Fertility Nutrition After 12 Months Trying

If the two of you have been trying for twelve months without a pregnancy, you've just crossed the clinical threshold that formally defines infertility under the current NICE fertility guideline (NG257, published March 2026) and the ESHRE 2023 guideline on unexplained infertility.^1,2 That word — infertility — can feel like a punch to the gut, even when your GP says it in a perfectly matter-of-fact way. But hitting this milestone doesn't mean something is broken beyond repair. It means your bodies are telling you it's time to be more intentional — and nutrition is one of the most meaningful places the two of you can start.

Here's something most couples aren't told: the gap between hitting the 12-month mark and the first clinical intervention can be surprisingly long. NHS waiting lists often stretch for several months before any active treatment begins. That waiting period is actually when a well-designed nutrition protocol matters most — it's not lost time, it's biological runway. The final phase of egg development takes approximately 85–90 days, and sperm complete their development cycle in approximately 72–74 days.^3,4 So any supplement you start today is primarily influencing the gametes you'll ovulate or ejaculate around three months from now.

This article walks you through what the evidence genuinely supports — and what it doesn't — for couples at this stage. Each recommendation is graded by the strength of the underlying research, separated by partner, and mapped to the three phases most couples pass through: active investigation, assisted conception, and IVF where relevant. None of this replaces personalised clinical advice — before starting any new supplement, particularly if you take prescription medication, discuss it with your GP or fertility clinician.

What does the 12-month milestone actually mean?

Once you've been having unprotected intercourse for 12 months without conceiving, you meet the WHO definition of infertility — regardless of whether anyone has identified a specific cause yet.¹ Roughly one in seven UK couples is in the same place, so if it feels like everyone around you is conceiving easily, the statistics genuinely aren't on their side. And the most common outcome of initial investigation is “unexplained” infertility — meaning semen analysis, tubal patency, and ovulatory testing all come back normal.² That can feel more frustrating than getting a clear answer, we know — but it also means there's no structural barrier standing between you and the difference nutrition can make.

At this point the clinical pathway typically moves from watchful waiting to active investigation:

• Semen analysis for the male partner
• Mid-luteal progesterone to confirm ovulation
• AMH or antral follicle count for ovarian reserve
• Tubal patency test (HSG or HyCoSy) for the female partner

The NHS funded pathway varies by local Integrated Care Board but usually requires 12 months of trying before IUI or IVF referral is considered. While you wait, you've got a meaningful window in which nutrition can genuinely influence the gametes that will eventually be used — whether you conceive naturally or those eggs and sperm are retrieved for IVF.

Why does the 90-day biology lesson matter for supplement timing?

This genuinely surprised us when we first learned it, and it's one of the most important things for you to understand at this stage. By the time an egg is ovulated, it has spent its final ~85–90 days progressing through antral follicle development — and across that whole window it is highly sensitive to oxidative stress and mitochondrial energy status.³ Sperm complete their development cycle in approximately 72–74 days, with an additional 2–10 days of epididymal transit.⁴

What does that actually mean for you? A supplement started today isn't influencing next week's ovulation or next week's ejaculate. It's influencing the egg you'll ovulate in about three months and the sperm that will be ejaculated in about ten weeks.

For any supplement protocol to have a fair chance of helping you, you'll want at least three months of consistent daily intake before the first cycle in which its effect could show up. Starting a protocol in the same month as an IUI cycle gives you almost none of the biological effect you're hoping for. This is why fertility clinicians increasingly recommend that you begin targeted nutritional support 3 to 6 months before any planned treatment cycle — and why starting today, even if your treatment date still feels far away, is genuinely worth doing.

What should a woman’s advanced nutrition protocol include at this stage?

Let's look at what the research actually tells you. The 2020 Cochrane review of antioxidant supplementation in women with subfertility (63 randomised trials, 7,760 women) concluded that antioxidants may be associated with increased clinical pregnancy rates compared with placebo, though the overall certainty of evidence was rated low.⁵ The compounds with the most consistent track record across those trials were CoQ10, N-acetylcysteine, melatonin, myo-inositol, and combinations of vitamins C and E with selenium.

Before starting any of these, discuss the plan with your GP or fertility clinician, particularly if you're already taking prescription medication.

