FSH and Estradiol(Estrogen)

It is also important to measure the estradiol on day 3. Day 2 is fine. The reason its day 3 is 15-20 years ago, the IVF medications were always started on day 3. So everyone who started an IVF cycle had Estradiol and FSH measured on day 3. Pregnancy rates were checked against different levels of FSH and Estradiol, and that’s how the original work was done. I did research with the day 3 Estradiol level when I was a fellow.
If the estradiol level is high, the FSH level will be artificially lowered, and the FSH level will therefore not accurate. For example, I may have a patient with an FSH an 18 and an
estradiol level of 45. Next month the FSH is 8, but the Estradiol is 92. This is just as bad as her first test. Once the estradiol is over about 50, the FSH will be lowered. Just because the FSH becomes lower does not mean the patient is more fertile. If the estradiol is elevated month to month, this is as bad as the FSH being elevated month to month.
Why does the Estardiol level become elevated? For some women, the cycle gets shorter as their ovaries age. So that by day 3, when the follicle should not yet be growing, the follicle has already started to grow and produce estradiol, and for reasons we don’t yet understand, this is bad. Taking estrogen pills to lower the FSH level does not help. It’s like taking Tylenol to lower your temperature if you have appendicitis. Your temperature may come down, but there is still a problem. Some doctors say there is a benefit to lowering the FSH level with estrogen. They say that when the FSH is high, the ovary become resistant to FSH and can't be stimulated by fertility drugs(which contain FSH). The theory is that by lowering FSH levels with estrogen, the ovary will respond when high doses of FSH are added(in the form of the fertility injections). It sounds reasonable, however there is no literature to support these claims, i.e. there is no evidenced based medicine