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What is Ovarian Reserve?

Fertility - January 31, 2020

When you start talking about fertility (or the lack of it), the term ovarian reserve gets mentioned a lot.  It’s pretty important, and yet many women don’t really understand what it is, how we measure ovarian reserve, and what it really means about your likelihood of having a baby.

Ovarian reserve is a term used to describe the ability of the ovaries to provide egg cells that are capable of fertilization and that will result in a healthy and successful pregnancy. In other words:  your egg supply. You’ve heard of the Federal Reserve? Well, ovarian reserve is pretty much the same thing if eggs were kept in bank accounts. Turns out, a woman’s ovarian reserve is actually at its peak before she’s even born!  Female embryos 6 months in age have their lifetime maximum ovarian reserve. From this point on, it’s on the decline. Ovarian reserve takes another big hit just before birth, nose diving from 7 million potential eggs to around 2 million, but that’s still more than enough eggs to get the job done.

According to the American College of Obstetricians and Gynecologists, these are the average number of eggs women have at each stage of life: 

  • 20 Weeks of Gestation: 6 to 7 million oocytes 
  • Birth: 1 to 2 million oocytes
  • Puberty: 300,000 to 500,000 oocytes
  • Around age 37: roughly 25,000 oocytes
  • Around age 51 (the average age of menopause in the U.S.): approximately 1,000 oocytes

By measuring your ovarian reserve, we are essentially assessing your fertility potential. How do we do this? There are a couple of easy tests that are good predictors, and they are sometimes used in tandem for better accuracy. 

The AMH Test:

A common blood test used by reproductive endocrinologists (REs) is the Anti-Müllerian Hormone (or AMH) test.  AMH is a hormone that’s produced by the cells inside a woman’s follicles—the round, cellular structures in the ovaries that contain eggs. Eggs mature inside the follicle until they are eventually mature enough to be released during ovulation.  Therefore, the number of follicles a woman has directly correlates to the number of eggs “on deck”, and the level of AMH created by these follicles reflects that reserve.

“We look for patients to have an AMH level of greater than 2.5 ng/mL.  At this level, we see greater egg production and a better potential for fertility.  Levels less than 0.2-0.5 nd/mL are commonly associated with an increased likelihood of challenges conceiving, including cancelled IVF cycles, poor response to stimulation medications, and fewer eggs retrieved from the ovaries,” shares reproductive endocrinologist Dr. Rob Kiltz, Founder and Director at CNY Fertility and CNY Preserve. 

But Dr. Kiltz cautions that lower AMH levels are just a piece of the overall fertility picture and not a guarantee of failure or success. “AMH just gives us a better sense of what the playing field looks like and how much time is left in the game. I’ve seen clients get pregnant with IVF even with an undetectable AMH.”

AMH does not tend to fluctuate much throughout the month, so it can be tested on any day of the cycle whether you’re on birth control pills or even pregnant. But it can be affected by age, obesity, whether you’ve had radiation or chemotherapy, if you’ve had ovarian surgery, and if you have Polycystic Ovarian Syndrome (PCOS).

FSH Test:

We can also test a woman’s FSH or Follicle-Stimulating Hormone level. FSH helps to mature the ovarian follicles that release the eggs. Without the release of FSH, a woman cannot continue her reproductive cycle, as her ovaries will not release an egg. Unlike AMH, FSH levels do vary throughout a women’s cycle and over time. FSH levels naturally rise as women get older. Lower FSH levels are generally associated with better ovarian function, while higher FSH levels are associated with low ovarian reserve.

REs usually test FSH levels on Day 3 of your cycle along with Estradiol (E2). FSH levels vary significantly from woman to woman depending on age. Normal FSH levels go from below 7.0 mIU/mL for someone younger than 33 to over 8.5 mIU/mL for a woman over 41. FSH levels continue to rise, until they reach a level of 40 mIU/mL or higher, at which point, a woman would be considered in menopause.

Antral Follicle Count:

A third test REs sometimes use to predict ovarian reserve is an antral follicle count (ARC).  Antral follicles are the small follicles (about 2-9 mm in diameter) that can be seen via ultrasound. Antral follicles are also called resting follicles. Usually performed between Days 2 and 5, a transvaginal ultrasound is used to look at each ovary and actually count the number of follicles that measure between 2 and 10 mm. We will generally be looking for anywhere between 14-35 total antral follicles. Anything in this range would be considered “normal” with a likely good response to stimulation meds (if needed) and very good chances for IVF success.

Again, ARC in and of itself is not a perfect test, and results can be somewhat subjective. Different ultrasound technicians can sometimes get differing counts depending on what they observe and their training. 

Diminished Ovarian Reserve (DOR):

Should test results come back that suggest low ovarian reserve, patients may be diagnosed with Diminished Ovarian Reserve (DOR).  While those with diminished ovarian reserve have fewer eggs than those of a similar age without a DOR diagnosis, there’s no clear consensus on the average number of eggs for those with the condition.

As previously noted, aging naturally reduces your egg reserves, but there are a number of other factors that can speed up this decline, including:  endometriosis, tubal disease, prior ovarian surgery, pelvic infection, chemotherapy/radiation, smoking, autoimmune disorders, illness such as mumps, and genetic abnormalities such as Fragile X Syndrome.  And sometimes doctors can find no apparent cause for a woman’s DOR.

DOR can be a discouraging diagnosis, but women should take heart that it is still very possible to get pregnant with DOR using your own or donor eggs.  Early diagnosis generally improves a woman’s chances of conceiving. Taking a supplement of DHEA (dehydroepiandrosterone) is also believed to increase fertility. 

Also, ovarian reserve is a reflection of the quantity of eggs still available, not the quality. REs have no way to assess overall egg quality, however we do know that egg quality begins to decline as women age. Older eggs are more likely to experience errors during the division process just prior to ovulation making it more likely that they’ll contain abnormal chromosomes. This explains why the chances of Down Syndrome and other abnormalities increase as women age. 

Can I Increase My Ovarian Reserve?

Unfortunately, there’s no way to increase your ovarian reserve. Once your eggs are gone, they are gone.  Genetics, age, and overall health all play somewhat of a role, but there is nothing you can do to stop the inevitable loss of eggs every month. Women can, however, focus on improving their egg quality and overall health and wellness by eating a high fat/low carb diet, reducing inflammation and stress, and following an egg enhancement protocol.

Assess Your Fertility Today!

While all of these tests do provide important information when evaluating ovarian reserve, they all have limitations, and none of the results categorically confirms whether a woman can conceive or not.

For an even better picture, CNY Preserve recommends a full fertility workup, which includes:  an AMH test, FSH test, E2 level, medical history, and ultrasound.

Have questions about your fertility and want to know your options?  CNY Preserve is ready to explore your possibilities. Schedule your consultation today or give us a call 833-CNY-PRES. We’re here to provide the support and resources you need on your fertility journey.

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