Women are told from a young age that they are born with all the eggs they will ever have. That is true. What is less often explained is that egg quality, not just egg quantity, is one of the most significant determinants of whether conception occurs, whether an embryo develops normally, and whether a pregnancy continues.
And egg quality is not fixed.
Women are born with all the eggs they will ever have, but the body does not simply line them up in order from "best" to "worst" and use them sequentially over time.
For each cycle, a group of follicles spends roughly three months developing. Only one of those follicles will eventually release its egg during ovulation, and the body typically does not select which follicle will become dominant until around cycle days 7 to 10, only several days before ovulation itself. That egg has spent months maturing within the hormonal, metabolic, mitochondrial, and inflammatory environment surrounding it.
That distinction matters because egg quality is not determined solely by age or by some fixed ranking established at birth. The cellular environment in which an egg matures plays a major role in mitochondrial function, chromosome division, oxidative stress, and embryo development.
Age still matters enormously. But the biology is far more dynamic than the simplistic idea that the body just "uses up the good eggs first."
That three month window is one of the most important and most underutilized opportunities in reproductive medicine.
Why mitochondria are at the center of this conversation
Eggs are the most mitochondria-dense cells in the human body. A mature egg contains approximately 100,000 mitochondria, far more than any other cell type. This is not coincidental. The energy demands of egg maturation, fertilization, and early embryo development are extraordinary, and mitochondria are responsible for generating the ATP that powers all of it.
When mitochondrial function is compromised, the consequences are downstream and significant: impaired chromosome segregation during meiosis, higher rates of aneuploidy, reduced fertilization capacity, and poor embryo development.
Much of the preconception supplement conversation ultimately converges on mitochondrial support because mitochondrial function sits so centrally within egg maturation itself. Not because supplements are a substitute for broader health, but because the cellular energy environment in which an egg matures is genuinely modifiable.
What the evidence actually supports
CoQ10 as ubiquinol
CoQ10 is the most extensively studied supplement for egg quality and the one with the strongest clinical rationale. It is essential for mitochondrial ATP production and functions as a powerful antioxidant that protects eggs from oxidative stress during the maturation process.
A 2024 systematic review and meta-analysis of over 1,500 women across six randomized controlled trials found that CoQ10 supplementation significantly improves pregnancy rates, egg quality, embryo quality, and reduces the amount of hormone stimulation required during IVF cycles, with the most pronounced benefit in women with diminished ovarian reserve.
The honest caveat is that evidence for live birth rates remains limited and further large trials are still needed. But the mechanistic rationale is strong, the safety profile is excellent, and the signal in the existing data is remarkably consistent.
The form matters. CoQ10 exists as ubiquinone and ubiquinol. Ubiquinol is the active, reduced form that does not require conversion in the body to be biologically useful. After approximately age 35, the body's ability to convert ubiquinone to ubiquinol declines, making ubiquinol the clinically preferable form for most women in this context.
Dosing in most fertility studies ranges from 400 to 600mg daily, taken with a fat-containing meal for optimal absorption. The 90-day follicle maturation window means supplementation should ideally begin at least three months before attempting conception.
NMN
NMN, or nicotinamide mononucleotide, is a precursor to NAD+, a coenzyme central to mitochondrial energy metabolism and DNA repair. NAD+ levels decline significantly with age, and this decline has been implicated in the deterioration of egg quality that accelerates in the mid to late 30s.
A 2025 systematic review published in the Journal of Assisted Reproduction and Genetics by researchers at University College London found that NMN supplementation improves mitochondrial regulation, reduces oxidative stress, and modulates inflammatory and apoptotic pathways in oocytes across animal models. Single-oocyte RNA sequencing of 46 human oocytes confirmed that NAD+ related genes are actively expressed at all stages of egg maturation, suggesting direct biological relevance.
The honest caveat is that the majority of current evidence remains preclinical, and human fertility data is still limited. But the mechanism is compelling and the safety profile reasonable. For women over 35 with diminished ovarian reserve or prior IVF poor response, NMN is among the more evidence-informed options in the current preconception supplement landscape.
Myo-inositol
Myo-inositol is a naturally occurring compound that plays a role in insulin signaling and FSH receptor function in the ovary. It is the most studied supplement for egg quality in women with PCOS, where insulin resistance directly impairs follicular development and egg maturation.
Research suggests that myo-inositol in a 40:1 ratio with d-chiro-inositol improves ovulation, egg quality, and embryo quality. A review published in Reproductive Biology and Endocrinology found that combined myo-inositol and melatonin supplementation improves both fertilization rates and pregnancy rates, with co-treatment outperforming either supplement alone.
