Anaemia in Pregnancy: Haemoglobin Thresholds, Iron Supplements and When to Escalate

What is pregnancy anaemia and how is it diagnosed?

Anaemia in pregnancy means that the red cells in your blood are insufficient to carry enough oxygen for you and your growing baby. Iron deficiency is by far the most common reason, but deficiencies in folic acid or vitamin B12, and inherited conditions such as thalassaemia, can also be responsible.

The World Health Organization defines pregnancy anaemia as haemoglobin below 11 g/dL in the first and third trimesters, and below 10.5 g/dL in the second. These thresholds are lower than those used outside pregnancy because blood volume naturally expands during pregnancy, which dilutes the haemoglobin concentration.

Diagnosis starts with a full blood count (CBC). If the haemoglobin is low and the red cells are small and pale, iron deficiency is the likely cause. A ferritin test confirms whether iron stores are truly depleted, because ferritin is the most sensitive marker of stored iron, and it can fall weeks before the haemoglobin does.

Why is pregnancy anaemia so common in the region?

Pregnancy sharply increases the body's demand for iron: the mother's blood volume expands by around 50 percent, and the growing fetus draws on maternal stores to build its own supply, which will sustain it through the first six months of life before solid foods begin. This demand is very hard to meet through diet alone.

A 2024 study published in BMC Public Health examining Jordanian pregnant women found that low dietary diversity was directly linked to higher rates of iron deficiency anaemia. Diets heavy in bread and starches with limited animal protein and leafy green vegetables put women at particular risk, and this dietary pattern is common across much of the region.

Closely spaced pregnancies compound the problem. Each pregnancy draws heavily on iron stores, and if the gap between births is short, the mother may enter the next pregnancy already depleted, even if her haemoglobin appears normal on a routine test.

Economic pressures and limited access to regular antenatal care further complicate matters. When blood tests are missed or delayed, anaemia is sometimes discovered late in the third trimester, when there is less time for oral iron to work and intravenous treatment becomes the more practical choice. This is a common scenario in settings where lab access is limited or costs are a barrier.

Iron deficiency versus iron deficiency anaemia: what is the difference?

Iron deficiency and iron deficiency anaemia are not the same thing, and the distinction matters. Stores can be depleted while haemoglobin still appears in the normal range. This stage, sometimes called latent iron deficiency, causes fatigue, poor concentration and reduced exercise tolerance, but it will not appear as anaemia on a standard blood count.

In pregnancy, a ferritin level below 30 nanograms per millilitre is generally considered evidence of depleted stores, even if haemoglobin is still above the threshold. Many clinicians start treatment at this point because demand will only rise as pregnancy progresses.

Women who carry the thalassaemia trait (Thalassaemia Minor) will have small, pale red cells even when iron stores are normal. Distinguishing the two conditions requires haemoglobin electrophoresis (Hb Electrophoresis). If you know you carry the trait, tell your doctor before any treatment is prescribed, so the right test is done first.

How to take oral iron so it actually works

Oral iron comes in several forms: ferrous sulphate (Ferrous Sulphate) is the most widely available and cheapest, while ferrous bisglycinate (Ferrous Bisglycinate) causes fewer stomach side effects and is easier to tolerate. Your doctor or pharmacist will advise which is available locally and appropriate for you.

The single most important thing you can do is get the timing right. Iron taken on an empty stomach an hour before a meal, with a glass of orange juice or any other vitamin C source, absorbs far better than iron taken with food. Tea, coffee, cow's milk and calcium supplements all bind to iron in the gut and can cut absorption dramatically. If a cup of tea is part of your morning routine, which it is for many women in the region, try to leave at least two hours between the tea and the iron.

A 2024 Cochrane systematic review of daily oral iron supplementation in pregnancy confirms improved haemoglobin levels and a lower risk of low birthweight in supplemented women. Some evidence suggests that taking iron every other day rather than daily reduces gastrointestinal side effects while preserving most of the benefit, but this schedule should be agreed with your doctor.

Which foods support iron levels during pregnancy?

Dietary iron comes in two forms. Haem iron (Heme Iron), found in red meat, poultry and fish, is the most readily absorbed. Chicken liver and beef liver are among the richest sources and are widely available and affordable across the region. Non-haem iron (Non-heme Iron), found in lentils, chickpeas, spinach, and eggs, absorbs less efficiently but still contributes meaningfully to your total intake, particularly when eaten alongside a vitamin C source.

Practical combinations worth building into your meals include lentil soup with a squeeze of lemon, eggs with tomatoes, and hummus with fresh parsley. Adding these to the main meal rather than relying on supplements alone helps, though in most cases supplementation is still necessary to meet the higher demands of the second and third trimesters.

The foods most worth limiting around iron-rich meals are black and green tea, which contain tannins that bind iron in the gut. This does not mean cutting out tea entirely, but simply timing your cup so it does not coincide with your iron-richest meal of the day.

Calcium supplements are another common source of interference. If your doctor has recommended both calcium and iron, the simplest fix is to take iron first thing in the morning on an empty stomach and calcium in the evening with food. This small scheduling change improves absorption of both without adding any cost or complexity.

