Why Iron Deficiency in Pregnancy Matters So Much

Q: How do I know if my tiredness in pregnancy is caused by low iron?

Tiredness is common in pregnancy for all sorts of reasons, and the kind linked to iron deficiency anaemia tends to be more stubborn and harder to explain away. It can come with breathlessness, dizziness, or a racing or fluttering heartbeat. The only way to know for sure is a blood test. Your midwife offers this at your booking appointment and again at 28 weeks. If your symptoms feel significant before then, contact your midwife or GP to ask for an earlier check.

Q: Can I take iron supplements in pregnancy without a prescription?

UK guidance does not recommend starting iron supplements in pregnancy without a confirmed diagnosis of iron deficiency anaemia. Taking iron tablets when your levels are already fine can cause side effects and is not advised. If you are worried about your levels, speak to your GP or midwife, who can test your blood and prescribe iron if you need it.

Q: Which foods are best for iron during pregnancy?

Red meat, poultry, and fish give you haem iron, the form your body absorbs most easily. If you eat less meat, pulses such as lentils and beans, dark green leafy vegetables, nuts, and fortified cereals all add non-haem iron. Eating these with a source of vitamin C, like tomatoes, peppers, or orange juice, helps your body take up more of the iron from plant foods.

Q: Does drinking tea or coffee affect iron in pregnancy?

Yes. Tea and coffee contain tannins that lower iron absorption, and high-calcium foods such as milk can do the same. You do not need to cut them out completely, but it helps to keep them away from an iron-rich meal or an iron tablet. Leaving around an hour either side of eating can reduce how much they interfere.

Pregnant woman texting on her phone while holding a bottle.

The information in this article is for general informational purposes only and does not substitute for professional medical or dietary advice, particularly during pregnancy. If you are outside the UK, please consult your local doctor, midwife, or healthcare provider for guidance that reflects your country's recommendations.

There is tired, and then there is the kind of exhaustion that makes a short walk feel like a long one, and holding a normal conversation harder than it should be. When that level of tiredness arrives during pregnancy, it can be easy to put it down to the work your body is already doing. If a blood test comes back showing low iron, that exhaustion has a specific cause: iron deficiency anaemia in pregnancy. Shortness of breath, dizziness, and a heart that flutters or races for no obvious reason can be other signs your iron has dropped too low. If any of these feel familiar, raise them with your midwife or GP.¹

Why do iron needs rise so much in pregnancy?

Pregnancy raises how much iron you need, for two reasons that connect. The amount of blood moving around your body grows by roughly half, and all that extra blood needs iron to carry oxygen. At the same time, your growing baby and placenta draw on your own iron stores to build their supply of red blood cells. Your body puts the baby first, so your stores can run down faster than you feel it happening.²

When your stores cannot keep up with these demands, iron deficiency anaemia can set in. The effects reach beyond tiredness. Low iron in pregnancy can raise the chance of complications during and after birth, including a greater chance of needing a blood transfusion. Your baby may also arrive with lower iron reserves, which can affect their health in the early months. Talking through your own risk with your midwife or GP is the clearest way to understand what this means for you.³

How are iron levels are checked in the UK?

In the UK, your iron is checked as part of routine antenatal care. You are offered a blood test at your first booking appointment, and again at 28 weeks. Those two points are chosen to catch low iron early and at the stage when demand is highest. Most iron deficiency anaemia in pregnancy turns up through this pathway, so you do not need to ask for a separate test unless symptoms come up between appointments.⁴

Where does iron comes from in your diet?

Iron in food comes in two forms, and your body takes them up differently. Haem iron, the kind in animal foods, is absorbed easily. Non-haem iron, the kind in plant foods, is absorbed less readily, though it still counts, especially if you eat little or no meat.⁵

Variety of fresh vegetables and lean meats on a tray.

Haem iron in meat and fish

Red meat such as beef and lamb
Poultry
Fish and seafood

Non-haem iron in plant foods

Pulses: beans, lentils, chickpeas
Dark green leafy vegetables: spinach, kale
Nuts and seeds
Fortified breakfast cereals

What helps and hinders iron absorption?

Vitamin C is one of the best ways to lift how much non-haem iron your body takes from a meal. Pairing a source of vitamin C with iron-rich plant foods makes a real difference. A glass of orange juice, some sliced tomatoes, or red or yellow peppers alongside lentils or spinach can noticeably improve how much you absorb.⁶

Some everyday foods and drinks pull in the other direction. Tea and coffee contain tannins that lower how well you absorb iron. Milk and other high-calcium foods can get in the way too. The useful move is about timing rather than cutting things out. Try not to have tea, coffee, or a large glass of milk at the same time as an iron-rich meal or an iron tablet. Leaving a gap of around an hour either side can help your body make better use of the iron in your food.⁷

Iron supplements in pregnancy and the UK approach

In the UK, iron supplements are not handed to everyone who is pregnant. The approach in UK guidance is to screen for anaemia through the blood tests above, and to prescribe supplements only once iron deficiency anaemia is confirmed. When treatment is needed, the first option is usually oral iron tablets prescribed by a GP or midwife. Starting iron on your own is not advised, since taking it without a confirmed deficiency carries its own risks.⁸

Frequently Asked Questions

How do I know if my tiredness in pregnancy is caused by low iron?

Can I take iron supplements in pregnancy without a prescription?

Which foods are best for iron during pregnancy?

Does drinking tea or coffee affect iron in pregnancy?

Your iron will be checked as part of your routine antenatal blood tests at your booking appointment and at 28 weeks. If symptoms come up between those appointments, or you want to talk through your diet or supplement options, your midwife or GP is the right place to start.

Sources

[1] Pregnancy - NHS

Feeling excessively tired during pregnancy, beyond normal pregnancy fatigue, can be a primary symptom of iron deficiency anaemia. Other symptoms include shortness of breath, dizziness, and heart palpitations.
[2] NHS – Vomiting and Morning Sickness in Pregnancy

The growing baby and placenta draw directly on maternal iron stores to build their own supply of oxygen-carrying red blood cells.
[3] Tommy's – Morning Sickness Tips and Treatments

The baby may also be born with lower iron reserves, which can affect their health in the early months.
[4] Pregnancy NHS Source

In the UK, a blood test is offered at the first booking appointment and again at 28 weeks of pregnancy to check iron levels.
[5] NHS – Vomiting and Morning Sickness in Pregnancy

Non-haem iron, found in plant-based foods such as pulses, dark green leafy vegetables, nuts, and fortified cereals, is absorbed less readily.
[6] NHS – Vomiting and Morning Sickness in Pregnancy

Vitamin C significantly helps the body absorb iron from plant-based sources; consuming vitamin C alongside iron-rich plant foods can increase iron uptake.
[7] NHS – Vomiting and Morning Sickness in Pregnancy

Avoiding tea, coffee, or high-calcium foods at the same time as iron-rich meals or iron supplements can help the body make better use of dietary iron.
[8] Tommy's – Morning Sickness Tips and Treatments

When treatment for iron deficiency anaemia is needed in pregnancy, the first-line option is oral iron tablets.
[9] WHO — Antenatal iron supplementation

In the United States, universal low-dose iron supplementation within a standard prenatal vitamin is common from the first antenatal appointment, regardless of whether a deficiency has been diagnosed.