Display Patient Information Leaflets

Date issued: August 2025  

For review: August 2027 

Ref: C-627/CS/Maternity/Iron Deficiency and Anaemia in Pregnancy

PDF: Iron Deficiency and Anaemia in pregnancy.pdf [pdf] 253KB

What is anaemia? 

Anaemia is when the level of haemoglobin in your blood is lower than normal. Haemoglobin carries oxygen from your lungs to cells around your body. If your haemoglobin count is low, then your body does not work as well as it should. Iron is one of the minerals that your body needs to produce haemoglobin. 

What is iron deficiency?

Iron deficiency is when your stores of iron (ferritin) within your body are too low. This can happen before you develop anaemia, so your haemoglobin levels would be normal when measured. It can also occur alongside anaemia. You are at high risk of developing anaemia during your pregnancy if your iron stores are low.

A healthy diet is generally enough for most people to avoid iron deficiency and anaemia. The main sources of iron in your diet are red meats, poultry, fish, beans, lentils, eggs and dark leafy vegetables. 

How can anaemia affect me? 

Anaemia can cause tiredness, breathlessness, fainting, headaches and your heart to beat faster. 

Mild anaemia is common during pregnancy and your haemoglobin and ferritin levels will be routinely checked at your first pregnancy appointment and at 28 weeks. 

During pregnancy, you may not get enough iron to keep pace with your increasing blood supply and the needs of your growing baby. You also need more iron when they are breast feeding and some babies need extra iron too. 

Why do I need to have treatment for anaemia?

All pregnant patients are offered routine blood tests to check for iron deficiency and anaemia at the beginning of pregnancy and at about 28 weeks gestation. It is important to treat iron deficiency and anaemia in pregnancy for many reasons. If you are iron deficient, you are likely to develop anaemia during your pregnancy due to the increased iron demands. There is always a risk of bleeding when you have a baby and if you are already anaemic this can increase your risk of bleeding and make it more likely that you will need a blood transfusion. Anaemia has also been linked to depression, delayed wound healing and making it more difficult to fight infection. Babies can be anaemic too and there is a possibly increased risk of prematurity, having a small baby or your baby not growing as much as we would expect.

Some people are more at risk of being iron deficient and/or anaemic and these include, vegetarians, teenagers, those expecting twins, those who previously had very heavy periods and those who had a baby less than a year ago or have had many children. Some people are not at an increased risk of anaemia but are at a higher risk of bleeding, in this case you may also be advised to take supplements during pregnancy. 

Iron replacement 

At the beginning of pregnancy, your midwife will give you a box of oral iron tablets. Once your midwife or doctor has reviewed your blood results, they will advise you if you need to start taking the iron tablets. This will help to restore your iron stores and haemoglobin level instead of an iron infusion or a blood transfusion. It will take longer for you to feel completely well but you avoid the minimal risks associated with an iron infusion or a blood transfusion.

For the tablets to work well, it is advisable to:

• Have a source of vitamin C (such as a small glass of fresh orange juice or a vitamin C supplement) at the same time. 

• Iron tablets are best taken on an empty stomach. 

• Tea and coffee reduce iron absorption from your diet and so should be avoided at mealtimes and when you take the iron tablets. 

• Heartburn treatments such as Gaviscon® or Omeprazole® also prevent the absorption of iron so should be taken at a different time of day to the iron tablets.

You may be advised to take iron tablets either on alternate days or once daily depending on your gestation. This advice may differ from the details in the information leaflet provided with your medicine but follows latest evidence. Alternate day dosing can help to reduce side effects and improve absorption.  When you don’t properly absorb the iron, it remains in your intestines and causes constipation, an upset stomach, and black stools, in addition to not treating your iron deficiency or anaemia. If you are absorbing all your iron, you should not get these side effects, and your haemoglobin level should start to rise within two weeks.

You may also be advised to take folic acid, in addition to taking iron, to raise your haemoglobin level. Once your level of haemoglobin is normal you will need to continue taking supplements for at least a further 3 months (if you are pregnant) or 6 weeks (if you have had the baby) to build up your iron stores. 

Iron infusion 

If you are unable to take iron tablets or your anaemia doesn’t respond to iron tablets, you may be offered an iron infusion (‘Ferinject’). Occasionally you will be offered an infusion if you are approaching your due date as this treatment works more quickly than giving you tablets. 

The iron is given through a drip in your arm. This can be given after the first 3 months of pregnancy. It is safe for you and your baby. 

Most people who receive iron infusions do not have any side effects however the main side effects of having an iron infusion are explained below.

Side effects of iron infusion

These are often, mild and include:

•  Headaches, 

•  Nausea, 

•  Soreness or redness around the injection site and

•  Elevated blood pressure. 

These side effects do not tend to last very long and usually don’t require any other treatment. 

There is a small risk of long-term skin staining with iron infusions. In very rare circumstances this can be permanent however in most cases this staining will fade over time.

Rare reactions 

Iron infusions can very rarely cause anaphylaxis, also known as “severe hypersensitivity reaction”. This happens to less than 5 people per 10,000 (0.045%) the IV iron infusion prescribed at UHP The symptoms are swelling of the face, mouth and tongue and possibly causing difficulty in breathing. 

What happens when you have the iron infusion? 

After the drip is placed in your arm and the iron infusion if started it will take around 15-30 minutes to be given. You will be observed in the department for another 30 minutes after the infusion is complete. 

Important things to be aware of with infusions

The iron medication is brown in colour and so it is very important that when you have the intravenous (IV) infusion of iron that you keep your arm still and not bend it as this may lead to leaking of the iron into the surrounding tissue. This may cause irritation of the skin and long-lasting discolouration of the skin. 

Please inform the staff immediately if you have pain at the site of the “drip”. You will be monitored for this and treatment provided if required. If after you go home, you have any concerns then please contact triage. 

Do I need more than one dose of iron infusion? 

Some people need to return for a second dose. This will be discussed with you and depends on how anaemic you are. You are advised to avoid taking oral iron supplements for 7 days after the final infusion and then to recommence taking iron as prescribed every other day.

You will need to have a blood test 2 weeks after the infusion to make sure that your anaemia has responded to the treatment.