CoQ10. CoQ10 has built up some of the strongest single-compound evidence in this whole space, and it's where many fertility nutritionists will start you. A 2024 meta-analysis of six RCTs in women with diminished ovarian reserve undergoing IVF found that CoQ10 pretreatment (200–600 mg/day over 60–90 days) was associated with improved oocyte quality indicators and higher clinical pregnancy rates.⁶ A starting dose of 200 mg/day is reasonable for general preconception use; if diminished ovarian reserve has been confirmed, ask your fertility clinician about moving up towards the higher trial doses (up to 600 mg/day).

Myo-inositol. At 2–4 g/day, myo-inositol has a meaningful evidence base if you have PCOS, with meta-analyses showing improvements in insulin sensitivity, fasting insulin, and androgen markers.⁷ One thing we'd want you to know: a substantial portion of that evidence base comes from studies authored by researchers affiliated with inositol manufacturers, so it's worth weighing the findings with that in mind. And if you're already taking metformin for PCOS, talk to your GP or fertility clinician before adding myo-inositol — the two have overlapping insulin-sensitising mechanisms and your metformin dose may need adjustment.

Folate. If you're planning to conceive, folate at 400–800 µg/day (as folic acid or methylfolate) is non-negotiable. The MTHFR C677T variant reduces enzyme activity by approximately 35% (heterozygous) or 70% (homozygous), but routine MTHFR genotyping isn't recommended by ACMG, ACOG, or current UK preconception guidance for the general population.⁸ If you already know you carry C677T, methylfolate (the active, already-methylated form) is a reasonable, low-risk choice and is increasingly the default in preconception products. Otherwise, the standard 400 µg/day NHS-recommended folic acid dose remains the cornerstone of routine preconception care.

Vitamin D. Observational data consistently links vitamin D status to assisted-reproduction outcomes: the Chu 2018 meta-analysis found higher clinical pregnancy and live birth rates in women classified as “replete” (>75 nmol/L) versus deficient/insufficient.⁹ Current UK SACN and NHS guidance treats serum 25(OH)D above 50 nmol/L as sufficient; if your levels sit above that, it's best to interpret them with clinician input rather than chase a higher number on your own.

Omega-3. For you, EPA/DHA at up to 1 g/day is supported by observational and some trial data (some clinical protocols use higher doses up to 2 g, but the standard evidence-based recommendation we'd suggest is up to 1 g combined), including a 2022 analysis of data from 900 women in a prospective cohort that found omega-3 supplement use was associated with a 1.51-fold increase in the probability of conceiving (95% CI 1.12–2.04), with the usual caveat that omega-3 users tend to be healthier overall.¹⁰

So what does a well-constructed protocol look like for you in practice? For women at your stage, it combines folate (folic acid or methylfolate), vitamin D, CoQ10, omega-3, and a broad-spectrum antioxidant base (vitamin E, vitamin C, zinc, selenium). This is the logic behind why we'd point you toward a fertility-specific formulation built around the 3-month gamete-development window rather than a generic prenatal vitamin.

What should a man’s advanced nutrition protocol include at this stage?

Here's something that doesn't get said enough to you — and we want to say it plainly: a male factor is a primary or contributing cause in approximately 50% of couple infertility cases.¹¹ That's half. Yet in so many couples like yours, only the woman ends up changing her routine. The 2022 Cochrane review of antioxidants for male subfertility (90 trials, 10,303 men) concluded that antioxidants probably increase live birth and clinical pregnancy rates compared with placebo, with evidence certainty rated low-to-moderate.¹²

The best-studied individual compounds are:

• L-carnitine (2–3 g/day): improved sperm motility in a 2021 meta-analysis of seven RCTs (621 men)¹³
• CoQ10 (200–400 mg/day): consistent improvements in sperm concentration and motility across trials in a 2021 systematic review¹⁴
• Zinc (15–30 mg/day): required for spermatogenesis; deficiency is associated with reduced sperm count. Long-term supplementation above 25 mg/day may reduce copper absorption; a small copper supplement (1–2 mg/day) can offset this
• Selenium (100–200 µg/day): supports sperm structural integrity
• Vitamin E (100–400 IU/day) combined with vitamin C: reduces sperm DNA fragmentation. High-dose vitamin E may increase bleeding risk — discuss with your doctor if taking blood-thinning medication

The 2022 Cochrane update reported that combination antioxidant regimens showed effects on clinical pregnancy and live birth rates comparable to — and in several comparisons larger than — single-compound regimens. This is the rationale we'd give you for choosing multi-ingredient male formulations over isolated high-dose single ingredients.¹²

And it's not just about the supplements. Alongside whatever protocol you're on, you'll want to tackle the modifiable lifestyle factors too: scrotal heat exposure (laptops on laps, hot baths), tobacco, and heavy alcohol use all independently impair sperm parameters and will blunt any benefit the supplements would otherwise give you.

