Ferritin before pregnancy: why your iron stores matter
Ferritin is the measure of iron your body has in reserve, and in Australia a level below 30 micrograms per litre is considered iron deficiency, even though many lab reports print anything above about 15 as normal.
Pregnancy draws those reserves down harder than any other stage of life. That is why the number is worth knowing before you conceive rather than after, and it sits on the preconception checklist for exactly that reason.
What ferritin measures, and why it is not on a standard blood test
Ferritin is the protein that stores iron, and measuring it tells you how much iron you have banked rather than how much you are currently using. Among the iron tests available, it is the most sensitive and specific measure of your stores.¹
A full blood count does not include it. A full blood count measures haemoglobin, which is the iron already circulating and doing its job. Your body protects haemoglobin by drawing on the stores behind it, so haemoglobin is the last thing to fall.
That sequence is the reason so many women are told their iron is fine while their reserves are quietly emptying. By the time haemoglobin drops, the stores have usually been low for months.
Ferritin is a separate request on the pathology form. If you want the number, you have to ask for it by name, which is covered in our guide to preconception blood tests.
What your ferritin number means before pregnancy
Below 30 is low, the reference range on your report is not the same as the clinical threshold, and inflammation can push the number up.
What is a normal ferritin before pregnancy?
A ferritin below 30 micrograms per litre is diagnostic of iron deficiency, and the Royal College of Pathologists of Australasia uses that same threshold in its position statement on iron studies.¹˒²
The confusion comes from the lab report. Many Australian laboratories set their low flag at roughly 15, so a result of 22 can be printed inside the reference range while meeting the accepted clinical definition of deficiency. A reference range describes what is common in the population tested, not what is optimal for someone about to grow a baby.
This is not rare. In a cross-sectional survey of 736 young Australian women aged 18 to 39, 34.8% had a ferritin below 30, and low ferritin was more common in women reporting more than two days of heavy menstrual bleeding.³ Being observational, it tells you how common low stores are, not what causes them in any individual.
So if you were told your iron was fine, ask to know your ferritin number.
Why do iron stores matter more once you are pregnant?
Pregnancy raises your iron requirement by about 50%, from a recommended dietary intake of 18 milligrams a day to 27 milligrams a day.⁴
That extra iron goes to a larger blood volume, the placenta and your growing baby, and demand climbs steeply through the second and third trimesters. Diet alone rarely covers the gap, which is why iron studies are part of routine antenatal care in Australia.
Starting pregnancy with full reserves means you have something to draw on when demand peaks. Starting with a ferritin of 15 means the same demand curve begins from an empty account, and correcting iron while pregnant is slower than correcting it beforehand.
The 2025 Haematology in Obstetrics and Women's Health Collaborative consensus statement concludes that optimising iron before pregnancy is the way to avoid deficiency developing during it.⁵ Worth knowing: the authors graded much of their guidance on low certainty evidence, and several declared speaker fees from iron manufacturers, which is disclosed in the paper.⁵
Can ferritin look normal when your iron is low?
Yes. Ferritin is also an acute phase protein, meaning it rises with infection, inflammation and some chronic conditions, and it can be pushed high enough to mask genuinely low stores.¹
In practical terms, a ferritin measured while you are unwell, or during a flare of an inflammatory condition, can overestimate what you actually have in reserve. In the presence of inflammation, a ferritin as high as 300 can still be compatible with iron deficiency, which is why your GP interprets it alongside transferrin saturation and your red cell size rather than on its own.¹
If you had blood taken while sick and the result surprised you, the sensible move is to repeat it once you are well.¹ One reassuring point: for most healthy women with no inflammatory condition, ferritin does what it is supposed to do, and the number on the page is a fair reflection of your stores.
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How to raise a low ferritin before you conceive
Correcting low stores with tablets takes months, and how you take iron matters as much as which brand you buy.
How long does it take to raise ferritin?
Rebuilding iron stores with tablets takes months, not weeks, with a typical treatment course of three to six months.¹
That timeline is the practical argument for testing early. Correcting haemoglobin is relatively quick, but refilling the store behind it is the slow part, and stopping as soon as you feel better usually means the stores never fill.
Absorption is where most of the difference is made. Iron is best taken on an empty stomach, because phosphates, phytates and tannates in food bind it, and tea, coffee and calcium are meaningful blockers.¹ Vitamin C improves absorption, which is why some preparations combine the two.¹
If tablets are not tolerated, or your stores need refilling faster than oral iron allows, an iron infusion is an option to discuss with your GP.¹ That is a clinical decision rather than a default, and another reason to raise it early.
Should I take iron daily or every second day?
The evidence supports either, and the honest answer is that alternate-day dosing absorbs better per dose while producing similar results overall.
A large single dose of iron triggers a temporary rise in hepcidin, the hormone that dials down how much iron you absorb, and that block lasts into the next day. In two randomised trials in iron-depleted women, taking iron on alternate days rather than consecutive days raised the proportion absorbed from 16.3% to 21.8%.⁶ These were absorption studies using labelled iron, not trials measuring how people felt.
A 2025 systematic review of 11 randomised trials in 1,014 people then compared the two schedules on outcomes and found no meaningful difference in haemoglobin or ferritin, with alternate-day dosing better tolerated.⁷ The authors rated the certainty of evidence as very low.
So the schedule you can actually stick to for three months matters more than which one you choose.
What this means for you
Ask your GP for a ferritin test by name before you start trying, and ask for the number rather than whether it was normal.
If it comes back below 30, that is worth acting on, and it is worth asking your GP why it is low rather than only treating it, because heavy periods, coeliac disease and low dietary intake all need different follow-up.
You do not need to delay trying while you correct it. Iron can be replaced while you are trying to conceive and during pregnancy, and starting now simply means you are further along by the time demand rises.
Bring one question to the appointment: what is my ferritin, and if it is low, what is the plan and when will we recheck it?
References
- Baird-Gunning J, Bromley J. Correcting iron deficiency. Aust Prescr. 2016;39(6):193-9.
- Royal College of Pathologists of Australasia. Position statement: the use of iron studies, ferritin and other tests of iron status. Sydney: RCPA; 2020.
- Islam RM, Bell RJ, Skiba MA, et al. Iron insufficiency among young Australian women: a population-based survey. Intern Med J. 2020 Apr;50(4):420-426.
- National Health and Medical Research Council. Nutrient reference values for Australia and New Zealand: iron. Canberra: NHMRC; 2006.
- Clarke L, Froessler B, Tang C, et al. Iron optimisation in pregnancy: a Haematology in Obstetric and Women's Health Collaborative consensus statement. Intern Med J. 2025 Feb;55(2):300-307.
- Stoffel NU, Cercamondi CI, Brittenham G, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017;4(11):e524-e533.
- Dhanvijay AD, Patidar V, Singh J, et al. Efficacy of daily versus alternate day oral iron supplementation for management of anaemia among general population: a systematic review and meta-analysis. BMC Pharmacol Toxicol. 2025;26:152.
Written by Bella Katahanas · BBiomedSc, MEpi · Clinical epidemiologist
I read pregnancy research so you do not have to. More about me
Published: 3rd August 2026 · Last reviewed: 3rd August 2026
How I review research: Editorial policy
Educational only, not medical advice. Full disclaimer
This article is for educational purposes only and does not constitute medical advice. Research findings describe patterns across populations and may not apply to you. Always discuss your own situation with your GP, midwife or obstetrician.
