Fertility: A Comprehensive Guide to Male and Female Reproductive Health

KNOWLEDGE HUB

If pregnancy does not occur after 12 months of regular unprotected intercourse, or after 6 months if the woman is 35 or older, it is time for a specialist assessment of both partners: according to the World Health Organization, infertility affects about one in six people over the course of their lives. Fertility depends on the reproductive health of both partners, as well as age, hormonal balance, metabolism, and lifestyle.

In this guide, we explore how female and male fertility work, which factors affect them, and what current guidelines and research say about diet, lifestyle, and nutrients.

Reading time: 15 minutes

Last updated: October 2026

Scientific review: GP Nutraceuticals Team

Main sources: WHO 2025 guidelines, American Society for Reproductive Medicine (ASRM), 2023 international PCOS/PMOS guideline, and peer-reviewed literature

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Fertility at a glance

Fertility is one of the most sensitive indicators of overall health. It depends not only on the reproductive organs, but on the interaction between hormonal balance, metabolism, gamete quality, and lifestyle, in both women and men.

For this reason, when pregnancy does not occur, both partners should always be assessed: a male factor is present in about half of cases.

Key points

The guide’s central message in five points: fertility concerns both partners, depends above all on age and factors that can be addressed, and should be assessed early when pregnancy is delayed.

• Infertility affects about one in six people of reproductive age.
• Age is the most well-documented factor: in women, the decline in fertility becomes more evident after age 35.
• The fertile window lasts about six days and ends on the day of ovulation.
• Weight, smoking, alcohol, and metabolic health are modifiable factors that affect reproductive function.
• Evidence for supplements is still limited: the only established exception is folic acid before conception, recommended for the health of the unborn baby.

What you’ll find in this guide

The guide starts with the biological basics of fertility, moves on to fertile days and the factors that affect fertility, and concludes with nutrients, supplements, and answers to frequently asked questions.

• What is fertility and when is it considered infertility?
• What are the fertile days and how can you increase your chances of getting pregnant?
• How female fertility works.
• How male fertility works.
• What affects fertility.
• The role of oxidative stress.
• Nutrients and supplements: evidence and claims.
• Frequently asked questions.

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This guide is for informational and educational purposes only and is not a substitute for advice from a doctor or other qualified healthcare professionals.

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What is fertility, and when is infertility discussed?

Fertility is the biological ability of an individual or couple to conceive a pregnancy through the union of a viable egg and sperm, under conditions favorable to fertilization, implantation of the embryo in the uterus, and its development.

Fertility can change over the course of life: it is not an unchanging trait, but a dynamic function that depends on age, health, hormonal balance, lifestyle, and environmental factors. It is also a characteristic of the couple: the ability to conceive arises from the interaction between female and male reproductive health.

How do fertilization and conception occur?

Conception requires a complex sequence of events:

• development and maturation of gametes;
• ovulation and spermatogenesis;
• fertilization;
• embryo transport;
• implantation in the endometrium;
• maintenance of the early stages of pregnancy.

An abnormality in just one of these steps can reduce the chances of conception.

When infertility is discussed

Infertility is defined as a couple's inability to achieve pregnancy after 12 months or more of regular unprotected intercourse, according to the World Health Organization. The American Society for Reproductive Medicine (ASRM) recommends starting an evaluation after 12 months if the woman is under 35, and after 6 months if she is 35 or older, or sooner if there are known conditions that may affect fertility.

According to WHO estimates, infertility affects around 17.5% of adults at some point in their lives, or about one in six people, with similar rates in high- and low-income countries. A male factor is involved in about half of cases.

What are the causes of female and male infertility?

Fertility problems can affect the woman, the man, or both. The most common causes of female infertility are ovulation disorders, such as PCOS, problems with the fallopian tubes, endometriosis, and age-related decline in ovarian reserve. Causes of male infertility include abnormalities in sperm production or quality, varicocele, infections, and hormonal imbalances. In some cases, no specific cause is found despite investigations, and the infertility is described as unexplained.

