Nutrifact Guide · Last updated October 2026 · Educational information only, not medical advice

If you have been trying to get pregnant for a while and nothing is happening, it is very easy to end up scrolling supplement pages late at night. Everything promises something: better egg quality, balanced hormones, a “natural” boost. When you want a baby badly, a bottle with a tidy label feels like taking action.

We get that. But the honest picture is more mixed than the marketing. Some supplements have a little research behind them. Many have almost none. And a few claims are bad enough that the US Food and Drug Administration (FDA) has stepped in.

This guide pulls together what major health bodies, review studies and regulators have actually said about female infertility and the supplements people use for it. We have kept the language simple and we point to every source at the end, so you can check the details yourself. One thing to say up front: supplements are not a replacement for finding out why pregnancy is not happening. That part matters far more.

How common is female infertility?

More common than most people think. A major World Health Organization (WHO) report found that roughly 1 in 6 adults worldwide experience infertility at some point. The lifetime figure was about 17.8% in high-income countries and 16.5% in low- and middle-income countries. The report also pointed out that many countries still lack good data, so the real numbers may be different in some places.

Infertility is not only a women’s issue. The American Society for Reproductive Medicine (ASRM) notes that men are involved in about half of infertility cases. Still, in this article we focus on the female side, because that is where most of the supplement marketing is aimed.

Doctors usually define infertility as not getting pregnant after 12 months of regular, unprotected sex. That sounds long, but here is some reassurance. According to ASRM, about 80% of couples who are going to conceive do so within the first 6 months of trying. So a few months without a pregnancy test turning positive is common and does not mean something is wrong.

What causes female infertility?

There is no single cause. A medical review in StatPearls, a free resource from the US National Library of Medicine, says female factors contribute to roughly half of infertility cases. The main groups are these:

• Ovulation problems. The review estimates these account for about 25% to 40% of cases. The most common reason for not ovulating is polycystic ovary syndrome (PCOS), which explains about 70% of anovulation. Thyroid problems and high levels of the hormone prolactin can also stop ovulation.

• Blocked or damaged fallopian tubes. Past infections, scarring or surgery can make it hard for egg and sperm to meet.

• Endometriosis. Tissue similar to the womb lining grows outside the womb and can affect the ovaries and tubes.

• Problems with the womb itself, such as fibroids or structural differences.

• Early loss of ovarian function, where the ovaries slow down much earlier than expected.

• Age. More on this next.

A quick note on names. In May 2026, an international group officially renamed PCOS to polyendocrine metabolic ovarian syndrome, or PMOS, to better describe how the condition affects hormones and metabolism, not just the ovaries. The change is being phased in over several years, so you will see both names for a while. Australia’s RANZCOG says the condition affects an estimated 10% to 13% of women of reproductive age.

Age is the biggest factor

This is the part nobody enjoys, but it is the most important fact in the whole field. ASRM states that fertility falls by about half at age 40 compared with a woman’s late twenties and early thirties. The reason is that eggs are more likely to carry chromosome errors as a woman gets older, which lowers the chance of pregnancy and raises the risk of miscarriage. No supplement has been shown to reverse that. For that reason, we are cautious about any product that claims to “turn back” egg age.

When should you see a doctor?

ASRM says to seek help after 12 months of trying. If you are 35 or older, it recommends getting checked after 6 months, because time matters more. Earlier help may also make sense if your periods are very irregular or you already know about a condition such as endometriosis or PCOS.

A basic fertility workup usually looks at whether you ovulate, whether your tubes are open, and what your womb looks like. Your partner’s semen should be checked too. It is quick, it is inexpensive compared with months of guessing, and it can point you to the real fix.

Medical treatment comes first

It helps to know what the strongest treatments look like, so supplements can be put in proper context.

For women with PCOS who do not ovulate, a medicine called letrozole has become a first choice in many guidelines. In a large US trial known as PPCOS II, live birth rates were about 27.5% with letrozole compared with 19.1% for the older drug clomiphene. A more recent meta-analysis of 32 randomized trials also found higher ovulation, pregnancy and live birth rates with letrozole. In some countries, including the UK, letrozole is used off-label for this purpose, so your doctor’s local rules apply.

Other routes include treating thyroid problems, surgery for certain tube or womb issues, intrauterine insemination (IUI), and in vitro fertilization (IVF). We will not cover those in detail here. The point is simple: these options have been tested in large trials. Most supplements have not.

