Low ovarian reserve
Low ovarian reserve
The ovarian or follicular reserve is the number of oocytes that can participate in the fertilization process; a set of primordial follicles (that have not entered into growth), which contain germ cells – oocytes. The quantity and quality of all follicles are determined during the period of intrauterine development of the girl. By the time of birth, the girl has 5-7 million eggs in her ovaries. Before the first menstruation, there are already 300-500 thousand eggs left.
Reduced ovarian reserve
A reduced ovarian reserve indicates that a woman has a noticeably reduced supply of eggs in the ovary and the likelihood of becoming pregnant is reduced. Also, it is worth considering that each biological age has its own ovarian reserve.
To assess the ovarian reserve, the following examinations are carried out:
pelvic ultrasound scan to count the number of antral follicles in each ovary;
AMH (Anti-Müllerian hormone) level test.
A depleted reserve is when AMH is below 0.1 before 40 and when AMH is below 0.4 at the age of 40 and older. Or when AFC (i.e., the number of antral follicles in two ovaries) is below 3.
Usually women of late reproductive age – after 35 years, are diagnosed with low ovarian reserve.
Causes of low ovarian reserve
Age of the woman (over 37 years old).
Surgeries on the ovaries (ovarian resection, ovarian cauterization at PCOS, removal of ovarian cysts), chemotherapy or radiation therapy.
The initially small supply of eggs at birth as a hereditary factor (this is very likely if the mother or grandmother stopped menstruating early).
A big problem with a reduced ovarian reserve of the ovaries is that when receiving a small number of oocytes, it is not possible to produce a sufficient selection of embryos due to their low quantity, or it is not possible at all to obtain a blastocyst for transfer into the uterine cavity.
The more oocytes obtained in the ART program after stimulation and puncture, the higher the chances of getting a euploid embryo (high-quality, with a normal chromosome set). However, it is known that in order to obtain 1 euploid blastocyst (that is, a good quality embryo) from a woman under the age of 35, it is necessary to get 6 eggs, at the age of 38-40 years – 11 oocytes, and after 42 years – on average, more than 17-18 oocytes.
That is, a key success factor in IVF programs is the woman's age. Getting 2-3 oocytes from a 30-year-old woman gives a much higher chance of a successful outcome than getting the same 2-3 oocytes from a 40-year-old woman.
An effective way to increase ovarian reserve has not yet been found.
Often, with a low ovarian reserve, it is not possible to conceive a child naturally. In such cases, it is necessary to switch to ART programs as soon as possible.
In ART programs, in order to obtain a sufficient number of eggs and subsequently embryos suitable for transfer, more stimulations may be required – 3-5 attempts in embryo accumulation programs. If it is impossible to stimulate superovulation (the number of woman’s antral follicles on both ovaries is less than 3), it is possible to try in natural cycles, while maintaining own ovulatory function in a woman.
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