A woman's egg reserve or ovarian reserve is an indicator of her egg count at a particular stage of her life. In other words, it is an indicator of female fertility.
The higher the egg count, the greater the chances of getting pregnant. If your egg count is poor, you may need to turn to IVF to have a baby.
Below you have an index with the 9 points we are going to deal with in this article.
What does 'egg reserve' mean?
Women are born with all the eggs that they will have during their lifetime. On average, their supply of eggs at birth is around 1 million oocytes. At puberty, this amount is reduced to 400,000-500,000. After the first ever menstrual period, women release an egg per month, and it is estimated that only 400-500 will be ovulated during their reproductive years. The rest will degenerate eventually.
A woman's ovarian reserve is defined as the supply of egg that she has depending on age. It is a determining factor when trying to conceive, either naturally or by Assisted Reproductive Technology (ART).
The most fertile period in a woman's life encompasses from ages 16 to 30. At this point, both her egg supply and quality should be excellent. Unfortunately, the egg reserve goes through a major decrease from age 35-37.
At age 40, the ovarian reserve is considerably low, and will keep on diminishing until its complete depletion approximately at ages 45-55. This period marks the beginning of a new phase in the woman's reproductive life: menopause.
Unluckily, some women experience a decrease in the quality and quantity of their eggs earlier than expected. This is known as early or premature menopause. For this reason, women who want to have children after age 35 should have their ovarian reserve tested.
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Causes of low egg count
As explained above, age plays a major role when it comes to evaluating the ovarian reserve. As a matter of fact, they are inversely proportional factors, that is, the older, the lower the supply and quality of eggs.
In addition to age, there exist other factors that can have a negative impact on the egg reserve and female fertility. These factors can lead to premature menopause or premature ovarian failure (POF), which refers to a situation in which menopause can happen earlier than usual.
The risk factors and conditions that can affect a woman's egg reserve include:
- Medical and surgical procedures
- Environmental factors
- Being exposed to pesticides or toxic agents
- Unhealthy habits
- Certain conditions (e.g. endometriosis or pelvic inflammatory disease)
How fast a woman's egg reserve diminishes varies on a case-by-case basis. This is the reason why menopause does not start at the same age in all cases.
What is a good ovarian reserve?
Your ovarian reserve can be evaluated by measuring the levels of the following key hormones:
Follicle-stimulating hormone (FSH)
FSH is one of the hormones responsible for regulating the menstrual cycle. It is released by the pituitary gland to trigger the production of eggs. When the number of eggs is low, FSH levels increase to activate the ovary. In other words, low FSH levels translate into low ovarian reserve.
Normal FSH levels should be below 6 mIU/ml. Nevertheless, if they range between 6 and 9 mIU/ml, we can consider that the woman has a good ovarian reserve as well.
It is considered moderate if the levels of FSH vary from 9 to 120 mIU/ml, and low if they range between 10-13 mIU/ml. FSH levels above 13 mIU/ml indicate low ovarian reserve, that is, the woman is near menopause.
For FSH levels to be properly measured, a blood test is donde on days 3 to 5 of the menstrual cycle, considering the first day of the last menstrual period (LMP) the first day of the cycle.
Anti-müllerian hormone (AMH)
AMH is released by the ovarian follicles, that is, the ovarian structures that are home for the developing eggs. When the levels of AMH are high, it means that there is an elevated amount of mature eggs. If they are low, it means that the egg reserve is low.
Levels of AMH that range between 0.7 and 3.5 ng/ml indicate your ovarian reserve is normal. On the other hand, levels below 0.7 are considered an indicator of low ovarian reserve.
The levels of AMH in blood can be measured any day of the cycle. Contrary to what happens with FSH, its levels don't vary throughout the cycle. It makes the results of AMH tests very accurate, given that its levels are fairly constant and independent from other factors.
The levels of estradiol increase as follicles develop. For this reason, measuring the levels of E2 can be very helpful to evaluate a woman's egg count. Simply put, the higher the levels of estradiol, the better the supply of eggs available per cycle.
Too high levels of estradiol, however, during the first days of the cycle (days 3-5) indicate low ovarian reserve. E2 levels below 40 pg/ml indicate that the woman has an optimal ovarian reserve.
Antral Follicle Count (AFC)
Since the moment a woman reaches puberty, a set of follicles develops each month, although just one reaches the ovulatory stage, that is, the phase in which just one mature egg cell is released. The remaining will degenerate eventually.
We distinguish the following phases of follicle development: primordial, primary, secondary, antral, and preovulatory (also known as Graafian follicle).
Antral follicles are marked by the formation of a fluid-filled cavity called antrum. This allow them to be seen by ultrasound scan. In short, counting the number of antral follicles can give us an approximate idea of the woman's egg supply status.
AFC results are more accurate if donde on days 3 to 5 of the menstrual cycle.
What is the best age for a woman to get pregnant?
As the ovarian reserve diminishes with age, so do her chances of getting pregnant naturally. In fact, this is the reason why nowadays there is an increasing number of women who have no alternative but to turn to fertility treatment to have children due to issues with their supply of eggs.
As explained above, advanced maternal age does not only affect the egg count, but also their quality. To put it simply, from age 35-37 onwards, getting pregnant becomes a hard task.
Low ovarian reserve is often the cause behind a woman's inability to get pregnant, either naturally or by means of IVF.