The European Society of Human Reproduction and Embryology (ESHRE) makes the same point about the “add-ons” that clinics sometimes offer on top of IVF. In its 2023 guidance with 42 recommendations, none could be based on high-quality evidence and only four on moderate-quality evidence. Even in specialist clinics, a lot of what people try rests on thin proof.

Who checks supplements? Almost nobody, before sale

Before going supplement by supplement, you should know how they are regulated, at least in the United States. The FDA says it does not approve dietary supplements for safety or effectiveness before they are sold. Companies are responsible for making sure their products are safe and correctly labeled. The FDA also states that supplements are not approved to treat or prevent disease.

Under the law, a supplement label may say it supports a normal body function. It may not claim to prevent, treat or cure a disease, and infertility counts as one. Companies must keep evidence for the claims they do make, and the label must carry the familiar disclaimer.

So when you see “cures infertility” or “fixes ovarian cysts” on a supplement page, that is already a red flag. We come back to this below.

What the evidence says about popular supplements

Folic acid: the one everyone agrees on

If there is only one supplement you take while trying to conceive, ASRM’s answer is folic acid: at least 400 micrograms a day. The main reason is protection against neural tube defects in the baby, such as spina bifida, not a boost to fertility. ASRM mentions that some cohort studies suggest folate might help fertility too, but it says better studies are needed. It is cheap, well studied and widely recommended, so it is the sensible starting point. Many people take it as part of a prenatal vitamin.

Coenzyme Q10 (CoQ10)

CoQ10 is an antioxidant that helps cells make energy, and egg cells need a lot of it. It is one of the most talked-about supplements for “egg quality”. So what do the studies show?

A meta-analysis of five randomized trials with 449 women having assisted reproduction found that CoQ10 was linked to more clinical pregnancies. However, it did not change live birth rates or miscarriage rates. Clinical pregnancy and live birth are not the same outcome, and live birth is the one people actually care about.

A larger network meta-analysis of 16 trials with 2,323 women ranked CoQ10 as the best option for live birth among the antioxidants it compared. But the result came with a very wide margin of uncertainty (the confidence interval ran from about 1.07 to 5.38), which means the true effect could be small or large. A review focused on women with low ovarian reserve also noted that the trials were small and the methods were often poorly described.

Our reading: CoQ10 is promising, but not proven. It is a reasonable topic to raise with a fertility doctor, especially if you are heading into IVF, rather than something to pick up at random.

Inositol (myo-inositol and D-chiro-inositol)

Inositol is popular for PCOS. It is a sugar-like compound involved in how the body responds to insulin, and insulin resistance is common in PCOS.

The review that fed into the 2023 international PCOS guideline looked at the evidence in detail. Its conclusion was that the evidence is limited and inconclusive. There were some benefits for metabolic measures, and D-chiro-inositol may help ovulation, but nothing strong enough to call it a fertility treatment. One practical point in its favor: myo-inositol seems to cause fewer stomach side effects than metformin, a common PCOS drug. That can matter if you have stopped other treatments because they upset your stomach.

Vitamin D

Low vitamin D shows up often in women having trouble conceiving, so it is natural to ask whether fixing it helps. The answer so far is “maybe, but we are not sure”.

A review of 11 cohort studies covering about 2,700 women having assisted reproduction found that women with enough vitamin D were more likely to have a live birth than those who were deficient (odds ratio about 1.33). The researchers were careful to say this shows a link, not proof of cause, and they called for randomized trials. A separate meta-analysis of five randomized trials suggested better chemical pregnancy rates in deficient women who took supplements, but again more research is needed.

What does that mean for you? If a blood test shows you are low in vitamin D, correcting it is sensible for general health. But it is not a guaranteed fertility fix.

Antioxidants as a group

This is where the research story gets interesting, and a bit messy. Cochrane, a respected group that reviews medical evidence, has looked at antioxidants for female infertility several times. The 2013 version found no evidence of benefit across 28 trials with 3,548 women. Later updates reported a possible improvement in live birth, but the 2020 update rated the evidence as very low quality and said we could not be sure.

There is also a warning attached to the Cochrane review: an editorial note flags concerns around six studies that had been retracted. That is a reminder that the research behind some supplement claims can be shaky. ASRM’s position is blunt as well: there is little evidence that vitamin-enriched diets, antioxidants or herbal remedies improve fertility in women who already ovulate normally.

Diet and lifestyle: boring, but better supported

This is where the guidance is a little more encouraging, although still not strong.

