Egg Quality and Age — What You Can Change, and What You Cannot (2026)

In practice, egg quality means the chance that an egg produces a chromosomally normal embryo. It is not measured directly. It is inferred, mostly from the proportion of embryos found to be aneuploid when they are tested.

That inference is the reason so much writing on the subject is vague. There is no test that scores an egg. What exists is a population-level relationship between age and the proportion of embryos with the wrong number of chromosomes.

It is also why egg quality and egg quantity are different questions. Ovarian reserve markers estimate how many eggs remain. They do not describe the chromosomal competence of the eggs that are there.

Conflating the two is the single most common error in this area, and it runs in both directions. A woman of 42 with a reassuring reserve result is told her eggs are fine; a woman of 31 with a low result is told she has poor quality eggs. Neither conclusion follows — as our explanation of what diminished ovarian reserve actually means sets out, quantity and competence are separate properties, and only one of them is routinely measured before treatment.

What determines chromosomal normality is whether the egg divides its chromosomes correctly as it matures. That process becomes less reliable with age, and it is not something a blood test taken beforehand can inspect. Which is why the honest answer to “what is my egg quality?” is usually a statement about a population, not about you.

Substantially, and the relationship is steep. In one PGT-A cohort the aneuploidy rate was 26.9% in patients under 30, rising progressively to 62% in women over 40, with the probability of aneuploidy increasing roughly 10% for each additional year of age.

Two things follow. The first is that a woman over 40 often needs more eggs to reach one chromosomally normal embryo, which is why cycle planning changes with age rather than simply becoming less hopeful.

The second is that age is doing most of the work in these numbers. Any intervention claiming to improve egg quality is competing against a variable that moves ten percent a year on its own.

Read the other way round, the same figures are less bleak than they sound. An aneuploidy rate of 62% at over 40 means that just under four in ten embryos in that cohort were chromosomally normal. The problem at older ages is usually not that no normal embryo exists — it is that more eggs are needed to find one, which is a question about how a cycle is planned rather than whether it is worth attempting.

It also explains why two women of the same age can have very different outcomes without either result being surprising. These are population proportions, not individual predictions, and no test performed before retrieval tells you where in that distribution you sit. We cover the broader picture in how age impacts female fertility.

The honest answer is that no supplement has been shown convincingly to improve human egg quality. CoQ10 is the most studied, and the results are suggestive rather than conclusive.

In a randomised trial of women aged 35 to 43, aneuploidy was 46.5% in the CoQ10 group against 62.8% on placebo — a difference that looks meaningful but did not reach statistical significance. A subsequent review concluded that the available data do not clearly prove CoQ10 improves human oocyte quality, while noting improvements in laboratory and animal work.

That is a genuinely uncertain evidence base rather than a negative one. It is not the same as “CoQ10 does not work”, and it is not the same as “CoQ10 works”. Anyone presenting it as either has gone beyond the data.

The gap between the laboratory findings and the human ones is the part worth understanding. Work in animal and in-vitro models has shown improvements in oocyte maturation and reductions in chromosomal abnormality. Those results are real, and they are why the question is being asked at all. They are also routinely quoted as though they were human clinical results, which they are not.

A trial that shows a sizeable difference without reaching statistical significance is the most commonly misreported result in this field. It means the study could not rule out chance as the explanation — not that a benefit was demonstrated and not that one was excluded. Usually it means the trial was too small to settle the question. The same caution applies across the category, which we survey in natural supplements for egg health.

DHEA has better trial support than CoQ10, but in a narrower group. A Cochrane review of eight randomised trials in poor ovarian responders found DHEA pre-treatment associated with higher rates of live birth or ongoing pregnancy, with an odds ratio of 1.81.

Two caveats sit alongside that. The evidence concerns poor ovarian responders specifically, not women with normal reserve. And most poor responders do not respond to DHEA clinically, so the average effect across a trial population is not what any individual should expect.

DHEA is a hormone, not a vitamin. It is a prescribing decision, and self-medicating on the strength of an odds ratio from a trial in a different population is not what that evidence supports.

An odds ratio of 1.81 is also easier to misread than it looks. It describes how the odds shifted across a trial population, not the chance that it will work for one person. When most participants do not respond, an average benefit of that size is being produced by a minority who do — and nothing in the trial identifies in advance who those women are.

It is available over the counter in several countries, which is precisely the problem. Easy availability is not evidence of safety in a given individual, and the group in whom it has been studied is narrow. If DHEA is worth trying in your case, that is a conversation with the clinician managing your cycle, who can weigh it against your own reserve, your age and everything else on the plan.

There is no good evidence that any supplement reverses the age-related rise in aneuploidy, and no test that grades an individual egg before retrieval. Claims to either effect should be treated as marketing until a source is produced.

A useful test when you encounter a claim about egg quality is to ask what it was measured against. Improvements in laboratory or animal models are not the same as a change in live birth. A rise in the number of eggs collected is not a change in their chromosomal competence. A better-looking embryo on day five is not the same as a chromosomally normal one. Each of these substitutions appears routinely in marketing material, and each replaces the thing you care about with something easier to move.

• Ovarian reserve tests estimate quantity, not chromosomal competence.
• The CoQ10 trial data did not reach statistical significance.
• DHEA evidence is confined to poor ovarian responders, and most do not respond.
• No supplement has been shown to reverse age-related aneuploidy.

Where evidence is uncertain, the useful response is to say so. A supplement with weak but non-zero evidence and a low risk profile is a reasonable thing to discuss with a clinician. It is not a reason to delay treatment, and it is not a substitute for the conversation about age that the numbers above make necessary.

The one variable with an unambiguous effect is time, and it moves in a single direction. A woman deciding between starting treatment now and spending six months on a supplement protocol first is not choosing between two neutral options — the six months is itself part of the decision, and on the figures above it is the larger part. That is an uncomfortable thing to read and it is the most useful sentence on this page.

This is not an argument that supplements are pointless or that anyone taking them is being foolish. Wanting to contribute something to an outcome that otherwise feels entirely out of your hands is an ordinary human response, and a low-risk supplement is a harmless way to do it. The distinction worth holding onto is between something that might help a little and something that changes the picture. Nothing in the current evidence does the second.