Basal Temps and how they work

[mrs_abbott]

Ok, now bear with me cuz I haven’t had formal training on NFP or anything but a question arose when talking with a friend of mine about NFP.
You know how you’re supposed to take your temps every morning at the same time? What if you’re off a few hours, like sleep in late for a couple of days? Will that affect your fertility reading?

 

[C.T]

Yes, sleeping in would throw off your temps. Ovusoft (or I think they are calling it TCOYF software now) subtracts .1 for every 20 minutes you sleep in, I think. So, if you usually wake at 6:30 but sleep in until 7:10 on day, and your temp that morning is 97.4, Ovusoft knocks it down to 97.2. If I’m remembering the formula correctly. Two other options are to just ignore that temp (it’ll take a little longer to have enough days of elevated temps to be sure of ovulation having occurred, or just set your alarm for the usual wakeup time even on weekends, and wake up just long enough to take your temp, then go back to sleep.