Anaemia in pregnancy is common, easily missed, and genuinely worth catching early, largely because everyone expects to feel tired when pregnant and so the symptoms get waved away.
But there is a difference between ordinary pregnancy tiredness and the particular flatness of low iron. If you are breathless climbing stairs you used to manage easily, or your heart races when you stand, that is worth looking at properly rather than accepting as part of the deal.
Here is what is happening, what gets tested and when, and what genuinely helps.
Why iron demand rises so steeply in pregnancy
Your blood volume increases by roughly forty to fifty per cent during pregnancy. That is an enormous physiological undertaking, and every additional red blood cell needs iron to build.
At the same time, your baby is drawing iron from you to build their own supply. In the third trimester particularly, they lay down stores intended to last them through their first six months of life, since milk is relatively low in iron. Your body prioritises this transfer, which is generous of it and costly for you.
Add that many women enter pregnancy with modest stores already, often after years of menstruation without much attention to iron, and the arithmetic becomes clear. Requirements roughly double across pregnancy, and dietary intake rarely doubles alongside.
There is one genuine complication in interpreting all this. Your plasma volume increases faster than your red cell mass, which dilutes your blood. This is called physiological anaemia of pregnancy, and it means a modest drop in haemoglobin is entirely normal and expected rather than a problem. It is why pregnancy has its own reference ranges, and why a result that would concern a clinician outside pregnancy may be perfectly fine within it.
Anaemia in pregnancy: the symptoms worth noticing
Tiredness is the obvious one and the least useful, because everyone assumes it is just being pregnant. These are the symptoms that genuinely differentiate.
- Breathlessness on stairs or during ordinary activity that never affected you before
- Heart palpitations or a racing heart, particularly on standing
- Dizziness or lightheadedness, especially standing up quickly
- Persistent brain fog beyond ordinary pregnancy forgetfulness
- Feeling cold when others around you are comfortable
- Restless legs at night, which has a strong association with low iron
- Pale skin, most noticeable inside your lower eyelids
- Headaches
- Unusual cravings, particularly for ice, which is called pica and is a recognised sign of iron deficiency
- Craving non-food items such as chalk, soil or paper, which should always be mentioned
Any one alone has other explanations. Several together, particularly breathlessness and palpitations, deserve a blood test rather than reassurance.
Craving ice is worth flagging specifically, because it is so distinctive and so frequently unmentioned. Women often assume it is a quirk rather than a symptom.
What gets tested and when
In the UK you will have your haemoglobin checked routinely at two points.
At your booking appointment, usually around eight to twelve weeks, as part of your initial bloods.
At around twenty-eight weeks, timed deliberately, since this is when demand climbs steeply and there is still time to treat before birth.
You may be tested more often if you have risk factors: a multiple pregnancy, pregnancies close together, a history of anaemia, heavy periods before conceiving, a vegetarian or vegan diet, or a condition affecting absorption such as coeliac disease.
If your haemoglobin comes back below the pregnancy threshold, your midwife will usually start you on iron and recheck in a few weeks.
Haemoglobin and ferritin are not the same thing
This is the most useful thing in this article, so please do read it properly.
Routine antenatal bloods measure haemoglobin, the oxygen-carrying protein in your red blood cells. If haemoglobin is low, you have anaemia.
But haemoglobin falls last. Your body runs down its stored iron first, protecting circulating haemoglobin for as long as it possibly can.
Ferritin measures those stores, and ferritin can be genuinely depleted while haemoglobin still reads normal. This is precisely why so many women are told their bloods are fine while feeling dreadful. The test that would have shown the problem was not the test that was run.
Ferritin is not routinely checked in every pregnancy in every trust. If you have symptoms, or risk factors, it is entirely reasonable to ask for it specifically, and to ask for the number rather than being told it is within range.
Reference ranges are wide and the bottom end is low. Many practitioners consider ferritin below around 30 to be genuinely depleted in pregnancy, even where haemoglobin looks acceptable, since your stores are what will carry you through birth and the postpartum weeks.
One caveat worth knowing: ferritin rises with inflammation or infection, so if you are unwell when tested, the result can look falsely reassuring.
Iron-rich foods that work in pregnancy
There are two kinds of dietary iron and the difference genuinely matters.
Haem iron, from animal sources, absorbed at roughly fifteen to thirty-five per cent. Red meat is the standout, alongside poultry, sardines and other oily fish. Do note that liver, while exceptionally iron-rich, should be avoided in pregnancy because of its very high vitamin A content.
Non-haem iron, from plants, absorbed at only around two to twenty per cent, so it needs help. Lentils, chickpeas and beans, dark leafy greens, pumpkin seeds, tofu, dried apricots, and fortified breakfast cereals.
Allowing for aversions, which is the real challenge. If meat is currently impossible, and it often is, fortified cereal with orange juice, lentils blended into a soup, or dried apricots as a snack all contribute without needing you to face anything difficult. Pumpkin seeds scattered over whatever you are already eating is genuinely one of the easiest wins available.
