DOR stands for diminished ovarian reserve, a condition where a woman has fewer eggs remaining in her ovaries than expected for her age. It’s one of the most common diagnoses in fertility medicine and a frequent reason why conception takes longer or requires assistance. Having DOR doesn’t mean you can’t get pregnant, but it does signal that the window for using your own eggs may be narrower than average.
What Ovarian Reserve Actually Means
Every woman is born with a fixed number of eggs. Unlike sperm, which are produced continuously, eggs can’t be regenerated. From puberty onward, that supply steadily declines. Ovarian reserve is simply a measure of how many eggs remain at any given point. A key hormone involved in this process, anti-Müllerian hormone (AMH), drops by roughly 5% per year during a woman’s 30s.
DOR is not a permanent diagnosis but rather a snapshot. It sits on a spectrum between normal fertility and a more advanced condition called primary ovarian insufficiency (POI), where periods stop entirely before age 40 and hormone levels reach menopausal ranges. Women with DOR still have regular menstrual cycles and their hormone levels, while abnormal, haven’t crossed into menopausal territory. The American Society for Reproductive Medicine considers DOR and POI distinct conditions, and there’s no clear evidence that DOR inevitably progresses to POI.
Causes of Diminished Ovarian Reserve
The most common cause is simply age. Every woman’s ovarian reserve declines over time, and DOR in the mid-40s is a normal part of reproductive aging. When it occurs earlier, something else is typically accelerating the process.
Known causes and risk factors include:
- Genetic factors: The strongest genetic link is to the FMR1 gene, the same gene associated with Fragile X syndrome. Women who carry certain variations of this gene tend to show signs of premature ovarian aging, including shorter menstrual cycles and hormonal shifts. Other gene variations affecting egg development and hormone receptors have also been linked to DOR.
- Cancer treatment: Chemotherapy and radiation can directly damage the egg supply, sometimes severely. Ovarian surgery for cysts or endometriosis also reduces the number of remaining eggs.
- Autoimmune conditions: In some cases, the immune system targets ovarian tissue, speeding up egg loss.
- Environmental exposures: Animal studies suggest that toxins like certain pesticides and industrial chemicals may damage the egg supply through changes in how genes are expressed, without altering DNA itself. Whether this translates directly to humans isn’t fully proven, but it’s a plausible concern.
- Family history: Women whose mothers or sisters went through early menopause face a higher risk of DOR.
In many cases, no clear cause is found. These are classified as idiopathic, meaning the decline is real but unexplained.
Symptoms and How DOR Is Found
Most women with DOR have no obvious symptoms. The most common way it’s discovered is through fertility testing after months or years of trying to conceive without success. Some women notice their menstrual cycles getting consistently shorter, which can reflect a shortened first half of the cycle as the ovaries work harder to mature an egg. If DOR is more advanced and approaching insufficiency, perimenopause-like symptoms such as hot flashes, irregular periods, and vaginal dryness can appear.
How DOR Is Diagnosed
Diagnosis relies on a combination of blood tests and ultrasound, typically performed on day 2 or 3 of the menstrual cycle.
- AMH (anti-Müllerian hormone): This blood test reflects the size of the remaining egg pool. A normal range is roughly 1.0 to 4.0 ng/mL. Values below 1.0 ng/mL raise concern for diminished reserve.
- FSH (follicle-stimulating hormone): FSH is the hormone your brain sends to the ovaries to stimulate egg development. When fewer eggs remain, the brain compensates by sending more FSH. A normal range is about 1.4 to 9.9 IU/L. Elevated levels, particularly above 10, suggest the ovaries are working harder than expected.
- AFC (antral follicle count): An ultrasound counts the small follicles (2 to 10 mm) visible on both ovaries early in the cycle. A lower count corresponds to a smaller egg supply.
No single test is definitive. Fertility specialists typically look at all three together to get a complete picture. AMH is considered the most reliable because it stays relatively stable throughout the menstrual cycle, while FSH can fluctuate month to month.
