Low ovarian reserve

Low ovarian reserve is when there is a physiological decrease in the number of eggs, resulting in an insufficient number to ensure a reasonable chance of pregnancy. This only becomes an issue when a woman has problems getting pregnant. Other women experience this condition in their 30’s and 40’s. 

“Ovarian reserve” refers to the number and quality of the eggs in a person’s ovaries. To have a low ovarian reserve, or a diminished ovarian reserve, is to have fewer eggs of a lower quality than would normally be expected for a patient of a certain age.

The average amount of eggs in your body will normally depend on how old you are. Every person with ovaries has had their egg supply from birth, with all the eggs they will ever have. This number then decreases over time, as they age and as they lose eggs through periods or use them through pregnancy. The American College of Obstetricians and Gynecologists has even recorded the average number of oocytes (eggs) a person should have at various ages:

  • 20 weeks of gestation: 6 to 7 million 
  • Birth: 1 to 2 million
  • Puberty: 300,000 to 500,000
  • Around the age of 37: about 25,000
  • Around the age of 51 (the average age of menopause in the US): about 1,000

While it is clear that people with a low ovarian reserve have fewer eggs than those without, no one has established an average number of eggs available in those with the condition. This may be because the condition itself is generally defined by hormone levels, not by physically counting the number of eggs. 

The blood tests carried out to determine low ovarian reserve will measure follicle-stimulating hormone (FSH) and anti-Müllerian hormone (AMH) levels. Both of these hormones play an important role in menstruation and reproduction, particularly by helping to signal the ovaries to make oestrogen in the case of FSH.

Over time, a person’s FSH levels will increase and their AMH levels will drop. As such, assessing these against a baseline of a patient’s age can allow specialists to estimate ovarian reserve. Those with a low ovarian reserve should be seen to have particularly high levels of FSH and lower levels of AMH when these are both measured against their age.

Even though the low ovarian reserve is often noted as a cause of infertility, this does not mean that a person cannot get pregnant if they have the condition. If diagnosed early and treatment is carried out, most likely through medication, people with a low ovarian reserve can achieve a successful pregnancy. 

Specialists may also suggest freezing eggs for future use if a patient is not planning on trying for a baby for some time, or trying a cycle of IVF if they would like to begin right away.