:?: what would be or is considered the most reliable route for taking a basal body temperature? Is it rectally, orally or is it also done vaginally? I know the thermometers that are out there for this are gradiated differently than fever thermometers, and that now they're also available as digital models as well as the glass type (note: I am aware of the concerns about mercury).

I spoke with my girlfriend on this, and I was very honest, I told her, I suspected, though didn't know that like a fever thermometer reading, rectally is most accurate. I realize the use of a thermometer rectally may not be her particular preference. Any info, comments or thoughts on this?