Iron and early pregnancy: what’s worth knowing

Pregnancy loss is never your fault. Nothing in this post is meant to suggest otherwise, or to say that iron, or anything else, is the reason for a loss. It’s just general information about iron.

Iron and ferritin

Ferritin is a protein that stores iron, and a ferritin blood test can show how much iron you have stored in your body.1 People who menstruate often ask me about iron, and it’s easy to overlook when the focus is on fertility.

How much iron do people need?

Health Canada’s reference values set the recommended daily amount of iron at 18 mg for adult women, and 27 mg during pregnancy.2 That’s one reason Health Canada’s pregnancy guidance suggests a daily multivitamin with folic acid and iron.3

Testing, and what we don’t know

Whether everyone should be screened for low iron during pregnancy isn’t settled. The US Preventive Services Task Force concluded in 2024 that the current evidence is insufficient to assess the balance of benefits and harms of screening for iron deficiency and iron deficiency anemia in pregnant people.4 A Cochrane review of daily iron supplements in pregnancy found they probably reduce iron-deficiency anaemia at term, with probably little to no difference in preterm birth.5

Research on iron and early pregnancy loss specifically is still developing, and I won’t make promises about it here. What I can say is that if you’re trying to conceive, or you’ve had a loss, it’s reasonable to ask your care team about a ferritin test and a complete blood count, and to talk through what the results mean for you.

What the research says, at both ends

A 2020 review notes that iron deficiency is associated with adverse pregnancy outcomes, including increased maternal illness, low birthweight, prematurity and growth restriction.6 Iron deficiency without anemia is at least twice as common as iron deficiency anemia, and it’s often missed.7

High iron stores aren’t better, though. In a Danish study of 699 people, higher ferritin in early pregnancy went with more gestational diabetes,8 and a meta-analysis of 10 studies found the same pattern while asking for more research.9 In an Ontario study of nearly 90,000 births, a very high ferritin before pregnancy (112 µg/L or more, compared with 16.9 µg/L or less) went with a higher chance of preterm birth.10 These are associations, and ferritin also rises with inflammation, so a number needs context.

In my practice, I offer an iron check (hemoglobin and ferritin) to everyone I see in pregnancy, rather than waiting for symptoms, and I check before suggesting extra iron. That goes further than the guidelines above, and you can always say no.

If your iron is low

The options, such as food, iron taken by mouth, or in some cases iron given by IV, depend on your levels, your symptoms and what’s safe for you. I don’t provide IV treatment, so if that’s something to consider, your doctor or fertility clinic can guide you.

If you’d like to go through your lab results, or just talk, you’re welcome to book a visit. I’ll be gentle.