Pathophysiologic and anaesthetic considerations in iron deficiency anaemia and pregnancy; An update

Anaemia is common during pregnancy, especially in low- and middle-income countries, and iron deficiency is the most common cause of anaemia worldwide. Symptoms relating to iron deficiency can be diverse, which relate to the depletion of cellular Fe function in different tissue organs and may exist long before Fe deficiency restricts erythropoiesis and anaemia develops. It is important to understand the pathophysiological and adaptation changes occurring during anaemia as long-standing changes affect the various organ systems and may impact both maternal and neonatal outcomes. There is growing evidence linking maternal IDA with subsequent neonatal cognitive and neurobehavioral outcomes, which makes it imperative that IDA should be treated early in pregnancy. Preoperative optimization with iron therapy (oral or parenteral) and erythropoiesis-stimulating agents vs replenishing O2-carrying capacity by transfusion must always be balanced against transfusion-associated risks. The anaesthetic management in parturients with severe anaemia depends on a multitude of factors, such as severity of iron deficiency anaemia, co-morbid diseases, extent of physiological compensation, and type and nature of anticipated haemorrhagic loss. This review summarizes the pathophysiological changes and adaptations consequent to oxygen delivery and iron homeostasis, therapeutic management, and anaesthetic challenges in pregnancy with IDA. It is based on electronic search strategies from Ovid Medline, Ovid Embase and PubMed (up to June 2021) along with relevant college and society web-based resources, including Royal College of Obstetricians and Anaesthesiologists, National Institute for Health and Clinical Excellence College and Society (NICE), Patient Blood Management Guidelines and American College of Obstetricians and Gynaecologists (ACOG) practice bulletins.