How does nutrition integrate with active clinical treatment?

One of the questions we hear most often from couples reaching this stage is whether you have to stop everything the moment treatment starts. The short answer: no — most targeted fertility nutrients are safe to continue through IUI and IVF cycles. But there are three scenarios in which your fertility clinic may ask you to pause or adjust:

• High-dose vitamin E (above 400 IU/day) and fish oil in therapeutic doses may increase bleeding time and are sometimes paused for 7–10 days around egg retrieval.
• High-dose vitamin C (above 2 g/day) has theoretical interactions with some ovarian stimulation protocols and is usually not needed at those doses anyway.
• Melatonin at 3 mg/night should be discussed with the clinic because some protocols use or avoid it depending on the stimulation regimen.

No reputable clinic will ask you to stop folate, vitamin D, CoQ10 at standard fertility doses, zinc, or selenium — keep taking them through the cycle. One practical tip from couples who've been through this: bring a written list of everything the two of you are taking, with doses, to your first consultation and again before any IVF stimulation begins. It saves time and spares you the awkward “I think it was 200-something milligrams” conversation when you're already nervous.

What does a phase-based protocol look like in practice?

We know this can feel overwhelming for you, so here's a clear map. The table below lays out the protocol across three phases most couples like yours encounter between month 12 and the first treatment cycle. Evidence strength refers to the weight of RCT and meta-analytic data supporting each recommendation we'd make to you.

Evidence-strength key:

• Strong: multiple RCTs and at least one meta-analysis consistently showing benefit, with plausible mechanism and low safety concern.
• Moderate: several positive trials with some mixed results, or one large meta-analysis with low-to-moderate certainty.
• Preliminary: small trials, observational data, or indirect biological rationale only.

How should you grade the evidence behind each supplement?

Not every recommendation in the protocol above carries equal weight, and being honest about that matters. Understanding the grading helps you avoid over-relying on a single headline finding and interpret the conflicting results you'll inevitably encounter online.

• Folate: Strong. The evidence for periconceptional folate in preventing neural-tube defects is extensive and well-replicated.
• Vitamin D: Strong-to-moderate. Meta-analytic evidence is consistent for the association with ART outcomes, but RCT evidence on supplementation is less consistent, and the causal direction is still debated.
• CoQ10 (both partners): Strong-to-moderate. The mitochondrial mechanism is robust and clinical trial results are mostly positive, though sample sizes are smaller than we'd ideally like to see.
• Combined antioxidant therapy (both partners): Moderate. Meta-analyses consistently show benefit but rate evidence certainty as low-to-moderate due to differences in trial designs.
• Myo-inositol for PCOS: Strong within that population, with the conflict-of-interest caveat noted above.
• L-carnitine in men: Moderate.
• Omega-3 (both partners): Moderate.
• Melatonin and NAC in women: Preliminary-to-moderate — worth discussing with a clinician.

When should you escalate from nutrition to clinical intervention?

We want to be really clear with you about this: nutrition isn't a replacement for investigation. Once you've passed the 12-month mark, the two of you should both have had a full workup — semen analysis, ovulation confirmation, ovarian reserve markers, and tubal assessment — whatever supplement protocol you're on.

If any of your investigations come back with an abnormal result (tubal blockage, severe male factor, anovulation, or low AMH for age, for example), nutrition becomes a complement to your specific clinical plan — never a reason for you to delay treatment.

Current UK guidance (NICE NG257, 2026) recommends specialist referral after 12 months of unsuccessful trying for women under 36, with earlier referral (after 6 months) considered for women aged 36 and over or where a clinical factor is already suspected. NHS-funded IVF eligibility for couples with unexplained infertility typically follows a further period of trying and varies by local Integrated Care Board. Your GP can explain the specific pathway in your area.¹

If you've been trying for 18 months with a normal workup, if you're over 35, or if either partner has abnormal results, escalation to IUI or IVF should not be deferred to “give the supplements more time.” The ~90-day biology still applies — but it applies alongside, not instead of, the clinical pathway. Don't let good nutrition become a reason to postpone the next step.

What mistakes do couples typically make at this stage?

