This is education, not medical advice, and nothing here is a diagnosis or a promise about your fertility. Nutrients are the one driver where "more" can be its own problem — so treat every marker below as a conversation with your provider, not a shopping list.
Nutrient status is the raw material your body draws on to build a mature egg, ovulate cleanly and prepare a lining for implantation. "Normal" nutrition labs can under-read it, because a standard panel checks whether you're deficient, not whether you're at the level associated with the best chance of conceiving — and because your body drains its stores before a routine test shows it. The nutrients most often under-read for fertility are iron (ferritin, not just hemoglobin), vitamin D, folate and B12, and omega-3 fats.
This is the most commonly missed of the four drivers, and the most quietly fixable. "Everything looks fine" is often literally true on the panel that was run — while the fertility-relevant marker was never measured, or was read against the wrong threshold. Here are the ones worth interpreting, and the honest state of the evidence for each.
Iron: the tank that empties before anemia shows
You can be iron-deficient without being anemic. Your body drains its iron stores first and only later shows it in a hemoglobin or anemia test. Ferritin measures those stores — and it can sit low while a standard "iron" check still reads normal. That's why ferritin, not hemoglobin, is the fertility-relevant number.
Low ferritin has been associated with anovulation and unexplained infertility. And in the large Nurses' Health Study II, women who used iron supplements had a meaningfully lower risk of ovulatory infertility than non-users (relative risk about 0.60). A frequently-cited target for trying to conceive is ferritin in the 40–70+ µg/L range — well above the bottom of most lab flags (often ~10–15).
The exact "optimal" ferritin figure for conception isn't a settled guideline number, and iron is the one nutrient you should never megadose blindly — too much is its own problem, and high iron carries its own risks. The evidence-aligned move is simple: ask for a ferritin test (not just hemoglobin), and if it's genuinely low, correct it with your provider rather than guessing.
Vitamin D: strong in one setting, mixed in another
Vitamin D acts more like a hormone than a vitamin, with receptors throughout reproductive tissue — so it belongs here. But the evidence has a clear split. In assisted reproduction, meta-analysis has found women who were vitamin-D-replete were more likely to have a live birth than those who were deficient. For natural conception in healthy women, the evidence is genuinely mixed — several studies find no significant difference.
Correcting a true vitamin D deficiency is low-risk and worthwhile for your overall health, and the fertility signal is at least suggestive. But we won't tell you that topping up vitamin D will get you pregnant, because the natural-conception evidence doesn't support that claim. Test it, correct a real deficiency, and don't hang your hopes on it.
Folate and B12: past the neural-tube minimum
Nearly everyone knows folate for preventing neural-tube defects. Fewer know it's also associated with conceiving in the first place. In preconception cohorts, women with the lowest dietary folate intake and no supplement had the lowest fecundability, while intake at or above the recommended ~400 µg/day fared better. In women undergoing fertility treatment, higher supplemental folic acid (above ~800 µg/day) and higher B12 intake have each been associated with a higher probability of live birth — and B12 works alongside folate, so they're best read as a pair.
Much of the strongest "live birth" data comes from assisted-reproduction populations, and folate/B12 are correlated with an overall nutrient-rich diet, which muddies cause. The practical, low-risk read: a preconception prenatal with folate (many women prefer a methylated form) is standard and sensible — but this is about correcting a gap and supporting the baseline, not megadosing your way to a result.
Omega-3: promising, not proven
Omega-3 fats are the raw material for the membranes and signaling molecules reproductive cells rely on, so the biological rationale is real. The human data is encouraging but not settled: in one cohort of women trying to conceive, those taking an omega-3 supplement had roughly 50% higher odds of conceiving in a given cycle (fecundability ratio ~1.51) than non-users, and a large North American study found higher omega-3 intake linked to higher fecundability.
The signal isn't universal — a parallel Danish cohort found no association, and a study measuring omega fatty acids in the blood found no difference between women who conceived quickly and those who didn't. So omega-3 sits in the "reasonable, low-risk, and possibly helpful" column, not the "proven" one. Worth including in the picture; not worth overselling.
CoQ10 and egg quality: the mitochondrial angle
Egg quality is, at a cellular level, largely an energy story — the maturing egg runs on its mitochondria, and that machinery becomes less efficient with age. CoQ10 (ubiquinol) sits at the centre of mitochondrial energy production and doubles as an antioxidant, which is why it has become one of the most-discussed fertility supplements. In a randomized trial of younger women with diminished ovarian reserve going through IVF, CoQ10 pre-treatment improved ovarian response and produced more high-quality embryos.
Two caveats. First, that trial — and most of the CoQ10 evidence — is in assisted reproduction, and in women with reduced ovarian reserve or older eggs, not the general population conceiving naturally. Second, even there, clinical-pregnancy and live-birth rates trended better but did not reach statistical significance. CoQ10 is low-risk and biologically reasonable, especially with age or low reserve — but it sits in the "supported, not proven" column, and it's worth discussing with your provider rather than assuming.
The trace minerals that quietly run your thyroid
This is where Nutrient Status stops being its own island and starts explaining another driver entirely. Two trace minerals do outsized work for hormone signaling. Iron is a structural component of thyroid peroxidase — the enzyme that builds thyroid hormone — so low iron can lower thyroid output and slow the conversion of storage hormone (T4) into its active form (T3). Selenium runs that same T4-to-T3 conversion, and low selenium is associated with markers of thyroid autoimmunity. Iodine is the raw material the thyroid uses in the first place.
The point isn't to add three more supplements. It's that a "normal" nutrient panel and an "off" thyroid can be the same story, read from two ends. That is what interpreting across systems means in practice — and why no single number, in any one driver, is the whole answer.
So what should I actually do with all this?
Not empty the supplement aisle. The move is to measure the right things and then interpret them. You might ask your provider some version of:
"Can we check ferritin — not just hemoglobin — plus vitamin D and B12/folate, and read them against fertility-relevant targets rather than only the deficiency flag? Where something's genuinely low, let's correct it properly; where it's fine, let's not chase it."
That's the whole discipline of this driver: replace guessing and blind supplementing with a measured, interpreted picture of what your body actually has to work with — corrected where it's short, left alone where it isn't. None of this guarantees anything, and none of it replaces your clinician. But it turns "everything looks fine" into something you can actually act on.