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Ovarian reserve in simple terms means the number of eggs remaining in the ovary. As a woman grows older, she would naturally lose her egg reserve. This natural loss in the number of eggs expedites after the age of 35 years. So in women over 35 years of age is it normal to see low ovarian reserve.
However, often we see low ovarian reserve in younger women (<35 years of age). This article describes why ovarian reserve is low in some younger women and what it means to their fertility.
Why egg reserve goes down with age:
To understand why a young woman (<35 years of age) may have low ovarian reserve, it is important to understand what it means by natural decline in the eggs reserve.
At birth any baby girl is born with around 1-2 million of eggs in her ovaries. These eggs continue to undergo reduction by nature throughout the childhood period and by the time of puberty at the age of 10-12 years; the eggs remaining in the ovaries are around 300,000 – 500,000.
During the next 35-40 years of life of the women when she starts to ovulate, 400-500 will be selected to ovulate and remaining will continue to undergo reduction by nature. At the time of menopause, few hundred to 1000 eggs remain in the ovaries.
The rate at which the eggs are lost varies between different individual and is guided partly by her genetic make up and partly by various other factors and drugs.
The quality of the eggs starts to decline from around 35-37 years of age. This decline in the quality of the eggs is due to age related genetic changes in the eggs and changes in the microenvironment of the ovaries where the eggs develop.
Why ovarian reserve can be low in a young woman?
Younger women (<35 years) with low ovarian reserve also follow a similar pattern of decrease in the egg numbers as above, but at an accelerated rate. It could be also be that some of these women are born with a smaller pool of eggs at birth.
The rate of loss in the eggs reserve can be accelerated by various factors like:
Genetic factors (a trend running in the family)
Endometriosis
Smoking
Obesity
Infection: pelvic inflammatory disease
Drugs like chemotherapy/radiotherapy
Various autoimmune factors
"Ovarian reserve is primarily determined by genetic make-up of an individual. Environmental, nutritional factors and in-utero environment also influence the egg reserve."
Does it mean that it will be difficult to conceive?
Low ovarian reserve in a young woman is not a cause of infertility in itself. So long she has a regular menstrual cycle (26 – 35 days), she is releasing an egg every month, no matter how many eggs are remaining in the ovary. Even though the egg reserve is reduced, the quality of eggs is preserved in young women and hence natural conception is possible.
However, if the periods start to become very short (<25 days) or irregular, then it means low ovarian reserve is to that extent that she is not releasing egg every month and hence chances of pregnancy can be reduced.
"Young woman with low ovarian reserve but with regular menstrual cycle retain good fertility."
Does it mean that it will lead to early menopause?
It is difficult to make prediction of the age of menopause from ovarian reserve markers due to variable rate of egg depletion in different individuals.
However, as the accelerated egg depletion continues, the end result is menstrual irregularity and early menopause. The risk of early menopause is 10-11%, according to a 10 year follow up study of women who had poor response in IVF.
"Egg reserve in women with low ovarian reserve will decline at an earlier age and they might enter into menopause earlier (though difficult to predict when exactly this will happen)"
Early menopause is associated with risk of cardiovascular disease and osteoporosis. Please seek advice from GP regarding hormone replacement therapy, once periods start to become irregular.
Do I need IVF?
Low ovarian reserve in a young woman, with regular menstrual cycles and no other obvious reason for infertility, is not an indication for IVF.
However, according to the American College of Obstetricians and Gynaecologists, it is reasonable to encourage a woman to attempt to conceive sooner rather than later if her ovarian reserves are diminished, as her window of opportunity to conceive might be shorter than anticipated.
"The window of opportunity to get pregnant is shorter."
Hence, if natural conception does not happen within 6 months, then it might be prudent to consider IVF sooner than later.
Is my IVF success reduced if I have low ovarian reserve?
The overall success/cycle are lower in women with low ovarian reserve than those with normal ovarian reserve as they produce less number of eggs and hence the odds of getting an embryo for transfer is lower with less number of eggs.
But if the eggs get fertilised and there is an embryo for transfer then the success is same as women of same age and with normal ovarian reserve. This is because the quality of the eggs are maintained, though the egg reserve is low in younger women and hence the embryo quality is good.
"IVF success is good once there is an embryo for transfer. However, the chance of getting an embryo for transfer is low due to less number of eggs."
Should I take DHEA/co enzyme Q10?
DHEA is a testosterone-related hormone that is a precursor to the production of both testosterone and oestrogen and has been suggested to improve follicular response to drugs during IVF and also improve embryo quality. However, the evidence in support of this is conflicting and not robust and hence it is not licensed in the Europe. Both NICE guideline and British Fertility Society does not recommend its use.
Coenzyme Q10 is a naturally occurring micronutrient that is produced by the energy-producing component (mitochondria) of our cells. It is safe to use and available over the counter. Again, the evidence in its support to improve egg quality is very limited.
"Various drugs like DHEAS/coenzyme Q10 have been suggested to reduce the rate of egg loss, but the evidence remains inconclusive"
Should I freeze my eggs?
Freezing eggs could be considered if pregnancy is not an option due to various reasons. However, to get a fair chance of live birth from frozen eggs, at least 15-20 eggs needs to be frozen. So woman with low ovarian reserve might need multiple cycles of ovarian stimulation and operation for egg retrieval if they wish to freeze their eggs. This will have financial, physical and emotional consequences. Hence it would be advisable not to delay pregnancy if possible.
"Freezing eggs might need multiple cycles of IVF to get optimum number of eggs and does not guarantee pregnancy in future.
Avoid delaying pregnancy if possible."
Written by: Dr Anupa Nandi