Can You Still Get Pregnant With DOR?
Yes, and this is one of the most important things to understand. DOR measures egg quantity, not egg quality. A woman with fewer eggs can still have eggs that are perfectly capable of fertilization and healthy pregnancy, especially if she’s younger.
A study of women under 35 with low AMH levels found that clinical pregnancy rates through timed intercourse (with or without mild ovulation-boosting medication) were 41.3% for those with low AMH and 27.6% for those with very low AMH, compared to 43.9% in the normal group. The difference wasn’t statistically significant for the low AMH group, suggesting that younger women with mildly reduced reserve still have reasonable chances naturally. However, the cumulative live birth rate over 18 months dropped more notably in the very low AMH group (20.0% versus 55.9% in the normal group). The takeaway: age matters enormously alongside reserve numbers.
For women over 40, the picture changes. Live birth rates per IVF cycle range from about 4.7% to 9.7% using their own eggs. At that point, both quantity and quality are typically declining together.
Treatment Approaches
Treatment for DOR focuses on making the most of the eggs that remain. There’s no way to increase the total number of eggs, but there are strategies to improve how the body responds to stimulation and to optimize the quality of eggs that are retrieved.
Fertility Treatment Protocols
Standard IVF protocols sometimes suppress the ovaries too aggressively for women with DOR, resulting in a poor response. Fertility clinics have developed several modified approaches. The microdose flare protocol uses a much smaller dose of medication to trigger the body’s own hormonal surge before stimulation, taking advantage of that natural boost rather than suppressing it. Antagonist protocols take a different approach, adding a blocking medication only once follicles reach a certain size, which avoids suppressing the ovaries during the critical early recruitment phase. Some clinics also use short protocols or begin stimulation earlier in the cycle to capture as many developing follicles as possible.
Pretreatment with oral contraceptives for one cycle before stimulation can help synchronize follicle development, potentially improving the response. Your fertility specialist will select and adjust protocols based on how your ovaries respond, and it’s common to try different approaches across cycles.
Supplements That May Help
Two supplements have the strongest evidence for DOR: DHEA and CoQ10.
DHEA, a hormone precursor typically taken at 25 mg three times daily for 2 to 3 months before an IVF cycle, has been shown to improve the number of eggs retrieved and nearly double the rate of high-quality embryos compared to no supplementation. It also improved clinical pregnancy rates by about 92% in pooled clinical trial data.
CoQ10, an antioxidant that supports cellular energy production, showed similarly promising results at 200 mg three times daily for about 60 days before treatment. In a network analysis of multiple trials, CoQ10 was the single best intervention for improving live birth rates, more than doubling them compared to standard treatment alone. It also increased the number of eggs retrieved and improved clinical pregnancy rates.
These supplements appear to work by supporting the energy-intensive process of egg maturation. Eggs require enormous amounts of cellular energy to divide properly, and both DHEA and CoQ10 contribute to that process through different pathways.
Donor Eggs
When a woman’s own egg supply is extremely low or egg quality has declined significantly due to age, donor eggs offer substantially higher success rates. One study comparing outcomes found that each donor egg had a 6.8% chance of resulting in a live birth, compared to 1% per egg in women over 40 using their own. Donor eggs bypass the ovarian reserve issue entirely, since the eggs come from a younger donor with a full supply.
DOR vs. Primary Ovarian Insufficiency
These two conditions are often confused, but they’re clinically distinct. DOR means reduced but still functional ovarian reserve with regular periods. POI (also called premature ovarian failure) means FSH levels have reached menopausal levels (above 40 IU/L), periods have been absent for at least four months, and the woman is under 40. A woman in her early 40s can be diagnosed with DOR but would not meet criteria for POI. Think of DOR as the ovaries slowing down, while POI is the ovaries essentially shutting down prematurely.