Basal Body Temperature Method

To use this method, the woman must take her basal body temperature (BBT) each morning before getting out of bed using a BBT thermometer that records in tenths of a degree and record it on a temperature graph. After 3-4 months a woman should be able to predict when she is ovulating based on the fact that the temperature drops just prior to ovulation and rises and remains elevated for several days after.

The temperature rises in response to increased progesterone levels that occur in the second half of the cycle.  Couples must avoid intercourse on the day of the temperature rise and 3 days after. Because the temperature rise does not occur until after ovulation, sex just prior to the rise increases the risk of pregnancy. Some couples abstain for several days before the anticipated time of ovulation and 3 days after.

Basal Body Temperature chart