There is no single fertility test. For women, the evaluation includes checking ovulation, measuring AMH, an ultrasound, and assessing whether the fallopian tubes are open; for men, a semen analysis. Based on the results, a specialist may suggest options ranging from advice on timing intercourse during the fertile window to assisted reproductive techniques.

The WHO’s first global guidelines

In November 2025, the WHO published its first global guideline on the prevention, diagnosis, and treatment of infertility, with 40 recommendations. Key points include lifestyle changes (healthy eating, physical activity, and quitting smoking) for people trying to conceive; diagnostic pathways that assess both the woman and the man; stepwise treatments, from advice on the fertile window to insemination or in vitro fertilization; and access to psychological support for everyone involved.

What are the fertile days, and how can you increase your chances of getting pregnant?

How long does the fertile window last?

The chance of conception is concentrated in the fertile window, a period of about 5-6 days per cycle: the five days before ovulation and the day of ovulation itself. Sperm can survive for a few days in the female reproductive tract, while the egg remains viable for only a few hours. This is why the chance drops quickly after ovulation. In a classic study published in the New England Journal of Medicine, the chance ranged from about 10% with sex five days before ovulation to about 33% on the day of ovulation.

How do you calculate your fertile days and identify ovulation?

Ovulation generally occurs about 14 days before the next period. So, in a regular 28-day cycle, it falls around day 14, and the fertile days are roughly days 9 to 14. Compared with a 28-day cycle, ovulation shifts accordingly in longer or shorter cycles, and even with a regular cycle it can vary by a few days from month to month.

Methods based on fertility awareness can help identify the fertile window:

• track the length of your menstrual cycle for a few months;
• use ovulation tests, which detect the LH hormone surge in urine 24-36 hours before ovulation;
• observe cervical mucus, which becomes more abundant, clear, and stretchy on fertile days.

How can you increase your chances of getting pregnant?

There’s no need to schedule sex precisely: regular sex every two or three days covers the fertile window well and reduces anxiety about getting the “right day.” In a young, healthy couple, the chance of getting pregnant in a single cycle is about 20%, and most couples manage to get pregnant within the first year.

A healthy lifestyle helps improve fertility for both partners: no smoking, little alcohol, a healthy weight, and regular physical activity. Anyone hoping to have a baby should start taking folic acid at least one month before trying to conceive. If pregnancy does not occur after 12 months of regular unprotected sex, or after 6 months if the woman is 35 or older, it is time to consult a fertility specialist.

How does female fertility work?

Female fertility depends on the interaction between ovarian function, hormonal balance, egg quality, endometrial receptivity, and the integrity of the reproductive system.

During each menstrual cycle, the hypothalamic-pituitary-ovarian axis coordinates the maturation of ovarian follicles. Usually, a single follicle completes development and reaches ovulation, releasing an egg that can be fertilized. For conception to occur, regular ovulation, a good-quality egg, open fallopian tubes, fertilization, a receptive endometrium, and proper early embryonic development are needed.

Age and fertility: why does a woman's fertility decline after 35?

Age is the best-documented factor. A woman is born with a defined ovarian reserve, which gradually decreases: over the years, both the number and quality of eggs decline, and chromosomal abnormalities become more common. A woman's most fertile years are between 20 and 30; fertility declines gradually after 30, more rapidly after 35, and even more so after 37. According to the American Society for Reproductive Medicine, at age 30 the chance of conceiving in a single cycle is about 20%; at age 40 it drops below 5%. Between 45 and 50, spontaneous pregnancy is rare, even though menopause occurs at around age 50 on average. However, the decline in fertility varies greatly from woman to woman.

Ovarian reserve: what does AMH measure?

A woman's fertility also depends on her ovarian reserve. Specialist assessments include measuring anti-Müllerian hormone (AMH) and counting antral follicles by ultrasound. AMH is a good indicator of ovarian reserve, or the number of follicles still present, but it does not measure egg quality or, on its own, predict the likelihood of spontaneous pregnancy.

