Progesterone starts to rise just before ovulation, toward the last week of the heat cycle. It is well established that as soon as the progesterone levels are around 2 ng/mL, luteinising hormone peaks and ovulation takes place when the progesterone levels are around 5–8 ng/mL. From this point, eggs require 48 hours to mature, and by that time the progesterone levels usually average 10 ng/mL or above. Find out more here
