Omega-3 Fatty Acids and Fertility: A Complete Guide

Omega-3 fatty acids are long-chain polyunsaturated fats — chiefly EPA and DHA from oily fish, and ALA from plants — that the body uses to build cell membranes and regulate inflammation. In reproductive biology, omega-3s shape the membranes of egg cells and sperm, influence the hormonal signalling environment around ovulation, and have been linked in multiple cohort studies and meta-analyses to improved chances of conception.

If you're trying to conceive, omega-3 is one of the better-evidenced nutrients you can pay attention to — and one of the most commonly under-consumed in the UK diet. This guide walks through what the science actually shows, how much DHA and EPA you need, where to get them, and what to watch for if you're pregnant or planning to be.

What are omega-3 fatty acids, and why do they matter for fertility?

Omega-3s are a family of polyunsaturated fatty acids your body cannot make in meaningful amounts and must obtain from food or supplements. The three forms that matter most are alpha-linolenic acid (ALA, from plants such as flaxseed and walnuts), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) — both EPA and DHA come primarily from oily fish and algae.

In the reproductive system, EPA and DHA serve two distinct functions. DHA is built directly into the phospholipid bilayer of egg-cell and sperm-cell membranes, where it shapes membrane fluidity — a property that influences how an egg responds to fertilisation signals and how a sperm cell swims, binds, and penetrates.^3,4 EPA, by contrast, is a precursor to the resolvins and series-3 prostaglandins that broadly down-regulate inflammation.⁹ The same anti-inflammatory pathway is thought to influence the inflammatory tone of reproductive tissues — your uterus and ovaries included — though human evidence specific to those tissues is still catching up with the broader inflammation work.

Citable fact: DHA is the most abundant polyunsaturated fatty acid in mammalian sperm membranes and a major phospholipid component of oocyte membranes, which is why it sits at the centre of the nutritional case for omega-3 in fertility.⁴

The Western and modern UK diet has shifted heavily toward omega-6 fats (vegetable oils, processed foods) and away from oily fish, leaving most adults well below intake targets. The UK National Diet and Nutrition Survey shows the average adult eats well below the recommended oily fish intake — around 56 g per week against the 140 g recommended portion.¹⁷ If your week looks anything like that, you're in the typical UK pattern — and it's one of the more straightforward gaps to close in preconception nutrition.

Does omega-3 supplementation improve the chances of conception?

The strongest single piece of evidence in women trying to conceive naturally comes from the Time to Conceive (TTC) cohort published in Human Reproduction in 2022. Among 900 women aged 30–44 attempting pregnancy, those who reported taking an omega-3-containing supplement had a fecundability ratio of 1.51 (95% CI 1.12–2.04) compared with non-users — roughly 50% higher odds of conceiving in any given cycle.¹

A 2024 meta-analysis in Heliyon pooled six trials in women undergoing fertility treatment (n=1,789), four trials in women conceiving naturally (n=2,607), and three trials measuring fertilisation rate (n=1,725 oocytes). Aggregated odds ratios were 1.74 for pregnancy in ART, 1.36 for natural conception, and 2.14 for fertilisation rate — all favouring omega-3.² The authors flagged high heterogeneity (I²>68%) across studies, so the precise effect size is uncertain, but the direction of effect was consistent.

It's worth being honest about what this evidence does and doesn't show. These are mostly observational and small-trial findings; we don't yet have a large, definitive randomised trial of omega-3 supplementation versus placebo for pregnancy in unselected women trying to conceive. What you do have is a consistent signal across multiple study designs, biological plausibility through membrane and prostaglandin pathways, and an excellent safety profile — enough to put omega-3 on your preconception shortlist without overstating what it can do on its own.

How does omega-3 support egg quality?

Egg quality refers to the chromosomal integrity and developmental competence of the oocyte — both of which decline gradually with age. Omega-3s appear to support egg quality through two main routes: membrane composition and oxidative environment.