Endocrine balance and metabolism

Fertility and metabolism are closely linked. Ovarian function is influenced by the balance of reproductive hormones, insulin sensitivity, nutritional status, body composition, and inflammation. Thyroid disorders, obesity, being underweight, and insulin resistance can interfere with regular ovulation.

PMOS: the new name for polycystic ovary syndrome

Polycystic ovary syndrome is one of the most common endocrine-metabolic conditions in reproductive-age women: it affects about one in eight women and is a common cause of infertility due to failure to ovulate.

In May 2026, after a 14-year international process, the condition officially received a new name: polyendocrine-metabolic ovarian syndrome (PMOS), replacing polycystic ovary syndrome (PCOS). The change, published in The Lancet and supported by over 50 scientific societies and patient associations, is based on a specific finding: women with this condition do not actually have an increased number of abnormal ovarian cysts; instead, hormonal and metabolic factors, such as insulin resistance, are central. The new name will be fully adopted in the update to the international guideline scheduled for 2028, following a three-year transition period. As a result, both acronyms will continue to appear in medical reports and the literature.

Symptoms may include irregular cycles, ovulatory dysfunction, signs of androgen excess, and metabolic disorders. Diagnosis and management require specialist assessment.

How does male fertility work?

Male fertility depends on the ability to produce functional, genetically intact sperm in adequate numbers.

This process, spermatogenesis, takes place in the seminiferous tubules of the testes and takes about 70-75 days. It is regulated by a balance of hormones, cellular metabolism, and environmental factors. That is why the sperm produced today reflect, at least in part, conditions over the previous three months. This is also why the effects of lifestyle changes on semen are assessed after a few months.

What does a semen analysis assess?

A semen analysis is the basic test for male fertility assessment and should be performed according to the World Health Organization’s Laboratory Manual criteria (sixth edition, 2021). Among other things, it measures:

• sperm concentration and total count;
• progressive and total motility;
• morphology;
• vitality;
• ejaculate volume.

It is the starting point, but it does not fully describe fertility potential: men with normal results may have difficulty conceiving, while others with mild abnormalities achieve a spontaneous pregnancy. Results should always be interpreted in the context of the couple’s medical history.

Sperm quality and DNA fragmentation

In recent years, attention has shifted from sperm count to sperm biological quality. A functional sperm cell must have an intact membrane, efficient mitochondria, which provide the energy for movement, and stable, well-compacted DNA.

Sperm DNA fragmentation refers to breaks in genetic material, caused, for example, by oxidative stress. Several studies have associated it with lower semen quality and possible effects on reproductive outcomes, but it is not a first-line test: a specialist may request it in selected situations, such as unexplained infertility, recurrent miscarriages, or repeated unsuccessful attempts at medically assisted reproduction.

Age and male fertility

Men generally retain their reproductive capacity for longer, but male fertility also changes with age: several studies have observed a gradual decline in motility and morphology and a possible increase in DNA fragmentation at older ages, especially after 45-50. However, fertility declines more gradually than in women and varies greatly from person to person: there is no age beyond which it is lost.

What affects male and female fertility?

In most cases, there is not a single cause, but a combination of different factors. Factors recognized in scientific literature include:

• age;
• hormonal balance and metabolic health;
• body weight;
• nutrition and physical activity;
• sleep quality;
• smoking and alcohol;
• untreated sexually transmitted infections;
• exposure to environmental substances;
• psychological and physical stress;
• any coexisting conditions.

The importance of each factor varies from person to person, which is why assessment always requires a personalized approach.

Nutrition

No diet can guarantee conception, but dietary patterns rich in vegetables, fruit, whole grains, legumes, fish, extra virgin olive oil, and nuts are associated with better metabolic health, which in turn supports reproductive function. By contrast, high consumption of ultra-processed foods, added sugars, and low-quality fats can contribute to metabolic and inflammatory changes.

