Definition and Overview
Ovarian reserve refers to a woman’s remaining supply of quality eggs that can be used to achieve pregnancy. It is one of the important factors being looked into when a woman is having a hard time conceiving and when formulating a fertility treatment for her.
Every woman is born with all the eggs that she will ever have in her lifetime (approximately two million). About eleven thousand of these eggs naturally die every month before puberty and more eggs are damaged or lost as a woman ages regardless if she is pregnant, on birth control, or has infrequent menstrual cycles. Damaged or abnormal eggs lower the chances of getting pregnant and increase the chances of miscarriage and the risk of having a baby with certain types of abnormalities.
A woman's ovarian reserve thus declines over time. Oocytes decrease both in quality and quantity and they do not regenerate. When a woman no longer has normal eggs in her ovaries, she becomes infertile (unable to get pregnant). At around 51-55 years old, when a woman is expected to enter menopause, she only has about 1,000 eggs and most, if not all, are abnormal or damaged. Younger patients can also suffer from premature ovarian ageing or when their expected ovarian reserve is significantly lower for their age.
Diminished ovarian reserve (DOR) is characterised by poor fertility outcomes and is considered a major challenge in the field of reproductive medicine. Patients with DOR find it extremely difficult to get pregnant even when assisted reproductive technology (ART), such as in vitro fertilisation and intrauterine insemination, are used.
Causes of Condition
Diminished ovarian reserve, which is one of the primary reasons for female infertility, is a normal part of the ageing process. A woman’s eggs naturally die or suffer from irreparable damage as she gets older. However, the condition becomes a problem if the number of eggs declines at a much faster rate, making it difficult for some women to achieve pregnancy during their childbearing years. This problem can be caused by the following:
Endometriosis – A condition that causes endometrial tissue to be trapped outside of the uterus. It can cause infertility, painful periods, and pain in the pelvic area.
Previous ovarian surgery
Exposure to toxic chemicals
Cancer treatments such as chemotherapy and radiotherapy – Cancer patients can preserve their fertility prior to undergoing any form of treatment that can destroy their eggs. Their options include embryo or egg freezing, ovarian tissue freezing, and ovarian suppression or transposition.
DOR has no specific signs and symptoms aside from slight changes in menstrual cycles such as spotting before the full menstrual flow and shorter or longer cycles than usual. Most women become aware of their condition when they consult their doctors because they are not getting pregnant after more than one year of unprotected vaginal sex and undergo ovarian reserve testing.
Ovarian reserve testing is an integral part of fertility treatments and is often performed in women older than 35 years and have an increased risk of diminished ovarian reserve. These include those who:
Have undergone cancer treatment
Received radiation treatment in the pelvic area
Received gonadotoxic therapies
Have undergone ovarian surgery for endometriosis
The main objective of ovarian reserve testing is to assess not just the quantity but also the quality of the remaining oocytes to predict a woman’s reproductive potential. Women with DOR are counseled that their window of opportunity to conceive could be shorter than anticipated to help them explore her options.
Who to See and Types of Treatments Available
Treatment of female infertility due to diminished ovarian reserve focuses on helping women achieve pregnancy. Timely diagnosis and prompt management are crucial as the sooner treatment is initiated, the better the pregnancy chances are.
The condition can be diagnosed with blood tests designed to measure the levels of follicle stimulating and anti-Mullerian hormones. Low AMH levels and high levels of FSH confirm diminished ovarian reserve and the need for aggressive treatment. Transvaginal ultrasonography is also often performed to gather more information and confirm the diagnosis.
Treatment options include the following:
Controlled ovarian stimulation - This is performed prior to in vitro fertilisation or intrauterine insemination. It involves stimulating the ovary using high doses of follicle-stimulating hormones to improve the quality of oocyte and embryo as well as maximise the number of mature eggs that a woman produces for a specific cycle.
Intrauterine insemination (IUI) - Involves placing sperm as close to the ovulating eggs as possible to facilitate fertilisation. For improved outcomes, lab work monitoring and pelvic ultrasound are used to achieve timely insemination.
In vitro fertilisation (IVF) - Involves the surgical retrieval of eggs through the vagina and fertilising them with sperm in a lab. The embryo is then implanted into the woman’s uterus to increase the chances of pregnancy.
IVF and IUI success rates for patients with DOR are highly dependent on the number and quality of eggs obtained during the egg retrieval process. Ideally, at least four mature follicles should form after ovarian stimulation so there will be more embryos to choose from for embryo transfer.
American Infertility of New York City https://www.centerforhumanreprod.com/infertilityedu/causes/diminished-ovarian-reserve/treatment/
Medications for inducing ovulation: A guide for patients. American Society for Reproductive Medicine. http://www.reproductivefacts.org/BOOKLETMedicationsforInducingOvulation/.
The American Congress of Obstetricians and Gynaecologists. https://www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Gynecologic-Practice/Ovarian-Reserve-Testing
Testing and interpreting measures of ovarian reserve: a committee opinion. Practice Committee of the American Society for Reproductive Medicine. Fertil Steril 2012;98:1407–15.