DHA incorporated into the oocyte's phospholipid membrane preserves the fluidity and signalling capacity needed for meiotic maturation and successful fertilisation.³ A 2022 systematic review in the European Journal of Obstetrics & Gynecology and Reproductive Biology identified five studies — three small RCTs and two observational studies — examining dietary omega-3 intake and embryo or oocyte outcomes in ART cycles. All five reported that higher omega-3 intake was associated with improved embryo morphology, morphokinetics, or oocyte-quality markers, though the authors did not pool the data into a meta-analysis because of methodological heterogeneity.¹⁰ The evidence base is small and mostly embryo-focused, but it points consistently in one direction.

Animal evidence also supports the egg-quality angle: a 2012 mouse study published in Aging Cell found that a long-term diet rich in omega-3 PUFAs prolonged the reproductive lifespan and improved oocyte quality in ageing mice.¹¹ Mouse evidence doesn't directly translate to humans, but it strengthens the biological plausibility — and it points to a mechanism that is plausibly modifiable in women in their 30s and 40s, the group most concerned about age-related egg-quality decline. If that's the territory you're in, omega-3 is one of a small handful of evidence-supported levers you can pull through nutrition.

If you're working on egg quality more broadly, omega-3 sits alongside CoQ10, vitamin E, and good general nutrition — see How to Improve Egg Quality Naturally for the full picture.

How do omega-3s affect sperm quality and male fertility?

Sperm membranes are unusually rich in DHA — about 25–35% of total sperm phospholipid fatty acids — and DHA content correlates with motility, morphology, and fertilising capacity.⁴

A 2018 systematic review and meta-analysis in Advances in Nutrition examined nutrients and supplements affecting sperm quality across randomised trials. Omega-3 fatty acid supplementation produced statistically significant improvements in sperm concentration (weighted mean difference 10.98 × 10⁶/mL; 95% CI 10.25–11.72) and sperm total motility (weighted mean difference 7.55%; 95% CI 7.09–8.01) versus controls.⁵

An earlier PRISMA-format systematic review in Andrology (2019) included 16 clinical or observational trials of DHA or DHA+EPA intake in men. Fourteen of the 16 reported improvement in at least one sperm marker associated with omega-3, and the effect appeared more pronounced in men with idiopathic infertility than in young healthy controls.⁶ A 2023 network meta-analysis of non-pharmaceutical interventions for sperm quality found a statistically significant improvement in forward motility with omega-3 supplementation (mean difference +3.50, 95% CI 2.21–4.79) and placed omega-3 among the most effective interventions for sperm concentration.¹² If you or your partner are working on the male side of the picture, the evidence base behind omega-3 is at least as strong as it is for the female side.

A practical note: sperm production takes around 64 days (a full spermatogenic cycle), so if you or your partner are starting a fertility-focused omega-3 routine, expect at least 8–10 weeks before any change shows up in a semen analysis. We cover this timing point in more depth in our guide to improving sperm motility naturally.

Does omega-3 improve IVF outcomes?

For couples in assisted reproduction, the evidence is suggestive but not definitive. The Abodi 2022 systematic review found that all five included ART studies reported a favourable association between omega-3 intake and embryo morphology, morphokinetic parameters, or pregnancy outcomes.¹⁰ The 2024 Heliyon meta-analysis quantified this: pregnancy odds in women undergoing fertility treatment were 74% higher (OR 1.74) with omega-3 versus controls.²

An earlier Dutch cohort study (2011, Fertility and Sterility) examined preconception dietary intake in 235 women undergoing IVF/ICSI and found that higher omega-3 intake — especially ALA and DHA — was associated with improved embryo morphology.¹³ That was a dietary study, not a supplementation trial, so it reflects real-world food intake rather than capsules — but it points in the same direction.

Where omega-3 sits within your IVF supplementation protocol is a more nuanced question, because clinics differ on what they recommend stopping and continuing around egg collection and transfer. Always coordinate any supplementation with your fertility clinic before and during an IVF cycle — especially anything with anti-platelet effects in higher doses.

How much DHA and EPA do you need for fertility?

For general adult health, the UK's Scientific Advisory Committee on Nutrition (SACN) and the British Dietetic Association point to at least one portion of oily fish per week, which delivers approximately 250 mg combined EPA+DHA per day on average.⁷ For preconception and pregnancy, the International Society for the Study of Fatty Acids and Lipids (ISSFAL) consensus advises an additional 200 mg DHA daily on top of general adult intake.⁸ Combined, that works out to roughly 250–500 mg EPA+DHA per day in the preconception window, with at least 200 mg of that as DHA.