When is intravenous iron the right choice?

For some women, oral iron is not enough or cannot be tolerated. A randomised controlled trial published in the American Journal of Perinatology in 2022 found that intravenous iron raised haemoglobin faster than oral iron, making it the preferred option when anaemia is severe or when delivery is approaching and there is not enough time for oral supplementation to work.

Intravenous iron is generally considered when haemoglobin falls below 8 to 9 g/dL, when haemoglobin has not improved after four weeks of oral iron taken correctly, or when side effects from oral iron are intolerable. It is given in a clinic or hospital setting with a short period of observation, and it is considered safe from the second trimester onwards.

Commonly available forms include ferric carboxymaltose (Ferric Carboxymaltose) and iron sucrose (Iron Sucrose). The choice depends on what is available locally and your clinical situation. The infusion usually takes between 15 minutes and one hour depending on the formulation used.

What are the risks of severe untreated anaemia?

Mild anaemia that is detected and treated early carries very little long-term risk. Severe untreated anaemia is a different matter. A 2024 review in Annals of Hematology reports that severe iron deficiency anaemia in pregnancy is associated with preterm birth, low birthweight and impaired oxygen delivery to the fetus, which can affect neurological development.

There is also a risk to the mother. Women who enter delivery room with severe anaemia have much less reserve to handle normal blood loss during childbirth. Even a routine delivery involves some blood loss, and this can push an already anaemic woman into a dangerous range quickly, sometimes requiring a blood transfusion.

This is why most obstetric guidelines aim to have haemoglobin above 10 g/dL by at least 36 weeks of pregnancy, giving enough time to build stores before delivery.

Monitoring treatment and knowing when you have improved

After starting oral iron, haemoglobin is expected to rise by about 1 to 2 g/dL every four weeks in women who are responding. Your doctor will recheck your blood count after a month to confirm this improvement. If it has not moved, the reasons to consider include whether you are taking the iron correctly, whether the dose is adequate, or whether there is a second cause of anaemia that has not yet been identified.

After delivery, iron stores need to recover from the blood lost during childbirth and from the demands of breastfeeding. Many doctors recommend continuing an iron supplement for at least three months after delivery in women who had anaemia during pregnancy.

In areas where regular clinic access is difficult, bringing your blood test result to any available health centre for interpretation is an important step. Do not rely on pallor or tiredness alone to judge your own levels. Pallor of the inner eyelids, a common sign of anaemia, only becomes visible when haemoglobin is already quite low, by which point the stores have been depleted for some time.

If you have access to a haemoglobin meter or a community health worker who can do point-of-care testing, this can be useful for interim monitoring between full laboratory visits. These devices are not as accurate as a full blood count done in a properly equipped laboratory, but they are better than no monitoring at all, and can guide the decision on whether a full test is needed urgently.

Questions worth raising at your next appointment

Many women have a haemoglobin checked without knowing whether ferritin was also measured. It is worth asking your doctor directly: has my ferritin been checked? Is my current haemoglobin level one that needs treatment, or is it within an acceptable range for this trimester? Is the iron dose I have been given appropriate for how low my stores are?

If you have tried iron supplements before and found the side effects difficult, or if you have been quietly reducing your dose without telling your doctor because of nausea or constipation, this is important information to share. A dose that is halved or skipped frequently will not produce the expected rise, and your doctor can offer alternatives, whether a gentler form of iron, a different dosing schedule, or a switch to intravenous therapy.

For women planning a future pregnancy, it is worth checking that iron stores have fully recovered before conceiving again. A ferritin test three to six months after delivery gives a clear picture of where you stand. Entering the next pregnancy with replenished stores reduces the risk of going through the same pattern of anaemia in the early second trimester, when demand rises fastest.

Finally, if your family has a history of thalassaemia, sickle cell anaemia or other inherited blood conditions, let your midwife or obstetrician know even if you have not had genetic testing. These conditions interact with iron status in ways that change the treatment approach, and it is much better to have the right workup early than to discover the diagnosis after several months of iron treatment that was not needed.

Sources

• Lopez A, Cacoub P, Macdougall IC et al: Iron deficiency anaemia, Lancet (London, England), 2016
• Finkelstein JL, Cuthbert A, Weeks J et al: Daily oral iron supplementation during pregnancy, The Cochrane database of systematic reviews, 2024
• Kirthan JPA, Somannavar MS: Pathophysiology and management of iron deficiency anaemia in pregnancy: a review, Annals of hematology, 2024
• Benson AE, Shatzel JJ, Ryan KS et al: The incidence, complications, and treatment of iron deficiency in pregnancy, European journal of haematology, 2022
• Lewkowitz AK, Stout MJ, Cooke E et al: Intravenous versus Oral Iron for Iron-Deficiency Anemia in Pregnancy (IVIDA): A Randomized Controlled Trial, American journal of perinatology, 2022
• Al-Bayyari N, Al Sabbah H, Hailat M et al: Dietary diversity and iron deficiency anemia among a cohort of singleton pregnancies: a cross-sectional study, BMC public health, 2024
• World Health Organization: Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity, WHO/NMH/NHD/MNM/11.1, 2011