Assisted fertilization

How is a woman’s ovarian reserve determined?

Understanding the woman’s ovarian reserve is useful for understanding her chances of conceiving by natural means and the response to stimulation protocols in assisted reproduction treatments. 

The ovarian reserve generally indicates the capacity of the ovary to produce oocytes capable of being fertilized and giving rise to a successful pregnancy (baby in arms). As maternal age increases, the number of oocytes that can be successfully recruited for possible pregnancy decreases.

The ovarian reserve of a woman, in a given period of her life, is therefore represented by the count of follicles left and available to be recruited during menstrual cycles. We know that women are born with a predefined baggage of pro- mercial follicles (about 1-2 million) while at the first menarche they do not exceed 300-400 thousand.

The number of follicles decreases progressively (even if the woman takes hormonal contraception) and increasingly faster with age.

How can this number of remaining follicles be determined as accurately as possible?

Tests to determine the woman’s ovarian reserve

Tests for determining ovarian reserve should never be read individually. These are tests that must always be carried out before starting assisted reproduction treatment . They are recommended when pregnancy does not occur after a year of targeted attempts, or after 6 months if the woman is over 36 years of age.

The main tests for determining a woman’s ovarian reserve include the dosage of FSH (follicle stimulating hormone), AMH  ( anti-Müllerian hormone) and antral follicle count. 

While the dosage of the anti-Müllerian hormone can be performed at any time of the menstrual cycle, that of the FSH and the antral follicle count (AFC) must be done between the 2nd and 5th day of the menstrual cycle (i.e. in conditions defined as basal ).

FSH values ​​are defined as good if below 9, optimal if below 6 mIU / ml.

When the value repeatedly exceeds 10-15 mIU/ml it is an indication of a reduction in the ovarian reserve.

AMH values ​​decrease in parallel with the reduction of ovarian follicles as a woman ages. They are usually low below 0.4-1.2 ng/ml.

The value of AMH is important in assisted fertilization treatments because it is able to predict the woman’s ovarian response to ovarian stimulation protocols better than FSH and other markers .

Its predictive ability is similar to that of the antral follicle count but has the advantage of being able to predict the risk of hyperstimulus . For this reason, the AMH values ​​are fundamental in customizing an assisted reproduction protocol.

There is a risk of hyperstimulus for example if the value is above 3.36 ng/ml and the antral follicle count above 16.

Does estradiol have any significance in the ovarian reserve?

According to some studies, the presence of high estradiol values ​​in basal conditions (in the very first days of the menstrual cycle) could indicate a reduction in ovarian reserve even before the FSH values ​​increase.

According to a study which took into consideration 231 patients undergoing assisted fertilization treatment, if estradiol values ​​are higher than 60 pg/ml there is a greater risk of cancellation of the stimulation protocol due to lack of response, and a greater risk of low oocyte retrieval, compared to women with lower baseline estradiol values.

The count of antral follicles for the determination of the ovarian reserve

The antral follicle count is performed through a transvaginal ultrasound (2D or 3D), generally in the very first days of menstruation (although a good sonographer is able to make evaluations in different periods of the menstrual cycle).

During the counting of the antral follicles, the volume of the ovaries and the number of antral follicles of size 2-10 mm (or better yet 2-6 mm) are evaluated.

The number of antral follicles detected by ultrasound represents the pool of follicles that will be recruited in that particular menstrual cycle and on which the gonadotropins will act to bring them to maturation.

A good ovarian reserve is usually present if the sum of the volume of the two ovaries is greater than 6cm³, and if the sum of the number of antral follicles is equal to or greater than 7.

The count of the antral follicles and the evaluation of the hormonal values ​​of FSH and AMH allow us to hypothesize what the woman’s response will be to the stimulations in an assisted fertilization process. In fact, the stimulation protocol is decided on the basis of these parameters .

In addition to all these parameters, the age of the woman also affects the quality of the oocyte.

Indeed, a series of data indicate that after the age of 38-40 in women there is an evident reduction in the quality of her oocytes  which appears to be independent of the ovarian reserve and linked, for example, to oxidative damage.

Therefore, the determination of a woman’s fertility requires a very extensive and accurate evaluation by experts in reproductive medicine.

Dr Kathryn Barlow

Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.

Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.

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