In studies showing a fertility benefit, women were typically taking supplements containing 1,000 mg or more of combined EPA+DHA per day — toward the upper end of what's commonly used.² A reasonable target for you in the preconception window is therefore 500–1,000 mg combined EPA+DHA daily, with at least 200 mg of that as DHA, from your diet plus supplementation as needed.

How DHA and EPA compare for fertility

What's the best source of omega-3 — oily fish, fish oil, or algae?

Whole oily fish remains the gold-standard source: a single portion of salmon, mackerel, sardines, herring or trout delivers roughly 1,500–3,500 mg combined EPA+DHA, alongside vitamin D, selenium, iodine, and protein.⁷ The NHS recommends two portions of fish a week, including one oily portion, for general health.

If you don't eat fish often, a high-quality fish oil supplement (standardised to a stated EPA and DHA content per capsule, not just "fish oil 1,000 mg") is the most evidence-aligned alternative. Look for third-party tested products (IFOS, GOED) to confirm freshness and absence of heavy metals and PCBs.

For vegans and vegetarians — or anyone wary of fish — algae-derived DHA (and increasingly DHA+EPA) provides the same long-chain fatty acids found in fish oil, sourced from the microalgae fish themselves eat to acquire DHA. Algae oil is mercury-free by virtue of sitting at the bottom of the food chain, which makes it a reasonable choice during the preconception and pregnancy window. Plant ALA from flaxseed and walnuts contributes useful background omega-3, but your body converts ALA to DHA very inefficiently — typically well under 1%, and often closer to 0.05–0.1% in adult men — so plant sources cannot replace a DHA-providing source for fertility purposes.¹⁴

A few fish to avoid in the trying-to-conceive and pregnancy windows because of mercury content: shark, swordfish, marlin (avoid altogether in pregnancy and pre-conception per UK NHS guidance), and tuna (limit to two tuna steaks or four medium tins per week).¹⁵ Cod liver oil should also be avoided in pregnancy because it contains high doses of preformed vitamin A (retinol), which is teratogenic at high levels.⁷

Are there risks or side effects to consider?

Omega-3 has an excellent safety profile at the doses used for fertility. The most common side effects are minor — fishy aftertaste, mild reflux, soft stools — and are usually reduced by taking capsules with food or freezing them.

A few caveats worth knowing:

• Anticoagulants: The European Food Safety Authority concluded that combined EPA+DHA intakes up to around 5,000 mg/day do not raise safety concerns for adults and do not appear to increase the risk of spontaneous bleeding.¹⁶ Some clinicians still recommend caution at higher doses if you're on blood thinners (warfarin, aspirin, or direct oral anticoagulants), because of theoretical effects on platelet aggregation. A pragmatic approach: if you take blood thinners, check with your GP before exceeding around 1,000 mg/day, and avoid combining high-dose fish oil with other supplements known to affect bleeding (such as high-dose vitamin E).
• Fish allergy: People allergic to fish should choose algae-derived DHA rather than fish oil.
• Cod liver oil in pregnancy: As above, avoid because of preformed vitamin A.
• Mercury: Reputable fish oil and algae oil supplements are mercury-screened. Whole-fish intake should follow the UK NHS guidance on which fish to limit or avoid.
• IVF cycles: Some clinics ask patients to pause anything with anticoagulant or anti-platelet effect (including high-dose fish oil) in the days around egg retrieval. Always confirm with your clinic.

How long does it take omega-3 to support fertility?

This is one of the most common practical questions, and the honest answer comes from reproductive biology rather than supplement marketing. Oocytes complete their final maturation over roughly 90 days, and a full cycle of spermatogenesis takes about 64 days. That means any nutritional change you make — including starting omega-3 — primarily affects the eggs and sperm that will be ready for fertilisation 2–3 months from now.

In practice, allow at least three months of consistent intake before you judge the effect on egg quality or semen parameters. If you're preparing to conceive, starting your preconception nutrition (omega-3, folic acid, and a balanced fertility diet) three to six months before active trying lines up with both gamete maturation and the gradual restoration of your tissue omega-3 status.