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Did you know? Fertility and overall health

Reproductive health often reflects overall health. Nutrition, physical activity, sleep, and metabolic well-being matter not only for fertility but also for preventing many chronic diseases.

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Body weight

Both underweight and overweight can disrupt hormonal balance. In women, they can make ovulation irregular; in men, they can affect testosterone levels and some semen parameters. The goal is not an "ideal" weight, but a metabolic state that supports overall health.

Physical activity and sleep

Regular, moderate physical activity helps maintain insulin sensitivity, body composition, and cardiovascular health. In contrast, both a sedentary lifestyle and very intense, prolonged training can disrupt hormonal balance in people who are predisposed. Getting enough sleep and keeping a regular schedule also contribute to the proper functioning of the endocrine systems involved in reproduction.

Smoking, alcohol, and environmental factors

Smoking is one of the risk factors addressed by the WHO 2025 guideline, along with untreated sexually transmitted infections, which can cause infertility by damaging the fallopian tubes. Smoking and excessive alcohol consumption negatively affect fertility: they are associated with poorer egg and semen quality. Some occupational or environmental exposures, such as pesticides, solvents, heavy metals, and endocrine disruptors, may also affect fertility and are being studied: the effect depends on the intensity and duration of exposure and individual characteristics.

What role does oxidative stress play in fertility?

Cells constantly produce reactive oxygen species (ROS), molecules that are essential in small amounts: in sperm, for example, they play a role in maturation and the ability to fertilize. The body has antioxidant systems that maintain this balance.

When ROS production exceeds the body's defenses, this is called oxidative stress. In men, it can damage sperm membranes, mitochondria, and DNA; in women, it has been associated with changes in the follicular environment, egg quality, and the early stages of embryonic development. It is one of the most studied mechanisms in reproductive medicine and could explain some cases of male infertility with no apparent cause.

However, knowing that oxidative stress is involved does not mean that taking antioxidants improves fertility: that is a different question, and clinical studies have yet to provide clear answers (see the section on supplements).

Key points about oxidative stress

• It is not a disease, but a biological imbalance.
• Small amounts of ROS are necessary for normal cell function.
• Excess can interfere with several reproductive processes.
• Smoking, obesity, alcohol, and certain environmental exposures increase oxidative stress; diet and lifestyle help maintain the balance.

Can nutrients and supplements increase fertility?

Many nutrients have been studied for their possible role in reproductive health. To make sense of the evidence, two separate questions need to be asked: what the studies suggest and what regulations allow to be stated on the label.

Scientific evidence and regulatory claims are two different things. A permitted label claim describes a physiological function recognized by an authority and does not demonstrate that a product helps achieve pregnancy. Likewise, a favorable study alone does not authorize a claim.

What the studies suggest

Nutrient	What the studies suggest	Notes
Folic acid	Before conception, it reduces the risk of neural tube defects in the baby: the Italian National Institute of Health recommends 0.4 mg daily from at least one month before conception through the third month of pregnancy. It is not a treatment for infertility: in men, high-dose folic acid and zinc did not improve semen quality or live births in a large randomized trial (2,370 men).	Recommended for all women trying to conceive.
Myo-inositol	In women with PCOS, the review underpinning the 2023 international guideline indicates possible benefits for some metabolic parameters, but limited and inconclusive evidence for reproductive outcomes, including ovulation. The guideline allows its use based on individual preferences.	Well tolerated; mild gastrointestinal symptoms.
Antioxidants in men (coenzyme Q10, L-carnitine, vitamins C and E, selenium, zinc, and combinations)	The 2022 Cochrane review (90 studies, over 10,000 men) indicates a possible increase in pregnancies and live births, with very low certainty: after excluding studies at high risk of bias, the effect on live births is no longer demonstrated. The randomized MOXI trial found no benefits for semen parameters or live births.	Possible mild gastrointestinal symptoms.
Coenzyme Q10 in women	In women with diminished ovarian reserve undergoing in vitro fertilization, a 2024 meta-analysis of 6 randomized studies suggests more clinical pregnancies; studies are small and methodologically limited.	Data relate to assisted reproduction, not spontaneous conception.
Vitamin D	Observational studies associate adequate levels with better reproductive outcomes, but the benefits of supplementation for fertility have not been demonstrated.	Correcting a possible deficiency remains beneficial for overall health.
Astaxanthin	Few clinical studies, particularly on semen parameters; preliminary data.	More extensive studies are needed.

