The best time to perform an estrogen test is recommended on the 2nd-3rd day of menstruation. If you have a heavy period on the second day of your period, the estrogen test can be performed on the second day of your period. If your menstrual flow is low on the second day of your period, it is recommended that you have an estrogen test on the third day when your period is heavy. The estrogen test should not be performed after the 5th day of menstruation. If the test is performed after the 5th day of menstruation, the results may be affected. The estrogen test should be performed on an empty stomach, preferably between 9 and 10 am, and no strenuous exercise should be performed before the estrogen test to avoid affecting the accuracy of the test results. The main purpose of estrogen test is to understand women’s endocrine secretion, which can affect menstruation and conception.