Frequently Asked Questions

Can omega-3 alone help me get pregnant?

No single nutrient is a fertility solution on its own. Omega-3 is one part of your wider preconception picture, which includes folate, vitamin D, a healthy weight, regular sleep, moderate exercise, and managing any underlying conditions such as PCOS or thyroid issues. The evidence suggests omega-3 contributes meaningfully to that picture rather than carrying it alone.

Is fish oil safe in pregnancy?

Yes — a standardised fish oil supplement (not cod liver oil) at recommended doses is considered safe in pregnancy, and some clinicians actively encourage it for your baby's brain development. Avoid cod liver oil in pregnancy because of its high preformed vitamin A content.

Does omega-3 help with PCOS-related fertility issues?

Possibly. Several small trials in women with PCOS have shown omega-3 supplementation may improve menstrual regularity and reduce androgen levels, though the evidence is mixed. If you have PCOS, omega-3 is one option to consider as part of your wider PCOS fertility plan — see our guide to PCOS and fertility for the full picture.

What's the difference between fish oil and krill oil for fertility?

Both deliver EPA and DHA. Krill oil contains the omega-3s primarily in phospholipid form, which some small studies suggest is absorbed slightly more efficiently — but per milligram of EPA+DHA, it tends to be considerably more expensive. For most people, a standardised fish oil or algae oil is the more practical choice for your budget and your daily routine.

Can I get enough omega-3 from flaxseed instead of fish?

Probably not for fertility purposes. Flaxseed provides ALA, the plant-form omega-3, which the body converts to DHA at very low efficiency — typically well under 1% in adults, and as low as 0.05% in men. Flaxseed is still a useful addition to the diet, but if you're vegan or don't eat fish, algae-derived DHA is the more reliable route to fertility-relevant omega-3 status.

Should my partner take omega-3 too?

If you're trying as a couple, yes — the male-fertility evidence for omega-3 (improved sperm concentration and motility) is at least as strong as the female evidence. A shared supplement habit also makes it easier to stay consistent over the preconception window.

How quickly does omega-3 build up in the body?

Your red blood cell omega-3 levels — a reasonable proxy for tissue status — typically rise meaningfully within 4–6 weeks of consistent supplementation and plateau by around 3 months. For fertility outcomes tied to gamete development, the more relevant timeline for you is the 2–3 month maturation window of eggs and sperm.

Supporting Your Fertility with FertilitySmart

A balanced preconception diet rich in oily fish, alongside folate, antioxidants, and key minerals, is the foundation for omega-3-supported fertility. Supplementation can help close the gap if you don't eat much fish or you want to be sure of a consistent daily intake.

At FertilitySmart, we offer both fertility supplements for women and fertility supplements for men formulated with the nutrients discussed in this guide as part of a broader preconception blend. Explore our range of evidence-based fertility supplements alongside an oily-fish-inclusive diet or an algae DHA alternative.

Related Reading

• How to Improve Egg Quality Naturally
  The pillar guide that places omega-3 alongside CoQ10, vitamin E, and lifestyle factors for women working on egg quality.
• What Does CoQ10 Do For Fertility?
  Companion nutrient that supports the same mitochondrial environment in maturing oocytes.
• Vitamin E for Fertility
  Antioxidant evidence and dosing alongside omega-3.
• AMH Levels and Fertility
  How to interpret AMH testing in the context of egg quality work.
• Fertility Diet
  The broader nutritional pattern that includes oily fish as a regular feature.
• How to Improve Sperm Motility Naturally
  Male-side companion piece with practical omega-3 application.
• Sperm DNA Fragmentation
  The oxidative damage marker most relevant to the male omega-3 evidence.
• Complete Guide to Fertility Supplements
  The full preconception supplement landscape with omega-3 in context.
• Top 10 Fertility Supplements
  Ranking and rationale, including omega-3's place in the top tier.

This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting or changing any supplement regimen — particularly if you are pregnant, trying to conceive, taking medication, or have an underlying health condition.