Two elements help interpret these data:

• many studies measure laboratory parameters, such as motility or DNA fragmentation, rather than births, which are the outcome that really matters;
• formulations and doses vary considerably from one study to another: findings on one ingredient cannot automatically be applied to a product.

What a supplement can claim

Vitamins and minerals. Health claims are assessed by EFSA and authorized by Regulation (EU) 432/2012. They describe physiological functions, not the ability to promote pregnancy:

• zinc contributes to normal fertility and reproduction, the maintenance of normal testosterone levels in the blood, and the protection of cells from oxidative stress;
• selenium contributes to normal spermatogenesis and the protection of cells from oxidative stress;
• folate contributes to the growth of maternal tissues during pregnancy, normal amino acid synthesis and the process of cell division;
• vitamins C and E contribute to the protection of cells from oxidative stress.

Folic acid during pregnancy. Regulation (EU) 1135/2014 also authorizes a risk-reduction claim: folic acid supplementation increases the mother’s folate levels, and low levels are a risk factor for neural tube defects in the fetus. This claim is permitted for products providing at least 400 µg per day, taken from at least one month before to three months after conception.

Other compounds. Myo-inositol, coenzyme Q10, L-carnitine, alpha-lipoic acid and astaxanthin have no authorized health claims in the European Union: their presence in a product does not prove that they are effective.

Frequently asked questions about fertility

Here you’ll find brief answers to the most common questions about fertility, infertility and pregnancy. Each topic is covered in more detail in the preceding sections of this guide.

How long should you wait without a pregnancy before seeing a specialist?

Under 35, after 12 months of regular unprotected sex without a pregnancy; from age 35 onward, after just 6 months. Seek advice sooner if there are known conditions: very irregular or absent periods, endometriosis, previous pelvic surgery or infections, suspected semen abnormalities, or other endocrine and metabolic disorders. Both partners should be evaluated.

At what age does fertility decline?

Female fertility begins to decline gradually after age 30, more noticeably after 35 and even more so after 37, due to a decrease in the number and quality of eggs. In men, the decline is more gradual and becomes more noticeable after age 45-50.

What is the probability of getting pregnant after 40 and at 45-47?

It decreases significantly. According to the American Society for Reproductive Medicine, at age 40 the chance of conceiving in a single cycle is under 5%. After age 45, spontaneous pregnancy using one's own eggs is rare and the risk of miscarriage is much higher; even with assisted reproduction using one's own eggs, the chances of success are low, and egg donation is often used at this age. So if you want to have a baby after 40, it is helpful to talk to a fertility specialist early.

On average, how long does it take to have a baby?

For a young, healthy couple, the chance of conceiving in any given cycle is about 20%. When the woman is under 40, more than 80% of couples conceive within the first year; among those who do not conceive after a year of trying, about half achieve pregnancy in the second year, so that more than 90% conceive within two years of trying. For women over 35, it tends to take longer.

Can you get pregnant with an irregular menstrual cycle?

Yes, but ovulation is less predictable and may occur less often, making it harder to calculate fertile days. Very irregular or absent periods may indicate an ovulation disorder, such as PMOS or a thyroid problem. In these cases, it is helpful to talk to a doctor without waiting 12 months.

What is AMH?

