CoQ10 and Egg Quality: What the Evidence Shows, and What It Does Not
Egg quality weighs heavily on the minds of people trying to conceive, and CoQ10 (coenzyme Q10) is one of the supplements most often recommended for it. What tends to get lost is the line between what has actually been tested in humans and what has not.
This article lays out the clinical data on CoQ10 with the number of participants and the type of study attached to each finding. The short version: a meta-analysis reports higher clinical pregnancy rates in women with diminished ovarian reserve, but no improvement in live birth rate has been demonstrated.
What CoQ10 is
CoQ10 is a coenzyme produced in the body and present in nearly every cell. It plays a part in how mitochondria generate energy, and it also has antioxidant activity. The amount the body produces tends to decline with age, and diet alone is generally not enough to make up a shortfall.
How far the "activates mitochondria" explanation goes
Eggs contain more mitochondria than almost any other cell in the body, and fertilization and early embryo development require a great deal of energy. That is where the reasoning starts: if mitochondrial function declines, egg quality declines with it.
However, no data directly show that CoQ10 improves mitochondrial function in human eggs. That mechanism was demonstrated in an animal model. In aged mice, administering CoQ10 restored the decline in egg quality and quantity, and the same study observed reduced expression of the enzymes that produce CoQ in eggs from older females in both mice and humans (PMID: 26111777). That was an intervention study in mice. What has been measured in humans is outcomes such as pregnancy rates; the mechanism remains a hypothesis.
The distinction matters. "It works because it activates mitochondria" is not yet a chain of reasoning that has been verified in people.
What has been reported in humans
Women with diminished ovarian reserve (DOR)
A 2024 meta-analysis pooled six randomized controlled trials totaling 1,529 women with diminished ovarian reserve who received CoQ10 before IVF/ICSI (PMID: 39129455). It reported:
- Higher clinical pregnancy rate (OR 1.84, 95% CI 1.33-2.53)
- More oocytes retrieved (mean difference 1.30, 95% CI 1.21-1.40)
- Lower cycle cancellation rate (OR 0.60, 95% CI 0.44-0.83)
- Lower miscarriage rate (OR 0.38, 95% CI 0.15-0.98)
The authors themselves list as limitations that the included trials were small and poorly described methodologically, and they call for rigorously conducted trials. Live birth was not among the outcomes of this meta-analysis.
Women undergoing IVF more generally
A 2020 meta-analysis pooled five randomized controlled trials totaling 449 women undergoing ART (215 in the CoQ10 group, 234 receiving placebo or no treatment). Clinical pregnancy occurred in 28.8% of the CoQ10 group versus 14.1% of controls (OR 2.44, 95% CI 1.30-4.59, p=0.006). The difference persisted when women with poor ovarian response and women with PCOS were analyzed separately (PMID: 32767206).
In the same analysis, however, there was no difference in live birth rate (OR 1.67, 95% CI 0.66-4.25, p=0.28), and none in miscarriage rate (OR 0.61, 95% CI 0.13-2.81).
A trial in women aged 35 and over
A double-blind randomized trial compared CoQ10 600 mg with placebo in women aged 35 to 43 undergoing IVF-ICSI. It was stopped before reaching its target enrollment because of safety concerns about the effect of polar body biopsy on embryo quality and implantation. Thirty-nine women were randomized, 27 received study medication, and 24 completed a cycle. The aneuploidy rate was 46.5% versus 62.8% and the clinical pregnancy rate 33% versus 26.7%, but neither difference was statistically significant, and the paper states plainly that the study was underpowered to detect a difference (PMID: 24987272).
This trial is sometimes cited as the origin of the claim that CoQ10 works in older women. The result was "no difference was found (and the study was too small to find one)" — not a demonstration of benefit.
