2.1.3. Iron deficiency is already advanced by the time anaemia is detected and has a symptom burden even when anaemia is not clinically apparent. Iron deficiency should be anticipated and treated before the patient develops anaemia.

2.1.4. Effective management of anaemia and iron deficiency is essential to prevent adverse maternal and fetal outcomes and will reduce the need for allogeneic blood transfusion. Blood transfusions entail a number of known risks (e.g. transmission of infectious agents, transfusion reactions, ABO mismatch, transfusion-related acute lung injury, transfusion-associated circulatory overload) and lesser-known consequences such as immunomodulation, increased incidence of infections and cancer recurrence (Goodenough and Shander, 2012).

2.1.5. Without supplementation, 80% of women at term will have no detectable iron stores and it will take 2 years of normal dietary iron to replace the iron lost with each pregnancy (De Leeuw et al. 1966).

2.1.6. Treating iron deficiency has maternal benefits: reduced fatigue, reduced blood loss and PPH risk, reduced hospital stay, reduced risk of infection, reduced postnatal depression, reduced healthcare costs (Bensen et al 2021) and neonatal benefits: reduced risk of prematurity, reduced risk of growth restriction, reduced incidence of low Apgar scores, improved infant neurodevelopment and higher incidence of breast feeding (Rukuni et al 2015).

2.1.7. In IDA there is shortage of iron stores. Iron depletion reduces iron availability for red cell production (erythropoiesis), resulting in decreased haemoglobin (Hb), and decreased oxygen delivery to tissues.

2.1.8. The effects of IDA on the pregnant woman may include increased susceptibility to infections, physical weakness, preterm labour, increased PPH risk, postnatal depression, and low birth weight babies.

2.1.9. There is little information regarding the Hb threshold below which mortality increases, although this may be as high as 89 g/l, which is associated with a doubling of the maternal death risk in Britain (Brabin et al. 2001). Prevalence of adverse pregnancy outcomes (GDM, polyhydramnios, preterm birth, low birth weight) are increased below 110 g/l (Lin et al 2018).

2.1.10. 80% of the iron absorbed by the fetus happens in the 3rd trimester. Hence, a low ferritin at 28 weeks is likely to get significantly worse by term without adequate supplementation.

2.1.11. The purpose of this guideline is to ensure women have good compliance with oral preparations of iron, understand how to take the drug and its side effects and that these need to be tried before IV iron is trialled. IV iron can come with significant side effects and costs and therefore all attempts to improve oral iron uptake need to be undertaken first.

2.1.12. This guideline will hopefully demonstrate when to refer to obstetrics and reduce the frequency of referrals needed.