Anaemia and iron tests in pregnancy

Pregnancy asks a lot of your iron stores, and tiredness can be easy to blame on everything else. Here’s how low iron is checked, what it feels like and what helps.

What is anaemia?

Anaemia means you don’t have enough red blood cells or haemoglobin. In the UK, a Rotherham NHS trust leaflet says the most common cause is not having enough iron, and that pregnancy raises how much iron you need, which can lower your iron stores. The NHS says untreated iron deficiency anaemia can raise the risk of complications before and after birth, so it’s worth finding and treating.

What does it feel like?

The NHS lists exhaustion, breathlessness, being aware of your heartbeat, paler skin and headaches. Many of these overlap with ordinary pregnancy tiredness, so don’t try to guess. If you’re worried, ask for a blood test.

When are you tested?

The NHS lists a blood test at 28 weeks that checks your health, iron levels and blood group. Some trusts also check earlier, and people at higher risk may be tested more often. Ask your midwife what your trust does. Your result is compared with cut-offs that depend on how far along you are, and your midwife or GP will tell you if yours is low. See blood tests in pregnancy.

If you’re anaemic

The Rotherham trust leaflet describes a plan like this, though your own team will tell you what applies to you:

Food. Iron-rich foods include red meat, fish, poultry, lentils, fortified cereals and leafy greens. Vitamin C helps your body absorb iron. The NHS says tea, coffee and milk and dairy can stop your body absorbing iron from other foods and tablets, so many people have them at a different time. See more on low iron in pregnancy.
Iron tablets. The NHS says treatment with iron tablets usually lasts about 6 months, and that taking tablets with or soon after food can reduce side effects. Ferrous sulfate is the recommended type. The leaflet suggests taking one with orange juice, or another vitamin C drink, an hour before breakfast, and no more than one a day. If side effects are a problem, it suggests every other day. Tummy pain, nausea, bloating, constipation and diarrhoea are common, and you may be offered a different type. Keep tablets away from children, because an iron overdose in a young child can be fatal.
Checking it’s working. The leaflet describes repeating the blood test 2 to 4 weeks after you start tablets, and carrying on for a further 3 months once your haemoglobin is normal to rebuild your stores.

If tablets aren’t working

The leaflet says you may be referred for iron through a drip (IV iron) if tablets aren’t working, you can’t tolerate them, they’re too slow, or there isn’t enough time before the birth. Occasionally a blood transfusion is needed if haemoglobin is very low or there is heavy bleeding at delivery. Ask your midwife or doctor to explain the options.

Check with your midwife or GP before you start iron tablets, rather than treating tiredness on your own.

Questions people ask

Can I just take iron tablets without a blood test?

It’s better to get tested first and let your midwife or GP advise, because the right dose depends on your results.

Do iron tablets make you constipated?

They can. The leaflet lists constipation and diarrhoea among the common side effects, and suggests taking a tablet every other day or trying a different type if they’re a problem.

Is feeling tired always anaemia?

No. Tiredness is very common in pregnancy, and anaemia is one possible cause. A blood test will tell you.

Will low iron affect my baby?

The NHS says untreated iron deficiency anaemia can raise the risk of complications before and after birth, which is why it’s treated.