For this reason, when a woman undergoes fertility tests, evaluating her egg reserve is crucial, since it is an indicator of her response to ovarian stimulation and her prognosis.
Egg donation is the recommended fertility treatment in cases of declining ovarian reserve. It is a type of In Vitro Fertilization (IVF) that involves the use of donor eggs to increase the chances for pregnancy.
Interview of Dr Miguel Dolz about ovarian reserve
According to Dr. Miguel Dolz, it is fundamental to evaluate the ovarian reserve because the quantity of eggs that will be collected during in vitro fertilization treatment will define the reproductive prognosis of the couple.
The optimal ovarian reserve should be adjusted to the patient's age. In general, the standard value is 10 antral follicles and the FSH hormone level should be less than 10. In this case, the ovarian reserve is considered to be quite normal.
FAQs from users
Why is age such an important factor in a woman's fertility?
We women are born with all the oocytes we will have for life. A process of natural loss of the quantity and quality of oocytes occurs throughout life. This decrease in the quantity and quality of the eggs is more pronounced after 35 years old.
For this reason, after the age of 35, the chances of pregnancy decrease and the probability of miscarriage increases.
Is there a relation between ovarian reserve and egg quality?
Ovarian reserve is a measure of the quantity and quality of the eggs; it is best measured by a combination of chronological age, antral follicle count (AFR) on ultrasound, and anti-mullerian hormone (AMH).
An AFR of less than 11 reflects diminished ovarian reserve and less than 6 is severe. AMH levels below 1.6 have been shown to reduce the number of eggs retrieved with IVF and may predict pregnancy outcome. Levels below 0.4 are severe.
How does low ovarian reserve affect IVF success rates?
We know as ovarian reserve or egg count the amount of eggs a woman carries at a particular stage of her lifetime. It is an indicator of her fertility at that point.
Measuring a woman's ovarian reserve allows us to determine the ability for her ovaries to produce eggs with fertility potential, that is, able to result in viable embryos, able to attach to her endometrial lining.
Moreover, as the egg reserve diminishes, so does the quality. This translates into a higher number of complications to achieve pregnancy, as well as to an increased miscarriage rate.
For all these reasons, the supply of eggs of females is a key factor to getting pregnant naturally as well as by means of IVF. The success rates of IVF are lower in women with a decreased egg supply.
Recommended for you: What Is a Good Number of Eggs Retrieved for IVF?
Can a woman produce more eggs?
No, it is not possible. As explained above, all women are born with a limited supply of eggs, that is, with the total number of eggs that they will carry throughout their lifetime. The ovarian reserve diminishes with age until its complete depletion when the woman reaches menopause.
Can eggs come out during period?
Yes, but this is precisely how every girl's menstrual cycle works. If fertilization doesn't occur, the egg released by the ovary will be flushed out along with the uterine lining in the form of menstrual flow. Obviously, you can't see the egg come out during your period.
Do you run out of eggs at menopause?
Yes, in fact, that is the definition of menopause. When a woman hits this stage in her reproductive life, it literally means that her ovaries have run out of oocytes.
How do I know how many eggs I have left?
A woman's ovarian reserve can be predicted through a number of tests, as I have explained above. So even though it can predicted, knowing the exact amount is not possible.
The most common test used to measure it is the one that evaluates AMH (anti-Müllerian hormone). Learn more: Anti-Müllerian Hormone (AMH).
Is ovarian reserve related to blood type?
In recent years, several studies have suggested the existence of an association between blood type ABO and decreased ovarian reserve and poor response to ovarian stimulation. However, the number of studies confirming this is still insufficient. Further studies are needed to confirm this link.
How many eggs does a woman drop during ovulation?
Every menstrual cycle, it is estimated that about 15 to 20 eggs start to mature in each ovary. However, only one egg is "drop", that is, your ovary releases just one egg per cycle.
Other people also read: What Is Ovulation? – Date, Symptoms & Most Fertile Days.
How many eggs does a woman release on Clomid?
Clomid, Clomifene or Clomiphene is a medication used for IVF ovarian stimulation. The purpose is to produce more than one egg per cycle (i.e. superovulation). The particular number of eggs a woman will be able to release on Clomid depends on each IVF patient and the response of her ovaries to IVF meds.
Suggested for you
If you are trying to get pregnant through IVF, you might be interested in learning more about the response of the ovaries to IVF medications. Click here to continue reading: Poor Responders in IVF Cycles – Management & Best Protocols.
To get an overall idea of the most common tests used to determine a woman's fertility, click here: Female Fertility Tests – How Do You Know if You Can’t Get Pregnant?
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Video ReproducciónAsistida.Org - Entrevista sobre la Reserva ovárica - by Dr. Miguel Dolz, on November, 2th 2017. [See original video in Spanish here]
FAQs from users: 'Why is age such an important factor in a woman's fertility?', 'Is there a relation between ovarian reserve and egg quality?', 'How does low ovarian reserve affect IVF success rates?', 'Can a woman produce more eggs?', 'Can eggs come out during period?', 'Do you run out of eggs at menopause?', 'How do I know how many eggs I have left?', 'Is ovarian reserve related to blood type?', 'How many eggs does a woman drop during ovulation?' and 'How many eggs does a woman release on Clomid?'.