Eating pattern. A 2023 review of studies on diet before pregnancy found that the Mediterranean diet had the most consistent link with clinical pregnancy. That means plenty of vegetables, fruit, olive oil, fish and whole grains. The same review said there is not enough evidence to back any one specific diet, and most of the studies were observational, so they cannot prove cause.

The famous “fertility diet” from the Nurses’ Health Study II is a good example of the nuance. Women who followed it more closely had a much lower risk of infertility caused by ovulation problems (relative risk 0.34). But in women already having IVF, sticking to that diet was not linked to higher pregnancy or live birth rates. In other words, diet may matter most for ovulation problems, and may matter less once you are in treatment.

Body weight. ASRM says fertility is lower in women who are very thin or who have obesity. You do not need to chase a perfect number, but extreme ends of the scale can affect ovulation.

Smoking. This one is clear. A large analysis comparing about 10,900 women who smoked with about 19,100 who did not found that smokers were 60% more likely to be infertile (odds ratio 1.60). Smoking can also bring menopause forward by a year or more and raises the risk of miscarriage.

Alcohol. The research is mixed. ASRM suggests avoiding more than two drinks a day while trying, and notes there is no known safe level once you are pregnant.

Caffeine. Very high intake, above 500 mg a day (more than five cups of coffee), has been linked to lower fertility. One or two cups a day looks fine.

Fish and mercury. One study linked high blood mercury from eating a lot of seafood with infertility. That is a reason to choose lower-mercury fish, not to avoid fish.

Timing and tracking. ASRM defines the fertile window as the six days ending on the day of ovulation. Having sex every one to two days in that window gives the best chance, though two to three times a week works nearly as well, so there is no need to turn it into a chore. Ovulation test kits have been shown in a trial to shorten the time to pregnancy. Be careful with phone apps that only use the calendar, though. In one study of 949 volunteers, the best app predicted the day of ovulation correctly only 21% of the time.

How to spot a misleading fertility supplement

The fertility supplement market has a poor record. In May 2021, the FDA and the Federal Trade Commission (FTC) sent warning letters to five companies for selling supplements that claimed to cure, treat or prevent infertility and related conditions. The FDA said such products are unapproved drugs, even when they are labeled as supplements. The claims it flagged included treating luteal phase defects and ovarian cysts, preventing miscarriage and improving IVF results. Many pages also used customer testimonials about getting pregnant. Companies were given 15 working days to respond or risk legal action.

The FDA’s concern is practical, not just legal. It warned that people who rely on these products might skip treatments that actually work, such as approved drugs or assisted reproduction. It also said it had not checked whether those products work, what a safe dose is, or how they interact with other medicines.

Here are some warning signs worth remembering:

• The product says it will cure, reverse or treat infertility, PCOS, cysts or blocked tubes.

• The page is built on testimonials rather than studies.

• It talks down IVF or other medical care.

• It uses vague phrases such as “hormone balancing” or “detox” with no trial to point to.

• It offers a “proprietary blend” without listing the amount of each ingredient.

Also look for a label that lists amounts clearly and a brand that tests products through an independent lab. And check with a pharmacist if you take other medicines, because herbal products in particular can interact with them.

A simple, realistic plan

If we boiled everything above into steps, it would look like this:

1. Get checked on time. After 12 months, or 6 months if you are 35 or older, ask for a basic fertility workup for both partners.

2. Take folic acid. At least 400 micrograms daily is the one supplement recommendation with broad agreement.

3. Fix what can be fixed. Stop smoking, keep alcohol low, aim for a steady weight, and eat a Mediterranean-style diet.

4. Test before you supplement. Ask whether vitamin D, thyroid or iron levels need checking, rather than guessing.

5. Discuss extras with your doctor. CoQ10 or inositol might be reasonable in some situations, but let your doctor weigh in, especially if you have PCOS or are starting IVF.

6. Be wary of big promises. If a product sounds too good to be true, the FDA itself says it probably is.

7. Look after your mind too. Struggling to conceive is stressful. Talking to a counselor or support group is not a luxury.

The bottom line

Female infertility is common, usually has a medical cause that can be found, and often responds to proper treatment. Supplements, in contrast, sit in a gray area. Folic acid has a clear role. CoQ10, inositol and vitamin D show some promise in certain groups, but the studies are small, mixed or low in quality, and the biggest review of antioxidants came with serious caveats. No supplement has been shown to undo the effect of age.

That does not mean you should feel foolish for trying something. It means you should try things with clear eyes: check the evidence, talk to a doctor, and do not let a supplement delay the tests and treatments that carry real data. We will keep covering these ingredients one by one here at Nutrifact Guide, with the sources linked so you can judge for yourself.

