What is Estradiol?
Estradiol is made by the egg follicles as they grow in the ovary. Estradiol, in addition to progesterone, prepares the uterine lining to receive the fertilized egg.

When is the Estradiol test done?
The blood test to measure estradiol is taken at the same time as the FSH level on day 2 or 3 of your cycle.

An estradiol level less than 80 on day 2 or 3 of your cycle indicates that pregnancy is possible.

A high estradiol level (greater than 80) shows that egg quality (ovarian reserve) is poor and a successful pregnancy is unlikely.