After sitting with hundreds of couples at this exact point in their journey, four patterns come up again and again — and if you recognise yourselves in any of them, you're in very good company:

1. The man doesn't supplement. Both gametes contribute to embryo quality, and male-factor oxidative stress can impair outcomes even when standard semen analysis looks perfectly normal.
2. Couples switch products every few weeks, never giving any protocol the 90 days it needs to show an effect. We understand the temptation — when you're desperate for something to work, trying the next new thing feels proactive. But biologically, it's counterproductive.
3. Doses fall below therapeutic thresholds. A multivitamin containing 50 mg CoQ10 is not delivering the dose that's been studied in fertility trials. The numbers matter.
4. Couples stop supplements without discussing it with their fertility clinic, often because they were told to “bring a list” and interpreted this as “stop everything.” That's almost never what the clinic means.

Avoiding these pitfalls is straightforward for you: both partners start together, stay on a single protocol for three months, choose products that disclose therapeutic doses, and bring a written list to every clinic appointment rather than guessing what you're allowed.

Frequently asked questions

How long should we take fertility supplements before IUI?

The minimum useful window is three months, because eggs develop over ~85–90 days and sperm over ~72–74 days. Most fertility clinicians recommend beginning targeted supplementation 3 to 6 months before the first planned IUI cycle. Supplements started in the same month as the cycle influence the cycle after next, not the current one.

Can I take fertility supplements during IVF stimulation?

Most are safe to continue. Folate, vitamin D, CoQ10 at standard doses, zinc, and selenium are routinely continued. High-dose vitamin E (above 400 IU/day) and high-dose fish oil may be paused 7–10 days before egg retrieval at some clinics because of theoretical bleeding-time effects. Bring a written list of everything you take to your first clinic appointment.

Is CoQ10 safe for both partners?

Yes. CoQ10 at 100–600 mg/day has been used in female and male fertility trials over 60- to 90-day periods with a consistent safety record. It's not hormonal and doesn't interact with standard fertility medications. Ubiquinol is the active form and may be preferred in adults over 40 due to slightly better absorption, although the evidence base in fertility trials predominantly used ubiquinone. If you are taking warfarin or another anticoagulant, discuss it with your clinician.

Do I need to stop fertility supplements if I get pregnant?

You should transition from a fertility-specific supplement to a pregnancy-appropriate prenatal vitamin as soon as a positive test is confirmed. Core nutrients — folate, vitamin D, iodine, choline — continue throughout pregnancy. High-dose fertility-specific compounds (L-carnitine, myo-inositol beyond PCOS management) are typically stopped once pregnancy is established.

Can antioxidant supplements replace IVF?

No. Nutrition supports gamete quality but can't bypass a blocked tube, resolve a severe sperm count, or restart a non-ovulatory cycle. For couples with identifiable causes, supplementation complements treatment but doesn't replace it. The evidence that supports supplements as helpful is meta-analytic evidence on live birth rates alongside standard care, not in place of it.

What if only one partner will take supplements?

It is better than nothing, but the couple evidence is stronger than the single-partner evidence. Meta-analyses note that the largest effect sizes for couple outcomes were in trials where both partners were supplementing.¹² Where possible, supplement together.

How much does an advanced fertility nutrition protocol cost per month?

A well-designed dual-partner protocol from a single reputable supplier typically costs £40–£70 per month per person. Assembling the same dose profile from multiple single-ingredient products often costs more and reduces adherence.

Supporting Your Fertility with FertilitySmart

A well-designed protocol built around the evidence above is what “advanced fertility nutrition” should mean for you in practice — therapeutic doses, bioavailable forms, mechanism coverage for both of you as a couple, and honest evidence-based formulation.

If you're at the 12-month mark and looking for a single starting point for both partners, explore our advanced fertility nutrition range for women and men, formulated with the nutrients discussed in this guide. You can also explore FertilitySmart’s fertility supplements for men if you want to understand the specific formulation used in male-factor support.

For a wider orientation to the category, see the complete guide to fertility supplements for women and men, which sets out the full framework to help you choose supplements across your conception journey. To go deeper on how the “advanced” framework is built around the evidence above, see what makes a fertility supplement advanced.

