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Ask Dr. Marc.....What is Estrace priming?

By on July 22, 2013

This question and answer was originally published on the blog clomidandcabranet.com  by Katie: "Infertility Warrior, Mommy to two, wife of rock and roller, Child and Adolescent Psychotherapist , and Parenting Expert in Los Angeles, CA"

Dear Dr. Marc

I'm currently on estrace 2mg twice daily as part of an estrace priming protocol for in-vitro fertilization.  My FSH went from 6.7 in 2010 to 17 last month (wah).  Even though I've done this, gotten pregnant and have a gorgeous little girl I am still nervous as hell to do this again.  I don't know much about estrace priming, can't seem to find any good info on it and am wondering if anyone else has done it and maybe Dr. Marc can comment.  I know it's for women with diminished ovarian reserve, like me, but not sure the rationale (even though I'm a pharmacist - a DOCTOR of pharmacy - I become very dumb when it comes to hormones and infertility and endocrinology).

Hi Estrace priming,

It is amazing how years of training can disappear in an instant, once a clinical situation become personal! 

The rationale behind estrace priming is based on sound physiology in and works quite nicely for some patients.  The bottom line is that the estrogen prevents your body from recruiting follicles too early (a common problem as ovarian reserve declines).  By limiting early recruitment, there are more follicles available at the beginning of your cycle.  Additionally, the follicles tend to grow together in a more synchronized manner.  Ultimately the goal is that the eggs will all be ready at the same time and hopefully result in more high quality embryos. 

To explain it with a little more detail, you need to understand that there are several hormones which participate in the communication between your brain and ovary (as my 7th grade health class teacher famously said “hormones are the words of the body”).  These include estrogen, FSH, LH and inhibin amongst many others.  Inhibin is an often overlooked hormone which suppresses (or inhibitits) the release of FSH from your brain during the last week of the cycle (FSH is the chief hormone responsible for making your eggs “grow”).  As ovarian reserve declines, the production of inhibin in that last week of the cycle also declines.  This decline allows your brain to start releasing FSH earlier than it normally would.  The FSH then stimulates the ovary in the last week of the preceding cycle, and by the time the third day of the next cycle comes around, there is already a follicle or 2 which is bigger than the rest.  We call this dys-synchrony and it is one of the reasons, of lower egg yield in low responders. 

With estrace priming, the estrogen pills, which also suppress FSH release, essentially replace the inhibin.  Theoretically, if the estrogen suppresses FSH, then the follicles should all be the same size when your period begins.  If the follicles are all the same size when stimulation begins, there is a better chance that they will grow at the same rate and be ready at the same time for the egg retrieval

I hope that is clear.  If not, rest assured that estrace priming is a safe and relatively effective technique which can help with egg yield.  If you have any other questions, feel free to contact me.

Good Luck,

Dr. Marc 

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