The reason that temperatures don’t help determine the best time to achieve pregnancy is because by the time you have a temperature shift, the egg is usually already gone.

 

However, the temperature is still very useful for determining many things, including:

(1) whether you are ovulating at all

(2) whether the second phase of your cycle (from ovulation until your period) is long enough for your egg to implant

(3) whether you have gotten pregnant that cycle.