By Alex Robles MD / February 7, 2023
Are you starting an estrogen priming protocol before an in vitro fertilization cycle?
Do you want to know why we do it?
This article will provide an overview of
Let’s get started.
Estrogen priming is the process of using estrogen pills in the preceding cycle before your IVF cycle to prepare your ovaries for stimulation.
The hope is that estrogen priming helps you respond better to IVF stimulation and have a more successful cycle.
Estrogen priming may enhance IVF stimulation by synchronizing the growth of your follicles.
You see, the goal of an IVF cycle is to grow multiple follicles so that we can collect as many eggs as possible during the egg retrieval procedure.
However, not every follicle grows at the same rate.
In addition, it is possible for you to have a larger follicle already growing before the stimulation phase begins.
In theory, priming the ovaries with estrogen may help prevent uneven growth of your follicles.
Estrogen priming can also be beneficial for patients who had a poor response in a previous IVF cycle.
More on that later.
The benefit of having your follicles grow at similar rates is that it can increase the chance of obtaining the highest number of mature oocytes (eggs).
The bigger the follicle (~16-22 mm), the more likely we will retrieve a mature egg from it.
In an ideal world, all of your follicles would reach 16-22 mm at the same time, rather than having one or two follicles leading the others by a large margin.
There is only so much time you can give the smaller follicles to catch up once you have two or more follicles above 18 mm.
Estrogen priming is typically done for about seven days before the start of controlled ovarian stimulation (the IVF cycle).
Before starting the pills, we need to wait until you are in the correct stage of your menstrual cycle (the luteal phase).
Some reproductive endocrinologists prefer to see you in the office to do an ultrasound and bloodwork first. This appointment ensures that you have ovulated and are in the luteal phase.
Other doctors feel comfortable having you start the medication seven days before your anticipated menstrual cycle.
One last option is using ovulation predictor kits.
ovulation on day 14, and luteal phase from days 15 to 28- also shows the hormones that are rising at each point" width="560" height="315" />
An ovulation predictor kit (OPK) is another helpful tool to help you time your estrogen priming.
The OPK measures the luteinizing hormone (LH) in your urine, which will surge ~24 hours before you ovulate.
Start testing the OPK ~10 days after the start of your menstrual cycle. Most women will have a positive test on days 12-14. Once you get a positive test, wait exactly one week to ensure you are in the late luteal phase.
After the week, begin the estrogen pills until you get your next bleed.
Here is an example of the calendar for an estrogen priming protocol.
The recommended dose of estrogen for priming is 2 mg twice a day. You could also use an estrogen patch to get the same effect.
*Note: Estrogen priming is not the same as birth control pills.
The most common side effects of estrogen medication include
However, these side effects are usually mild and will dissipate after a few days.
Most patients don’t experience any side effects at all.
Unfortunately, estrogen priming does not improve egg or embryo quality.
As far as we know, there are no concrete strategies to improve egg quality.
The best thing that you can do is to live a healthy lifestyle which includes:
Estrogen priming does not reduce the number of antral follicles you have at the start of an IVF cycle.
It does, however, prevent follicles from growing. This is how it works to synchronize follicular growth during controlled ovarian stimulation.
Estrogen priming may also be helpful for patients who have had a poor response to IVF treatment (aka, a poor responder).
Poor responders often have diminished ovarian reserve (DOR) and elevated levels of follicle-stimulating hormone (FSH).
This is problematic because FSH is the primary hormone we use to stimulate your ovarian follicles.
If your ovaries are already exposed to high levels of follicle-stimulating hormone, they are much less likely to respond to additional FSH injections.
In these cases, estrogen priming may improve ovarian responsiveness to the medications by reducing the levels of FSH in the body before the stim.
The data looks promising, but the clinical trials are not recent.
For example, a 2012 retrospective study of 155 poor responders found that patients who received luteal estradiol had a lower cycle cancellation rate and a higher number of oocytes at the egg retrieval than the control group. There was also a trend toward better fertilization rates, but those data did not reach statistical significance.
Other smaller studies had similar findings.
Based on the available literature, estrogen priming may improve clinical pregnancy rates in poor responders.
A systematic review and meta-analysis of eight studies found that estrogen priming improved clinical pregnancy rates by 33%.
However, this study is from 2013 and has a relatively small sample size. More research is needed.
We can use estrogen priming with any ovarian stimulation protocol. The most common IVF protocols include
Luteal phase estradiol can be a useful tool for improving the follicular response in an ovarian stimulation cycle. Studies show that it can help synchronize follicular growth and reduce FSH levels in low responders.
However, more research is needed to determine if it can improve the clinical pregnancy or live birth rate.
Be sure to talk to your fertility doctor to learn if estrogen priming is right for you.
Make An Appointment With Dr. Robles To Discuss Your Fertility Options Today!