References

1. Stanhiser J, Jukic AMZ, McConnaughey DR, Steiner AZ. Omega-3 fatty acid supplementation and fecundability. Human Reproduction. 2022;37(5):1037–1046. doi.org/10.1093/humrep/deac027
2. Trop-Steinberg S, Gal M, Azar Y, Kilav-Levin R, Heifetz EM. Effect of omega-3 supplements or diets on fertility in women: A meta-analysis. Heliyon. 2024;10(8):e29324. doi.org/10.1016/j.heliyon.2024.e29324
3. Wonnacott KE, Kwong WY, Hughes J, et al. Dietary omega-3 and -6 polyunsaturated fatty acids affect the composition and development of sheep granulosa cells, oocytes and embryos. Reproduction. 2010;139(1):57–69. doi.org/10.1530/REP-09-0219
4. Esmaeili V, Shahverdi AH, Moghadasian MH, Alizadeh AR. Dietary fatty acids affect semen quality: a review. Andrology. 2015;3(3):450–461. doi.org/10.1111/andr.12024
5. Salas-Huetos A, Rosique-Esteban N, Becerra-Tomás N, Vizmanos B, Bulló M, Salas-Salvadó J. The effect of nutrients and dietary supplements on sperm quality parameters: a systematic review and meta-analysis of randomized clinical trials. Advances in Nutrition. 2018;9(6):833–848. doi.org/10.1093/advances/nmy057
6. Falsig AL, Gleerup CS, Knudsen UB. The influence of omega-3 fatty acids on semen quality markers: a systematic PRISMA review. Andrology. 2019;7(6):794–803. doi.org/10.1111/andr.12649
7. NHS. Fish and shellfish. NHS.uk. Updated 2023. nhs.uk/live-well/eat-well/food-types/fish-and-shellfish-nutrition
8. Koletzko B, Cetin I, Brenna JT; Perinatal Lipid Intake Working Group. Dietary fat intakes for pregnant and lactating women. British Journal of Nutrition. 2007;98(5):873–877. doi.org/10.1017/S0007114507764747
9. Calder PC. Omega-3 fatty acids and inflammatory processes: from molecules to man. Biochemical Society Transactions. 2017;45(5):1105–1115. doi.org/10.1042/BST20160474
10. Abodi M, De Cosmi V, Parazzini F, Agostoni C. Omega-3 fatty acids dietary intake for oocyte quality in women undergoing assisted reproductive techniques: A systematic review. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2022;275:97–105. doi.org/10.1016/j.ejogrb.2022.06.019
11. Nehra D, Le HD, Fallon EM, et al. Prolonging the female reproductive lifespan and improving egg quality with dietary omega-3 fatty acids. Aging Cell. 2012;11(6):1046–1054. doi.org/10.1111/acel.12006
12. Chen Z, Hong Z, Wang S, Qiu J, Wang Q, Zeng Y, Weng H. Effectiveness of non-pharmaceutical intervention on sperm quality: a systematic review and network meta-analysis. Aging (Albany NY). 2023;15(10):4253–4268. doi.org/10.18632/aging.204727
13. Hammiche F, Vujkovic M, Wijburg W, et al. Increased preconception omega-3 polyunsaturated fatty acid intake improves embryo morphology. Fertility and Sterility. 2011;95(5):1820–1823. doi.org/10.1016/j.fertnstert.2010.11.021
14. Burdge GC, Calder PC. Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reproduction Nutrition Development. 2005;45(5):581–597. doi.org/10.1051/rnd:2005047
15. NHS. Foods to avoid in pregnancy. NHS.uk. Updated 2023. nhs.uk/pregnancy/keeping-well/foods-to-avoid
16. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the Tolerable Upper Intake Level of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). EFSA Journal. 2012;10(7):2815. doi.org/10.2903/j.efsa.2012.2815
17. Public Health England / Office for Health Improvement and Disparities. National Diet and Nutrition Survey: rolling programme. NDNS years 9 to 11 (2016/17 to 2018/19) and 2019 to 2023 reports. Updated 2024. gov.uk/government/collections/national-diet-and-nutrition-survey

Marina Carter

Health & Fertility Writer at FertilitySmart

Marina writes evidence-based fertility content, translating peer-reviewed research into practical, supportive guidance for individuals and couples trying to conceive. Read Full Bio →