Iron and pregnancy: A dietitians guide to what your results really mean.

Sophie Mumby, Registered Dietitian (HCPC)

If you've had your bloods taken recently and been told your haemoglobin is "a bit low" or your ferritin needs "keeping an eye on", it's natural to feel a flutter of worry. Let's unpick what these numbers mean.

Haemoglobin is the protein in your red blood cells that carries oxygen around your body. In pregnancy, your blood volume expands significantly, and plasma increases more than red blood cells do. This dilutes your haemoglobin, so a mild dip can be a normal physiological change rather than a problem. In the UK, anaemia in pregnancy is generally defined as haemoglobin below 110 g/L in the first trimester and below 105 g/L in the second and third trimesters.

Ferritin is your body's iron storage protein. It's often a more sensitive early signal than haemoglobin, because your stores can run low well before your haemoglobin drops. Your midwife or GP will interpret it alongside your other results, as ferritin can also be raised by infection or inflammation.

One good way of thinking about ferritin and haemoglobin is in terms of a bank. Ferritin is your savings account, it stores your body's iron waiting for you to "withdraw" it into cash to spend. Haemoglobin is your spending money and it travels around in your blood providing oxygen to your cells.

Why iron matters now. Your body is building a placenta, supporting your baby's growth and preparing for blood loss at birth. Low iron can leave you exhausted, breathless, dizzy or struggling to concentrate. Those symptoms overlap with normal pregnancy, which is why testing matters more than guessing.

Food first, but not food only. Iron-rich foods include red meat, poultry, fish, eggs, beans, lentils, tofu, fortified breakfast cereals, dark green leafy vegetables and dried apricots. Iron from plant foods is absorbed less readily, so pair it with vitamin C (a glass of orange juice, peppers, berries) and try to keep tea and coffee away from iron-rich meals. Avoid liver and liver products in pregnancy because of their high vitamin A content.

If your ferritin or haemoglobin is low, diet alone is rarely enough to correct it. Your healthcare team may recommend an iron supplement, often taken on alternate days, with a source of vitamin C, which can improve absorption and reduce side effects like constipation and nausea.

If eating feels hard. Nausea, vomiting, food aversions, hyperemesis, restriction or a history of an eating disorder can all make meeting your iron needs more difficult. This is common, and it isn't a failing. Tell your midwife or dietitian. We can look at what feels manageable, such as small, frequent, tolerable choices, and make sure your bloods are monitored closely. You deserve support without judgement.

This post is general information and not a substitute for personalised medical advice. Please speak to your midwife, GP or dietitian about your own results.