Diminished Ovarian Reserve (DOR)

Last updated: November 9, 2023

What Does Diminished Ovarian Reserve (DOR) Mean?

Diminished ovarian reserve (DOR) is a condition of reduced fertility where the number of high-quality eggs in a women’s ovaries starts to decline. This decline can reflect a low number of follicles or impaired maturation of follicles. This leads to a decrease in the number of healthy eggs available for fertilization and impacts the ability to conceive.

Diminished ovarian reserve is also known as the poor ovarian reserve, declining ovarian reserve, or impaired ovarian reserve.

FertilitySmarts Explains Diminished Ovarian Reserve (DOR)

Ovarian reserve refers to the number and quality of eggs that a woman has remaining. It is understood to be an indicator of potential fertility. During each monthly cycle, typically one follicle reaches maturity and is released by the ovaries through ovulation. It is expected that the reserve of eggs naturally decreases as women age:

  • Women are born with around 2,000,000 eggs
  • At the start of puberty, most women have around 400,000 eggs
  • During their late 30s, most have around 27,000 eggs
  • At the onset of menopause, most women have around 1,000 eggs

Factors contributing to DOR include:

  • Advanced reproductive age, specifically over the age of 40
  • Trauma to the ovaries
  • Endometriosis impacting the ovaries
  • Pelvic inflammatory disease (PID)
  • Previous chemotherapy or radiation

Some women will experience a shortened menstrual cycle lasting from 25 -28 days which may indicate DOR, but most women require ovarian reserve testing for diagnosis. Diagnosis is based on:

  • Elevated levels of follicle-stimulating Hormone (FSH) and estradiol
  • Decreased levels of antral follicles seen on transvaginal ultrasound
  • Low levels of the anti-mullerian hormone

There are presently no treatments available to slow down or reverse ovarian aging, but fertility preservation may be possible. Freezing eggs for future use is a possibility, but the best time to freeze eggs is when women are younger.

Women with DOR face the same reduced success of conceiving through in vitro fertilization (IVF) as they do when attempting to conceive naturally. Additionally, chances of miscarriage are increased due to lower egg quality.

The use of donor eggs is also a possibility for women with DOR.


Poor Ovarian Reserve

Declining Ovarian Reserve

Impaired Ovarian Reserve

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