Related Reading

• What Makes a Fertility Supplement Advanced? — the four-criteria framework for evaluating any fertility formulation against the evidence base used in this article.
• What Does CoQ10 Do for Fertility? — a deeper explanation of why CoQ10 is central to both the female and male protocols above.
• How to Improve Egg Quality Naturally — the lifestyle and nutrition inputs that shape the 90-day follicular development window.
• Sperm DNA Fragmentation: What to Know — the test that often prompts an advanced male protocol at this stage.
• Vitamins to Help Get Pregnant — the foundational nutrient layer that sits beneath any advanced protocol.
• Myo-inositol for Fertility and PCOS — when to add myo-inositol to the woman’s protocol.
• L-carnitine for Fertility — the evidence for L-carnitine in male-factor support.
• Explore our advanced fertility nutrition range — the product category that brings the framework above into a single formulation for both partners.

References

1. National Institute for Health and Care Excellence. Fertility problems: assessment and treatment. NICE guideline NG257. London: NICE; published 31 March 2026 (replaces CG156). https://www.nice.org.uk/guidance/ng257
2. Romualdi D, Ata B, Bhattacharya S, et al; ESHRE Guideline Group on Unexplained Infertility. Evidence-based guideline: unexplained infertility. Hum Reprod. 2023;38(10):1881-1890. doi:10.1093/humrep/dead150
3. Gougeon A. Human ovarian follicular development: from activation of resting follicles to preovulatory maturation. Ann Endocrinol (Paris). 2010;71(3):132-143. doi:10.1016/j.ando.2010.02.021
4. Amann RP. The cycle of the seminiferous epithelium in humans: a need to revisit? J Androl. 2008;29(5):469-487. doi:10.2164/jandrol.107.004655
5. Showell MG, Mackenzie-Proctor R, Jordan V, Hart RJ. Antioxidants for female subfertility. Cochrane Database Syst Rev. 2020;8(8):CD007807. doi:10.1002/14651858.CD007807.pub4. (Editorial note dated 5 March 2026 flagging 9 of 63 included trials — 7 retractions, 2 expressions of concern; editors confirm pooled findings are not meaningfully impacted.)
6. Lin G, Li X, Yie SLJ, 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;56(1):2389469. doi:10.1080/07853890.2024.2389469
7. Unfer V, Facchinetti F, Orrù B, Giordani B, Nestler J. Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials. Endocr Connect. 2017;6(8):647-658. doi:10.1530/EC-17-0243 (Authors include researchers affiliated with inositol manufacturers; readers should weigh this COI; corroborated for metabolic markers by independent reviews including the 2023/2024 update of the International Evidence-based PCOS Guideline.)
8. Frosst P, Blom HJ, Milos R, et al. A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase. Nat Genet. 1995;10(1):111-113. doi:10.1038/ng0595-111
9. Chu J, Gallos I, Tobias A, Tan B, Eapen A, Coomarasamy A. Vitamin D and assisted reproductive treatment outcome: a systematic review and meta-analysis. Hum Reprod. 2018;33(1):65-80. doi:10.1093/humrep/dex326
10. Stanhiser J, Jukic AMZ, McConnaughey DR, Steiner AZ. Omega-3 fatty acid supplementation and fecundability. Hum Reprod. 2022;37(5):1037-1046. doi:10.1093/humrep/deac027
11. Agarwal A, Baskaran S, Parekh N, et al. Male infertility. Lancet. 2021;397(10271):319-333. doi:10.1016/S0140-6736(20)32667-2
12. de Ligny W, Smits RM, Mackenzie-Proctor R, Jordan V, Fleischer K, de Bruin JP, Showell MG. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022;5(5):CD007411. doi:10.1002/14651858.CD007411.pub5
13. Wei G, Zhou Z, Cui Y, et al. A meta-analysis of the efficacy of L-carnitine/L-acetyl-carnitine or N-acetyl-cysteine in men with idiopathic asthenozoospermia. Am J Mens Health. 2021;15(2):15579883211011371. doi:10.1177/15579883211011371
14. Salvio G, Cutini M, Ciarloni A, Giovannini L, Perrone M, Balercia G. Coenzyme Q10 and male infertility: a systematic review. Antioxidants (Basel). 2021;10(6):874. doi:10.3390/antiox10060874

Marina Carter

Fertility Health Writer at FertilitySmart

Marina Carter is a specialist health writer with nearly a decade of experience in reproductive health, fertility nutrition, and evidence-based conception support. She has authored over 30 in-depth articles for FertilitySmart, translating peer-reviewed research into clear, practical guidance to support you and your partner on your fertility journey. Read full bio →