The term “egg health” encompasses two distinct concepts: quantity and quality. Egg quantity, or ovarian reserve, refers to the total number of remaining eggs in the ovaries. Egg quality refers to the egg’s genetic viability and its potential to develop into a healthy embryo and result in a live birth. Egg quality is the single most significant factor for successful conception and pregnancy outcomes. Unfortunately, direct assessment of an egg’s genetic quality is generally not possible outside of advanced fertility procedures like in vitro fertilization (IVF).
Understanding Ovarian Reserve Testing
Because direct quality assessment is unavailable, medical professionals use ovarian reserve tests (quantity and function) as a general proxy for reproductive health. These tests offer insight into how many eggs remain and how the ovaries are functioning, guiding reproductive planning. The most common markers used to gauge ovarian reserve are a combination of blood tests and ultrasound imaging.
The Anti-Müllerian Hormone (AMH) blood test measures a hormone produced by the granulosa cells of small, actively growing follicles. Since AMH levels remain stable throughout the menstrual cycle, they provide a consistent estimate of the remaining pool of follicles. A lower AMH level suggests a smaller ovarian reserve, but it does not predict the genetic health of the eggs.
The Follicle-Stimulating Hormone (FSH) test is another blood marker, typically drawn early in the menstrual cycle. FSH is the hormone the brain uses to signal the ovaries to stimulate a follicle to grow. If the ovarian reserve is diminishing, the body produces increasingly higher amounts of FSH to achieve the same result. Therefore, an elevated FSH level may indicate a lower reserve.
The Antral Follicle Count (AFC) is obtained via a transvaginal ultrasound. This technique allows a clinician to count the small, resting follicles (antral follicles) in both ovaries. The AFC provides a visual measure of the follicular pool available for recruitment in that cycle. While these three tests predict the number of eggs that might be retrieved in a fertility treatment cycle, they do not reliably predict genetic quality or the ability to conceive naturally.
The Primary Factor: Age and Chromosomal Health
The most influential determinant of egg quality is a person’s age. Unlike egg quantity, which is highly variable, the genetic integrity of the eggs declines predictably over time. Eggs are present from birth and age alongside the individual, making them some of the oldest cells in the body at the time of ovulation.
This long lifespan means the internal cellular machinery responsible for proper cell division can become impaired. The main issue impacting egg quality is the increasing likelihood of errors during meiosis, the specialized cell division process that prepares the egg for fertilization. This results in an incorrect number of chromosomes, a condition known as aneuploidy.
Aneuploidy is a major cause of implantation failure and miscarriage, as most embryos with an incorrect chromosome count are not viable. The incidence of aneuploidy in oocytes rises significantly in women over 35. This explains the decline in fertility and the increased risk of adverse pregnancy outcomes in this age group. For instance, the rate of chromosomally normal (euploid) embryos can drop from around 70% in women under 35 to 30-35% in women over 35.
Actionable Lifestyle Strategies for Egg Support
While age is the dominant factor, the three-month period before an egg is released is a window where lifestyle changes can influence its maturation environment. This 90-day phase is when the egg rapidly grows and prepares its internal structures, including the energy-producing mitochondria, making it susceptible to external influences.
Reducing exposure to environmental toxins protects developing eggs. Smoking introduces chemicals that can damage egg cell DNA and accelerate ovarian aging. Limiting exposure to endocrine-disrupting chemicals, such as Bisphenol A (BPA) found in some plastics, also helps maintain a healthy hormonal environment.
Dietary choices support the egg’s cellular processes by influencing inflammation and providing necessary nutrients. Adopting an anti-inflammatory eating pattern, like a Mediterranean-style diet, supplies antioxidants that mitigate oxidative stress. Prioritizing whole foods, lean proteins, and healthy fats ensures the egg has the energy and building blocks needed for chromosomal processing.
Managing chronic stress is important, as the sustained presence of the stress hormone cortisol can interfere with the balance of reproductive hormones required for healthy egg maturation. Prioritizing adequate sleep and stress-reduction practices helps regulate this hormonal environment. Maintaining a healthy Body Mass Index (BMI) through moderate exercise and diet supports reproductive health, as weight extremes can negatively affect egg quality.