For the correct measurement of our hormones throughout the cycle, we must understand that the sample must be taken at the right time for each hormone. This is because our female sex hormone levels fluctuate throughout the cycle. Therefore, for the measurement of prolactin, estradiol, LH and FSH, we should take our sample between days 3 and 5 of our menstrual cycle. Whereas, for progesterone measurement, you should take your sample 7 to 9 days before your next cycle.