It is anti-Müllerian hormone, produced by ovarian follicles in the early stages of development. It indicates ovarian reserve, meaning how many follicles are still present in the ovaries, but it does not measure egg quality and cannot on its own predict the likelihood of spontaneous pregnancy.

Are PCOS and PMOS the same thing?

Yes. Since May 2026, polycystic ovary syndrome (PCOS) has officially been called polyendocrine-metabolic ovarian syndrome (PMOS). The new name highlights the hormonal and metabolic aspects of the condition and will be fully adopted by international guidelines in 2028; in the meantime, both abbreviations will be used.

What is sperm DNA fragmentation?

It indicates the presence of breaks in sperm genetic material. It is not a routine test: a specialist may request it in selected cases, such as unexplained infertility, recurrent miscarriages, or repeated failures with assisted reproduction.

Do supplements increase fertility?

The evidence is still limited. For antioxidants in humans, the Cochrane review indicates a possible benefit with very low certainty, which has not been confirmed by the most rigorous studies; for myo-inositol in PMOS, evidence on reproductive outcomes is limited. The only supplement consistently recommended is folic acid before conception, for the health of the baby.

When should you start taking folic acid?

The Italian Network for the Promotion of Folic Acid, coordinated by the Italian National Institute of Health, recommends 0.4 mg per day in addition to the diet for all women planning or not ruling out a pregnancy, starting at least one month before conception and continuing until the third month of pregnancy. In certain situations, a doctor may recommend different doses.

Can fertility be improved?

Age and some genetic conditions cannot be changed, but many factors can: quitting smoking, limiting alcohol, maintaining a healthy weight, exercising regularly, getting enough sleep, and managing any health conditions can help preserve reproductive function.

Are fertility and fecundity the same thing?

Not exactly. Fertility refers to the biological potential to conceive, while fecundity refers to the probability or outcome of conception over a given period. In everyday language, the two terms are often used interchangeably.

Are infertility and sterility the same thing?

No. Infertility refers to difficulty achieving pregnancy after a period of regular unprotected sex, or the need for medical assistance to conceive. Sterility refers to a condition in which natural conception is not biologically possible. In clinical practice, the term infertility is used predominantly.

In summary

Fertility is a complex balance involving reproductive health, endocrine function, metabolism, and lifestyle, and it always concerns both partners. Age remains the most important factor, but smoking, weight, alcohol, and metabolic health are factors that can be addressed.

If pregnancy has not occurred after 12 months, or after 6 months for those over 35, it is time for both partners to have a specialist evaluation.

Evidence for supplements is still limited and should be considered separately from the health claims permitted on labels. Folic acid before conception is the only well-established recommended supplement.

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The GP Nutraceuticals nutraceutical approach

GP Nutraceuticals develops formulations inspired by the latest scientific knowledge, selecting high-quality ingredients and paying particular attention to composition, dosages, and raw materials.

Among the formulations dedicated to reproductive health:

GoFertil® – a dietary supplement for men combining Carnipure® L-carnitine, acetyl-L-carnitine, arginine, coenzyme Q10, glutathione, and astaxanthin with vitamins and minerals. Zinc contributes to normal fertility and reproduction; selenium contributes to normal spermatogenesis; vitamin C, vitamin E, zinc, and selenium contribute to the protection of cells from oxidative stress.

GoFertil Pink® – a dietary supplement for women combining myo-inositol, alpha-lipoic acid, coenzyme Q10, glutathione, and astaxanthin with vitamins and minerals, including 400 µg of folic acid. Zinc contributes to normal fertility and reproduction; vitamins C, E, and B2, zinc, and selenium contribute to the protection of cells from oxidative stress.

Supplements should not be considered substitutes for a varied and balanced diet and a healthy lifestyle. If undergoing assisted reproduction or currently receiving treatment, it is advisable to consult a specialist.

For more information on composition and use, please consult the respective product information sheets.

Scientific sources and references

This guide was prepared based on the main international guidelines and peer-reviewed scientific literature available at the time of the update.

