A low egg count, formally known as diminished ovarian reserve (DOR), indicates a woman has a lower number of eggs in her ovaries than typically expected for her age. It also often implies a reduced quality of these remaining eggs. This condition reflects a woman’s reproductive potential and poses a significant challenge for fertility, making conception more difficult. Understanding the various factors that contribute to diminished ovarian reserve is important for individuals concerned about their reproductive health.
Age-Related Decline
The most significant factor contributing to diminished ovarian reserve is a woman’s age. Women are born with a finite number of eggs, which steadily declines over time. This initial supply significantly reduces by puberty.
The natural process of egg loss, called atresia, continues throughout a woman’s reproductive years; the vast majority of her egg supply degenerates. Both the quantity and quality of eggs decrease with advancing age, with a more pronounced decline occurring after the mid-30s. Older eggs are more prone to accumulating errors in their DNA during cell division, leading to a higher percentage of genetically abnormal eggs. This decline in egg quality can result in lower pregnancy rates and an increased risk of miscarriage or genetic disorders.
Medical Conditions and Genetic Factors
Beyond natural aging, several medical conditions can significantly impact a woman’s ovarian reserve. Autoimmune diseases, where the immune system mistakenly attacks healthy tissues, can target ovarian tissue. Conditions such as autoimmune thyroid disease, type 1 diabetes, lupus, and rheumatoid arthritis have been linked to lower anti-Müllerian hormone (AMH) levels, an indicator of ovarian reserve. This autoimmune attack can lead to decreased ovarian function or premature ovarian insufficiency.
Endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus, can also reduce egg count. Endometriomas, which are cysts formed by endometriosis on the ovaries, can damage surrounding ovarian tissue and decrease the number of eggs. The inflammatory environment created by endometriosis can also negatively affect egg quality and development.
Genetic factors also play a role in some cases of diminished ovarian reserve. Chromosomal abnormalities, like Turner Syndrome, where one of the two X chromosomes is partially or completely missing, commonly lead to reduced ovarian function. In individuals with Turner Syndrome, egg cells often die prematurely, leading to a significant reduction in ovarian tissue before birth or early in life. Fragile X premutation carrier status is another genetic factor that can predispose individuals to earlier or more severe decline in egg count.
Impact of Medical Treatments
Certain medical interventions can damage a woman’s ovarian reserve. Chemotherapy drugs, particularly alkylating agents, are known to be toxic to the ovaries and can lead to a rapid depletion of the primordial follicle reserve. This damage can result in premature ovarian failure and early menopause.
Radiation therapy, especially when directed at the pelvic area, can also harm the ovaries. The radiation can stop the ovaries from functioning, leading to an early menopause and infertility.
Ovarian surgery, performed for conditions like cysts or endometriosis, can also reduce ovarian reserve. During these procedures, healthy ovarian tissue containing eggs may be inadvertently removed or damaged. This can lead to a lower egg count post-surgery.
Lifestyle and Environmental Influences
Lifestyle choices and environmental exposures can negatively affect ovarian reserve. Chronic smoking is known to accelerate egg loss and ovarian aging. Studies indicate that women who smoke may have a significantly reduced ovarian reserve and a poorer response to ovarian stimulation.
Beyond smoking, certain environmental toxins might also play a role in diminishing ovarian reserve. Some industrial chemicals and pesticides are suspected of disrupting ovarian function. Additionally, severe and prolonged stress has been linked to negative impacts on ovarian function, potentially leading to ovulatory dysfunction and a decline in AMH levels.