Diminished ovarian reserve (DOR) means the ovaries contain fewer eggs than expected for your age. It’s not the same as menopause or infertility, but it does signal that the pool of eggs available for conception is lower than normal, which can make getting pregnant harder and narrows the window for fertility treatment. DOR is diagnosed through blood tests and ultrasound, and it affects women across a wide age range.
How Ovarian Reserve Works
Your ovarian reserve is the total number of eggs stored in your ovaries at any given time. You’re born with all the eggs you’ll ever have, roughly one to two million. That number declines steadily through life as eggs are either ovulated or naturally reabsorbed by the body. By puberty, the count is already down to around 300,000 to 400,000. This gradual loss is completely normal.
Each month, a group of immature follicles (tiny fluid-filled sacs that each contain an egg) are recruited to begin developing. Typically only one matures enough to ovulate. The rest are lost. In women with DOR, the remaining pool of recruitable follicles is significantly smaller than what’s typical for their age. The ovaries still function and still produce hormones, but they have less raw material to work with.
How DOR Is Diagnosed
Two blood tests and one ultrasound measurement form the core of a DOR diagnosis.
Anti-Müllerian hormone (AMH) is produced by developing follicles and gives the most direct snapshot of how many eggs remain. An AMH below 1.2 ng/mL is the widely used threshold for diminished reserve. A large study of nearly 23,000 women found that by age 30, about 24% of women already fall below this cutoff. By 35, nearly half do. By 40, roughly 73% have AMH levels under 1.2 ng/mL. The median AMH at age 25 is 3.3 ng/mL; by 36, it drops to 1.1 ng/mL.
Follicle-stimulating hormone (FSH) is measured on day 2, 3, or 4 of your menstrual cycle. When the egg supply dwindles, the brain compensates by pumping out more FSH to push the ovaries harder. Elevated early-cycle FSH is a hallmark of DOR, though the exact cutoff varies slightly between clinics.
Antral follicle count (AFC) uses a transvaginal ultrasound to count the small follicles visible in both ovaries early in your cycle. A low count supports the diagnosis. Together, AMH, FSH, and AFC give a reliable picture of where your reserve stands relative to other women your age.
DOR vs. Premature Ovarian Insufficiency
These two conditions sit on a spectrum but are clinically distinct. With DOR, you still have regular periods and your FSH is elevated but not at menopausal levels. With premature ovarian insufficiency (POI), periods have stopped for four or more months, FSH rises above 40 IU/L (a postmenopausal level), and the diagnosis applies only to women under 40. Think of DOR as an earlier, less severe point on the same continuum. Women with DOR may still conceive naturally or respond to fertility treatment, while POI represents a more advanced stage of ovarian decline.
Women in their early 40s can be diagnosed with DOR but would not qualify for a POI diagnosis, since POI by definition occurs before age 40.
What Causes It
Most of the time, DOR is simply the result of normal aging. Egg quantity and quality both decline with time, and some women start with a smaller reserve or lose eggs faster than average for reasons that aren’t fully understood. The exact mechanisms behind accelerated egg loss remain unclear, but several known risk factors speed up the process:
- Genetic conditions affecting the X chromosome, including Fragile X premutation carriers, are at higher risk.
- Cancer treatment with chemotherapy or pelvic radiation can damage or destroy follicles.
- Ovarian surgery to remove cysts or endometriosis tissue reduces the physical amount of ovarian tissue available.
- Autoimmune conditions can cause the immune system to attack ovarian tissue.
- Loss of an ovary cuts the total reserve roughly in half.
In many cases, no specific cause is ever identified. A woman in her late 20s or early 30s may discover she has the ovarian reserve of someone a decade older, with no clear explanation why.
Signs You Might Notice
DOR often has no obvious symptoms, which is why it frequently comes as a surprise during fertility testing. The most consistent early sign is a shorter menstrual cycle. A systematic review found that women with cycles of 21 to 27 days had significantly lower AMH levels, about 1.3 ng/mL lower on average, compared to women with cycles of 28 to 31 days. Shorter cycles were also linked to 19% lower odds of conceiving naturally in any given month and 24% lower clinical pregnancy rates with IVF.
If your period has been gradually arriving a few days earlier than it used to, that shift may reflect a shortened follicular phase, the first half of the cycle when an egg matures. As the ovary has fewer follicles to choose from, this phase compresses. It’s a subtle change that most women attribute to normal variation, but it can be an early biomarker of declining reserve.
How DOR Affects Fertility
A lower egg count doesn’t mean zero chance of pregnancy, but it does reduce the odds in two ways. First, fewer eggs are available each cycle, so the monthly probability of conception drops. Second, because DOR often correlates with egg quality decline (especially in older women), the eggs that do develop may be less likely to result in a healthy pregnancy.
During IVF, women with shorter cycles and lower reserve produce fewer eggs per retrieval, about 1.8 fewer on average compared to women with normal-length cycles. Fewer eggs means fewer embryos to choose from, which generally translates to lower cumulative success rates per treatment cycle. That said, it only takes one good egg. Many women with DOR do conceive, sometimes naturally and sometimes with assistance.
Fertility Treatment Options
Standard IVF protocols that suppress the ovaries before stimulation tend to work poorly for women with DOR because there’s already a limited supply. Suppressing the ovaries further leaves even less to work with. Fertility specialists have developed modified approaches to address this.
Microdose flare protocols and short-flare protocols use smaller, faster-acting medication to stimulate follicle growth without the deep suppression phase. Another approach, luteal estradiol priming, starts estrogen supplementation in the second half of the cycle before stimulation begins. Studies show this reduces the chance of a cancelled cycle and improves clinical pregnancy rates, though it doesn’t necessarily increase the number of eggs retrieved. The goal with all of these strategies is to coax the most out of whatever follicles remain.
Some women with very low reserve opt for multiple retrieval cycles, banking embryos over time to improve their odds before attempting a transfer.
Supplements That May Help
Two supplements have the strongest evidence for improving outcomes in women with DOR undergoing IVF. A network meta-analysis of randomized controlled trials found that CoQ10, an antioxidant involved in cellular energy production, more than doubled the odds of clinical pregnancy compared to standard treatment alone. It also showed the highest probability of improving live birth rates among all adjunct therapies studied, with roughly 2.4 times the odds of a live birth.
DHEA, a hormone precursor naturally produced by the adrenal glands, improved clinical pregnancy rates by about 1.9 times, increased the number of eggs retrieved, and nearly tripled embryo implantation rates. Growth hormone also showed benefits but ranked behind both CoQ10 and DHEA in most outcome measures. These supplements are typically started several weeks to months before an IVF cycle to allow time for developing follicles to benefit, since eggs take about three months to mature from their dormant state.
What a DOR Diagnosis Means Long Term
DOR is not a fixed sentence. It describes where your ovarian reserve stands right now, not whether pregnancy is possible. Some women with low AMH conceive without any intervention. Others pursue IVF or consider using donor eggs. The diagnosis does mean that time is a more pressing factor than it would be otherwise, since the reserve will continue to decline.
If you’re not ready to try for a pregnancy right away, egg or embryo freezing preserves options while your current reserve is at its highest point. The younger the eggs at the time of freezing, the better their quality tends to be, so earlier action generally offers more flexibility later.