What is not known
- Whether live birth rates improve. As above, pooled analyses show no significant difference. This is the outcome that matters most, and it is the one that remains open
- Who benefits. Higher clinical pregnancy rates have been reported in women with diminished ovarian reserve and in ART populations. No benefit has been established for women with normal ovarian function or those trying to conceive without treatment
- Optimal dose and duration. These varied across trials; no established regimen exists
At present there is not enough evidence to recommend CoQ10 to everyone trying to conceive.
Ubiquinol and ubiquinone
CoQ10 comes in a reduced form (ubiquinol) and an oxidized form (ubiquinone). The reduced form is the active one in the body; the oxidized form is converted to it. Ubiquinol is generally considered better absorbed, though it tends to cost more.
The trials cited above used different formulations. No trial has compared the two forms against each other for pregnancy outcomes.
When to start
Trials included in the meta-analyses generally administered CoQ10 for roughly one to three months before egg retrieval. Because follicles take months to develop, the reasoning is that if you are going to start, you start months ahead rather than immediately before a retrieval cycle.
The widely repeated line that "eggs take 90 days to mature, so start three months ahead" is a rounded figure aimed at a general audience; development from primordial follicle to ovulation actually takes considerably longer. The dosing periods used in trials are a firmer guide than that number.
Things worth considering
- Talk to your doctor. Even for a supplement, there are interactions and individual circumstances to weigh. If you are in treatment, discuss where it fits in your plan
- Side effects. CoQ10 is generally considered safe, though stomach discomfort has been reported. Raise anything that concerns you with your doctor or pharmacist
- Keep it in proportion. CoQ10 is one element among many. A balanced diet, regular activity, adequate sleep, not smoking and limiting alcohol rest on broader evidence
For preconception care generally, see the basics of preconception care.
Frequently Asked Questions
Q1: Will taking CoQ10 improve my egg quality?
A1: No trial has measured "egg quality" directly. What is measured in people is outcomes such as clinical pregnancy rate and number of oocytes retrieved. Higher clinical pregnancy rates have been reported in women with diminished ovarian reserve, but improved live birth has not been shown.
Q2: Who might it be worth taking for?
A2: The data come from women undergoing IVF, particularly those with diminished ovarian reserve. No benefit has been established for women with normal ovarian function or those trying without treatment. Your test results will tell you which group you fall into; discuss this with the doctor who has them.
Q3: When should I start?
A3: Trials used roughly one to three months before egg retrieval. If you start, start months ahead rather than right before the cycle.
Q4: Ubiquinol or ubiquinone?
A4: The reduced form (ubiquinol) is the active one and is thought to be better absorbed. Since no trial has compared them for pregnancy outcomes, cost and how easily you can keep taking it are reasonable things to weigh with your doctor.
Q5: What else supports egg quality?
A5: There is no drug that directly improves egg quality. A balanced diet, regular activity, adequate sleep, not smoking, limiting alcohol and managing stress are the foundation. Folic acid is recommended from before pregnancy for a separate reason.
Summary
What has been reported in humans is a higher clinical pregnancy rate in women with diminished ovarian reserve and in women undergoing IVF. What has not been shown is any improvement in live birth rate, and the mitochondrial explanation remains at the animal-model stage.
Not "it doesn't work," not "it works" — rather, this is how far the evidence currently reaches. If you are considering it, work out with your doctor whether you resemble the populations these trials studied.
References
- Clinical evidence of coenzyme Q10 pretreatment for women with diminished ovarian reserve undergoing IVF/ICSI: a systematic review and meta-analysis. Ann Med. 2024. PMID: 39129455
- Does coenzyme Q10 supplementation improve fertility outcomes in women undergoing assisted reproductive technology procedures? A systematic review and meta-analysis of randomized-controlled trials. J Assist Reprod Genet. 2020. PMID: 32767206
- Coenzyme Q10 Supplementation and Oocyte Aneuploidy in Women Undergoing IVF-ICSI Treatment. Clin Med Insights Reprod Health. 2014. PMID: 24987272
- Coenzyme Q10 restores oocyte mitochondrial function and fertility during reproductive aging. Aging Cell. 2015. PMID: 26111777 (a study in mice)