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Anaemia in Pregnancy _ Draft

Checked: 15-10-2024 by Rob Adams Next Review: 15-10-2026

Overview

Definition

Anaemia is defined as a haemoglobin (Hb) level two standard deviations below the normal for age and sex (1).

In pregnant women an Hb level of 110 g/L or more appears adequate in the first trimester, and a level of 105 g/L appears adequate in the second and third trimesters.

Postpartum Hb below 100 g/L.

Cause

The most common reason for developing anaemia during pregnancy is iron deficiency but folic acid and vitamin B12 deficiencies can also contribute to anaemia (3).

Prevention

Iron deficiency anaemia can be avoided by eating food that’s rich in iron. Including food rich in vitamin C with meals will also help with iron absorption. Iron is poorly absorbed when iron-rich foods are consumed together with tea, coffee, milk, chocolate or antacids/PPIs (3).

Daily iron and folic acid supplementation is currently recommended by WHO as part of antenatal care, to reduce the risk of low birth weight, maternal anaemia and iron deficiency. In the UK is suggested that the supplement contains 30 mg of iron along with 400 µg of folic acid (4). Supplements can be bought over the counter.

Treatment

If iron deficiency anaemia is diagnosed then treatment with iron replacement is advised.

First line treatment as per NICE guidelines is once daily dose of oral iron preferably on an empty stomach.
This should be continued for 3 months after iron deficiency has been corrected. NICE guideline recommends that haemoglobin levels should be checked after 2-4 weeks to assess the persons response to iron treatment.

The BNSSG formulary advises one of the following:

Ferrous sulphate 200mg OD (65 mg iron)
Ferrous fumarate 210mg OD (68 mg iron)
Ferrous gluconate 300mg OD (35mg iron)

If oral medications are not tolerated, or response is inadequate then consider the Treatment of Iron Deficiency in Adults pathway in the BNSSG formulary.

Referral

NICE guideline advises to refer pregnant women to obstetrics if there are significant symptoms and/or severe anaemia (haemoglobin less than 70 g/L), if pregnancy is at advanced gestation (over 34 weeks), or if there is failure to respond to a trial of oral iron (2).

Resources

(1) Anaemia - iron deficiency | CKS | NICE

(2) Management | Anaemia - iron deficiency | CKS | NICE

(3) Preventing and treating anaemia during pregnancy (imperial.nhs.uk) - patient leaflet from imperial college NHS trust (there is no BNSSG leaflet available).

(4) Antenatal iron supplementation (who.int)

(5) Anaemia: Antenatal and postnatal - UHBW guideline

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