this? ;) Not a diuretic for me.
* I drink 7-9 cups of coffee each day, never wee much but do have yellow teeth.