What Is Diminishing Ovarian Reserve?

Medically Reviewed by Traci C. Johnson, MD on February 11, 2024
3 min read

Diminishing ovarian reserve (sometimes called diminished ovarian reserve or DOR), happens when one of your ovaries produces fewer eggs and eggs that are harder to fertilize. This affects your overall fertility and ability to get pregnant. Between 10% to 30% of people who seek help for infertility have this condition.

At birth, your ovaries already contain six million eggs. By puberty, that number drops to a few hundred thousand. Research shows that the likelihood of getting pregnant starts to fall around age 25. Between ages 25 and 40, fertility rates fall further. This is caused by the quality and quantity of your eggs decreasing as you get older.

Other factors that contribute to a diminishing ovarian reserve include:

  • Ovarian surgery, such as that from endometriosis
  • Smoking
  • Genetic abnormalities
  • Aggressive medical treatments, such as radiation to treat cancer

In some cases, DOR has no known cause.

As egg production and viability drop, some women may notice as they get older and diminishing ovarian reserve continues that the time between their menstrual cycles becomes shorter.

As women eventually approach menopause, when they will no longer be able to get pregnant.

The only way to know for sure if you have a diminishing ovarian reserve is to do an ovarian reserve test. Ovarian reserve testing includes both blood tests and ultrasound to measure the size of your ovarian egg pool. It’s important to note that while these tests are important for diagnosing DOR, no ovarian reserve test is absolutely accurate when it comes to predicting whether or not you can become pregnant.

Blood tests. The most common way to test your ovarian reserve is by measuring certain hormone levels in your blood. Two of these hormones, estradiol and follicle-stimulating hormone (FSH), are checked at the beginning of your cycle, usually on the third day. The AMH blood test measures levels of anti-mullerian hormone, which corresponds to your egg count. It can't predict your fertility, however.  

Typically, women who have higher levels of these hormones around the third day of their cycle are less likely to have a baby either through hormonal treatments to stimulate ovulation or in vitro fertilization (IVF) compared to women in the same age group who don’t have diminished ovarian reserve.

Another ovarian reserve test is to see how your ovaries respond to a medication called clomiphene citrate. To do this test, your doctor will give you the medicine at the beginning of your cycle after your estradiol and FSH levels are measured. Your doctor will measure your levels again after taking clomiphene citrate to see if it has an effect.

Ultrasound. Your doctor may recommend a transvaginal ultrasound at the beginning of your cycle. This is to measure the number of antral follicles between 2 and 10 millimeters in both of your ovaries. The follicles are pockets inside your ovaries that are full of fluid and contain one egg each. The follicle count lets your doctor know how many eggs are available.

At the moment, there’s no known way to slow down your ovaries from aging or losing normal function. However, your doctor can use common low ovarian reserve treatments to help with the conception process.

Preservation. Once your doctor diagnoses your diminishing ovarian reserve, they might suggest preserving your eggs for a future pregnancy. To do so, your doctor will take out eggs from your ovaries and freeze them. The younger you are, the more success you will typically have with this procedure.

Donor eggs and IVF. If you’re trying IVF, your doctor will probably give you high doses of hormones that will help to stimulate your ovaries. If this doesn’t work, your doctor will recommend using donor eggs. These eggs are usually donated by young women in their 20s. By using donor eggs, women with diminished ovarian reserve have higher chances of a successful pregnancy.