Basal Body Temperature (BBT) Method

Basal Body Temperature

Woman takes her body temperature at the same time each morning before getting out of bed observing for an increase of 0.2 to 0.5 degrees C.              

How it works: 
Prevents pregnancy by avoiding unprotected vaginal sex during fertile days
Effectiveness to prevent pregnancy: 
99% effective with correct and consistent use. 75% with typical use of FABM (Trussell, 2009)
If the BBT has risen and has stayed higher for 3 full days, ovulation has occurred and the fertile period has passed. Sex can resume on the 4th day until her next monthly bleeding.