Do not aim for perfection here. Aim for something iron-containing, most days, paired well.
Helping your body absorb it
This is where you get the most benefit for the least effort.
Pair with vitamin C. This is the big one, and it substantially increases absorption of non-haem iron. Squeeze lemon over lentils. Add peppers to a bean stew. Have fruit with a fortified cereal. Tomatoes with almost anything.
Keep tea and coffee away from iron-rich meals. The tannins significantly inhibit absorption, and the effect is substantial. Leave an hour either side. Given how much tea most of us drink, this single change can make a real difference.
Space calcium apart. Calcium competes with iron for absorption, so a large glass of milk alongside an iron-rich meal works against you.
Cook in cast iron if you have a pan, which genuinely increases iron content, particularly with acidic foods like tomato-based dishes.
If digestion is sluggish, absorption may be affected too. Our article on gut health covers this, and pregnancy constipation is common enough that it is worth reading alongside.
Iron supplements in pregnancy
If your midwife prescribes iron, a few things worth knowing.
Please do not self-prescribe high-dose iron. Excess iron is genuinely harmful and accumulates, and dosing in pregnancy should be led by your midwife or GP based on your actual bloods. A standard pregnancy multivitamin containing a modest amount is a different matter, but therapeutic doses should follow a test.
Gentler forms exist. Ferrous sulphate is commonly prescribed and commonly causes constipation and nausea, neither of which you need on top of pregnancy. Ferrous bisglycinate, sometimes sold as gentle iron, is generally far better tolerated, as are liquid preparations. If what you have been given is making you miserable, please go back and ask rather than quietly stopping.
Alternate-day dosing may work better. This surprises people. Research suggests taking iron every other day can result in better absorption than daily dosing, because a hormone called hepcidin rises after a dose and blocks absorption for a day or so afterwards. It also tends to cause fewer side effects. Worth raising with your midwife.
Take it with vitamin C and away from tea, coffee, calcium and antacids.
Expect constipation and get ahead of it. Iron is a leading cause, and pregnancy constipation is already common thanks to progesterone slowing your gut. Fibre, plenty of fluids, and asking about a stool softener early rather than waiting until it is a problem.
Why this matters for birth and recovery
This is the part most worth understanding, because it reframes iron from a pregnancy issue into a recovery one.
You will lose blood at delivery. Average loss is around 300 to 500ml for a vaginal birth and roughly double that for a caesarean. If you go into that with depleted stores, you come out considerably worse off.
Low iron at birth is associated with greater fatigue in the postpartum weeks, and the exhaustion of low iron on top of newborn sleep deprivation is genuinely punishing. There are also associations with low mood postnatally, which matters given how much else is happening at that point.
Building your stores now is one of the more useful things you can do for the woman you will be in three months. Our article on postpartum anaemia covers what happens afterwards, and reading the two together gives you the full picture.
Our guide to preparing for birth is also worth a look, since going in well-nourished and well-rested affects how the whole thing feels.
If you are vegetarian or vegan
Entirely manageable, with more deliberate attention.
Your requirements are effectively higher, since plant iron is absorbed so much less efficiently. Some guidance suggests vegetarians and vegans may need up to nearly twice the iron intake to achieve the same absorption.
Practically: make vitamin C pairing a habit rather than an occasional thing, since it matters more for you. Lean on lentils, chickpeas, tofu, fortified cereals, pumpkin seeds and dried apricots. Soaking or sprouting pulses reduces the phytates that bind minerals, which helps absorption modestly.
Ask for ferritin testing specifically, and consider asking earlier than twenty-eight weeks, since you are in a higher-risk group.
Watch B12 alongside, which is essential in pregnancy, requires supplementation on a vegan diet, and causes anaemia and exhaustion that looks identical to iron deficiency.
When to speak to your midwife
Please raise it if you have exhaustion beyond what feels reasonable, or several of the symptoms above clustering together, particularly breathlessness and palpitations.
Please seek prompt advice for breathlessness at rest rather than on exertion, fainting or near-fainting, chest pain, or a racing heart that does not settle.
And do mention it if you are craving ice or non-food items, since both are recognised signs that are frequently not volunteered.
Reduced or changed fetal movements always warrant immediate contact, regardless of anything else.
What to hold onto
Being tired in pregnancy is expected. Being breathless on the stairs is not.
If you suspect low iron, ask about ferritin as well as haemoglobin, and ask for the number. Pair your iron-rich foods with vitamin C, keep tea away from meals, and if you are prescribed supplements that make you feel dreadful, ask for a gentler form rather than stopping.
And remember that this is not only about how you feel now. It is about what you carry into birth and the weeks afterwards, which is when you will need those reserves most.
A gentle note
If you would love support feeling genuinely well through your pregnancy, I am here. I offer warm, one-to-one pregnancy nutrition coaching alongside your midwifery care.
Written by
Brydee Thomas
Holistic health coach and founder of Radiant Bloom, supporting women through trying to conceive, pregnancy and the postpartum months. Evidence-based guidance, no programmes and no generic plans.