For women without PCOS, the evidence is less robust but the mechanism still applies. Insulin sensitivity influences ovarian function broadly, and myo-inositol is generally considered low risk.
Melatonin
Melatonin is known primarily as a sleep hormone but functions equally as a potent antioxidant within follicular fluid, where it helps protect maturing eggs from oxidative damage. Follicular fluid melatonin concentrations are significantly higher than circulating blood levels, suggesting an active local role in ovarian physiology.
Multiple studies have shown associations between melatonin supplementation and increased numbers of eggs retrieved, higher rates of mature eggs, and improved embryo quality during ART cycles. Clinical pregnancy rates appear to improve in some studies, though live birth rate data remains limited.
Timing matters. Melatonin is typically taken at night, and lower doses in the range of 1 to 3mg are generally preferred over higher doses in this context.
DHEA
DHEA is an adrenal androgen precursor that supports ovarian follicle development and estrogen production. Levels decline with age and are often lower in women with diminished ovarian reserve.
Research published in Reproductive Biology and Endocrinology found that DHEA supplementation improves ovarian response, increases eggs retrieved during IVF, and enhances embryo quality, with the most consistent benefit observed in women with diminished ovarian reserve. Typical protocols use micronized DHEA at 25mg three times daily for a minimum of 6 to 12 weeks before an IVF cycle.
DHEA is not appropriate for everyone. Women with PCOS, androgen excess, or certain hormone-sensitive conditions should avoid it. Baseline hormone assessment is important before starting.
Methylated prenatal vitamins
Folate as methylfolate rather than folic acid may be particularly important for women who carry MTHFR variants affecting folate metabolism, a common polymorphism that can impair conversion of folic acid into its active form. Methylated B12 and other activated B vitamins help support methylation, DNA synthesis, and early fetal development.
For preconception, a high-quality prenatal started at least three months before attempting conception establishes the nutritional foundation everything else builds on.
What preconception care often misses
Supplements are one part of a much larger picture. Several commonly overlooked physiologic factors have direct effects on egg quality and reproductive outcomes.
Thyroid function
Thyroid optimization matters significantly in preconception care. Both overt and subclinical hypothyroidism are associated with impaired implantation, increased miscarriage risk, and poorer reproductive outcomes. Because of this, reproductive endocrinology and obstetric guidelines generally target a preconception and first trimester TSH below 2.5.
But thyroid evaluation in fertility care should not stop at TSH alone. Free T4, thyroid antibodies, symptoms, and overall clinical context matter as well, particularly given the complex relationship between thyroid function, ovulation, implantation, and early pregnancy maintenance.
Iron status
Iron repletion is frequently overlooked. Iron deficiency without anemia, particularly ferritin levels below 50 ng/mL, may impair mitochondrial function, reduce exercise tolerance, and compromise cellular energy availability.
Given the extraordinary energy demands of egg maturation, iron status deserves attention before conception attempts begin.
Blood sugar and insulin signaling
Blood sugar stability directly influences ovarian function through insulin and IGF-1 signaling pathways. Insulin resistance, even before it becomes obvious on standard labs, may suppress ovulation, shorten the luteal phase, and contribute to elevated androgen levels that impair follicular development.
A fasting insulin alongside fasting glucose often provides a much more complete picture than glucose alone.
Chronic inflammation
Chronic inflammation appears repeatedly throughout the fertility literature as a common denominator in poorer reproductive outcomes. Elevated hsCRP, gut dysbiosis, autoimmune activity, chronic sleep deprivation, and metabolic dysfunction all influence the inflammatory environment in which eggs mature.
This is why preconception care that focuses exclusively on supplements while ignoring sleep, metabolic health, nutrition, gut health, and inflammatory physiology is incomplete.
The three month window
Follicles take approximately 90 days to mature from their early developmental stage to ovulation. The cellular environment during that entire period influences the quality of the egg that ultimately emerges.
This means the work of preconception support does not begin the month someone starts trying to conceive. It begins several months earlier.
The supplement protocols, nutritional optimization, thyroid evaluation, iron repletion, sleep regulation, and metabolic support are all most effective when established well before the follicle destined for ovulation begins its maturation journey.
This is not widely communicated. Many women begin preconception supplements the month they decide to try.
The bigger picture
Preconception care is not about manufacturing a perfect outcome. Fertility is complex and deeply human, and egg quality is only one piece of a much larger story.
But the biology is clear: eggs mature within an environment shaped by mitochondrial function, oxidative stress, nutritional status, hormonal balance, inflammation, and metabolic health.
These variables meaningfully influence the physiologic environment in which conception becomes possible, embryos develop, and pregnancies continue.
That matters.
And it deserves far more attention in modern preconception care than it currently receives.
← Back to Journal