Guidelines and consensus documents

1. World Health Organization. Guideline for the prevention, diagnosis, and treatment of infertility. 2025. who.int
2. Practice Committee of the American Society for Reproductive Medicine. Definition of infertility: a committee opinion. 2023. asrm.org
3. Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. J Clin Endocrinol Metab. 2023. PMID: 37580314
4. World Health Organization. WHO laboratory manual for the examination and processing of human semen. 6th ed. 2021.
5. Endocrine Society. Polyendocrine Metabolic Ovarian Syndrome: new name to improve diagnosis and care of condition affecting 170 million women worldwide. Press release, May 12, 2026. endocrine.org
6. Italian National Institute of Health – EpiCentro. Folic acid: recommendation for the prevention of birth defects. epicentro.iss.it
7. American Society for Reproductive Medicine. Age and Fertility: a guide for patients. ReproductiveFacts.org.
8. National Institute for Health and Care Excellence (NICE). Fertility problems: assessment and treatment (CG156). 2013, updated 2017.

Epidemiology, physiology, and mechanisms

9. Cox CM, Thoma ME, Tchangalova N, et al. Infertility prevalence and the methods of estimation from 1990 to 2021: a systematic review and meta-analysis. Hum Reprod Open. 2022. PMID: 36483694
10. Wilcox AJ, Weinberg CR, Baird DD. Timing of sexual intercourse in relation to ovulation: effects on the probability of conception, survival of the pregnancy, and sex of the baby. N Engl J Med. 1995;333(23):1517-1521. PMID: 7477165
11. Forslund M, Melin J, Joham A, et al. Recent advances in polyendocrine metabolic ovarian syndrome, formerly polycystic ovary syndrome, with emphasis on endocrine and metabolic dysfunction and cardiovascular risk. J Intern Med. 2026. PMID: 42669621
12. Agarwal A, Baskaran S, Parekh N, et al. Male infertility. Lancet. 2021;397(10271):319-333. PMID: 33308486
13. Agarwal A, Aponte-Mellado A, Premkumar BJ, et al. The effects of oxidative stress on female reproduction: a review. Reprod Biol Endocrinol. 2012;10:49. PMID: 22748101

Nutrients and supplements

14. de Ligny W, Smits RM, Mackenzie-Proctor R, et al. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022;5:CD007411. PMID: 35506389
15. Steiner AZ, Hansen KR, Barnhart KT, et al. The effect of antioxidants on male factor infertility: the Males, Antioxidants, and Infertility (MOXI) randomized clinical trial. Fertil Steril. 2020. PMID: 32111479
16. Schisterman EF, Sjaarda LA, Clemons T, et al. Effect of folic acid and zinc supplementation in men on semen quality and live birth among couples undergoing infertility treatment: a randomized clinical trial. JAMA. 2020;323(1):35-48. PMID: 31910279
17. Fitz V, Graca S, Mahalingaiah S, et al. Inositol for polycystic ovary syndrome: a systematic review and meta-analysis to inform the 2023 update of the international evidence-based PCOS guidelines. J Clin Endocrinol Metab. 2024. PMID: 38163998
18. Lin G, Li X, Jin Yie SL, Xu L. 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

Regulatory framework

19. Commission Regulation (EU) No 432/2012 on permitted health claims made on food products.
20. Commission Regulation (EU) No 1135/2014 on the authorization of a health claim concerning folic acid and the reduction of the risk of neural tube defects. eur-lex.europa.eu

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Update history

Here we report revisions to the guide to make transparent how it is updated in light of new scientific evidence and guidelines.

Version 1.1 – October 2026

Scientific review: new name PMOS, first WHO infertility guideline (2025), ASRM 2023 definition, fertile window, section on nutrients and supplements distinguishing evidence from claims, expanded sources.

Version 1.0 – July 2026

First publication of the guide.

This page will be updated periodically to incorporate new scientific evidence, revisions to international guidelines, and research developments in reproductive medicine and nutraceuticals.