References

1. World Health Organization, 1 in 6 people globally affected by infertility (2023): https://www.who.int/en/news/item/04-04-2023-1-in-6-people-globally-affected-by-infertility

2. NCBI StatPearls, Female infertility review (causes and frequency): https://www.ncbi.nlm.nih.gov/books/NBK556033/

3. American Society for Reproductive Medicine, Optimizing natural fertility: a committee opinion (2022): https://www.asrm.org/practice-guidance/practice-committee-documents/optimizing-natural-fertility-a-committee-opinion-2021

4. Endometriosis UK, PCOS officially renamed PMOS: https://www.endometriosis-uk.org/news/pcos-officially-renamed-polyendocrine-metabolic-ovarian-syndrome-pmos

5. RANZCOG, PCOS renaming to PMOS: https://ranzcog.edu.au/news/ranzcog-welcomes-polycystic-ovarian-syndrome-pcos-renaming-to-polyendocrine-metabolic-ovarian-syndrome-pmos/

6. Letrozole versus clomiphene for ovulation induction in PCOS (PPCOS II summary): https://blogs.the-hospitalist.org/content/letrozole-versus-clomiphene-ovulation-induction

7. Comparative outcomes of letrozole versus clomiphene citrate (meta-analysis): https://www.jbra.com.br/article/2988/comparative-outcomes-of-letrozol-versus-clomiphene-citrate-for-ovulation-inducti

8. UK trial registry, letrozole or clomifene for ovulation induction in PCOS: https://www.isrctn.com/ISRCTN11828358

9. ESHRE, Good practice recommendations on add-ons in reproductive medicine: https://pmc.ncbi.nlm.nih.gov/articles/PMC10628516/

10. FDA, Facts about dietary supplements: https://www.fda.gov/news-events/rumor-control/facts-about-dietary-supplements

11. American Academy of Family Physicians, FDA ruling on dietary supplement claims: https://www.aafp.org/afp/2000/0401/p2258

12. FDA, Warning letters to five companies claiming to treat infertility: https://www.fda.gov/food/hfp-constituent-updates/fda-and-ftc-send-warning-letters-five-companies-illegally-selling-dietary-supplements-claiming-treat

13. Federal Trade Commission announcement on the same warning letters: https://ftc.gov/node/73883

14. Daily Intake, FDA warns companies over unapproved fertility claims: https://www.dailyintakeblog.com/2021/05/fda-warns-companies-over-unapproved-fertility-claims/

15. CoQ10 supplementation in women having assisted reproduction, meta-analysis: https://pubmed.ncbi.nlm.nih.gov/32767206/

16. Network meta-analysis of antioxidants and adjuvants for IVF (Reproductive Biology and Endocrinology, 2023): https://doaj.org/article/481107484f9945479a27c4ac5540a14e

17. CoQ10 and diminished ovarian reserve, review: https://pmc.ncbi.nlm.nih.gov/articles/PMC11321116/

18. Inositol for PCOS, systematic review and meta-analysis for the 2023 international guideline: https://pmc.ncbi.nlm.nih.gov/articles/PMC11099481

19. Vitamin D and assisted reproductive treatment outcome, systematic review and meta-analysis: https://iro.uiowa.edu/esploro/outputs/journalArticle/Vitamin-D-and-assisted-reproductive-treatment/9983930280402771

20. Press release on the vitamin D review (association versus cause): https://www.focusonreproduction.eu/press-releases/vitamin-d-linked-with-better-live-birth-rates-in-women-undergoing-assisted-reproduction-treatment-researchers-call-for-a-randomised-controlled-trial-to-investigate/

21. Vitamin D and IVF outcomes, meta-analysis of five randomized trials: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8969598/

22. Cochrane, Antioxidants for female subfertility: https://www.cochrane.org/CD007807/

23. Cochrane review, 2020 update with editorial note: https://cochranelibrary.com/cdsr/doi/10.1002/14651858.CD007807.pub4

24. NutraIngredients, Cochrane 2013 report on antioxidants and female fertility: https://www.nutraingredients.com/Article/2013/08/05/Cochrane-Antioxidants-don-t-increase-female-fertility/

25. Assessing the influence of preconception diet on female fertility, scoping review: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10663051/

This article is for general education and is not a substitute for advice from a doctor. Supplements are not intended to diagnose, treat, cure or prevent any disease.