Anaemia in pregnancy

AJGP Anaemia in pregnancy – https://www1.racgp.org.au/ajgp/2019/march/anaemia

definition

• haemoglobin (Hb)
  • <110 g/L at any stage of pregnancy
  • <100 g/L postpartum
• Physiological changes occur in the second trimester:
  • increasing plasma volume
  • increase in red cell mass
  • resulting in haemodilution – recognised as ‘physiological anaemia’
  • Therefore, a threshold of Hb <105 g/L in the second trimester is widely used throughout international guidelines

known risk factors

• younger age (<18 years)
• multiparity, previous iron deficiency
• shortened pregnancy interval
• disadvantaged socioeconomic status
• poor nutrition
• non-white ethnic origin
• haemoglobinopathy
• chronic blood loss
• parasitic disease

Interpretation of pathology results

Treatment recommendations of iron deficiency

Supplement name	Iron content	Elemental iron content
Ferro-Grad C	Ferrous sulfate 325 mg	105 mg
Ferro-Gradumet	Ferrous sulfate 325 mg	105 mg
Maltofer tablets	Iron polymaltose 370 mg	100 mg
Maltofer syrup	Per 5 mL = Iron polymaltose 185 mg	Per 5 mL = 50 mg
Ferro-F-Tab	Ferrous fumarate 310 mg	100 mg
Fefol delayed release iron	Ferrous sulfate 270 mg	87.4 mg
FGF	Ferrous sulfate 270 mg	80 mg
Ferro-Tab (PBS listed)	Ferrous fumarate 200 mg	65.7 mg
Ferro-Liquid	Per 5 mL = Ferrous sulfate 150 mg	Per 5 mL = 30 mg
Elivit	Ferrous fumarate 183 mg	60 mg
Elivit Women’s Multi	*	5 mg
Floradix	Ferrous gluconate	Per 10 mL = 7.5 mg
Spatone	*	25 mL sachet = 5 mg

Folate, B12 and micronutrient deficiencies

• Folate and vitamin B12 are essential for DNA synthesis and nuclear maturation

• Folic acid
  • Deficiencies are associated with
    • Neural tube defects
    • infertility
    • recurrent spontaneous abortion
    • preterm birth
  • 0.4 mg/day in the first 12 weeks
• B12
  • need 2.6 micrograms/day throughout the pregnancy
  • deficiency may also occur in the newborn and has been associated with neurological symptoms in infants exclusively breast-fed
  • routinely, assess B12 :
    • vegetarian and vegan diets
    • malabsorption disorders – Crohn’s disease and coeliac disease
    • autoimmune diseases
    • medication use (eg metformin)
    • bariatric surgery/gastric sleeve surgery.
  • Measurement
    • total B12 is first line but has limitations in diagnosis.
    • Active B12 is a more sensitive marker.
  • Treatment
    • There remains a lack of evidence guiding optimum treatment of B12 deficiency in pregnancy in regard to oral versus intramuscular replacement.
    • Decision on administration route must be based on patient preference, reason for B12 deficiency and the possibility of poor oral absorption.
    • Parenteral therapy with hydroxocobalamin (1000microg/1mL), given by intramuscular injection, once weekly for 3 weeks is commonly used.

Haemoglobinopathies

• thalassaemias = inherited disorder associated with impaired synthesis of one or more of the globin chains, with alpha and beta thalassemia being most common.
• haemoglobin variants – sickle cell disease (SCD)
  • group of inherited autosomal recessive disorders that affect haemoglobin structure
  • Folic acid 5 mg daily should be given both preconceptually and throughout pregnancy in women with SCD

Summary of significant haemoglobinopathies that may affect the woman and fetus
Haemoglobin disorder	Maternal genotypes that may affect the woman and the fetus (depending upon partner study results)
Alpha thalassaemia	αα/α-, αα/–, α-/α- (carrier or minor trait) α-/– (haemoglobin H disease) –/– (Barts hydrops generally resulting in death in utero)
Beta thalassaemia	β/β0, β/β+ (carrier or minor trait) β+/β+, β0/β+ (Beta thalassemia intermedia) β0/β0 (Beta thalassemia major)
Haemoglobin S	AS (sickle cell trait) SS SC S/β thal. SD S/O-Arab (sickle cell disease)
Haemoglobin E	AE (carrier) E/β thal. (ranges from E/β thal. intermedia to major)

Risk groups for haemoglobinopathies
Clinically significant haemoglobin disorder	Area of prevalence/family origin
Alpha thalassaemia	Southeast Asia India Middle East Africa Mediterranean
Beta thalassaemia	Southeast Asia Indian subcontinent Middle East Africa Mediterranean
Haemoglobin S	Africa including North Africans African American African Caribbean British African or any other African ethnicity

Infections

Although not as common, maternal helminthic infection with Ascaris lumbricoides, Trichuris trichuria or hookworms carries increased risk of anaemia during pregnancy.

Treatment with antihelminth therapy is considered safe in pregnancy, but iron replacement is still often required to correct iron deficiency.

Malaria, despite being rarely seen in Australia, should be considered in anaemia, particularly as many women in pregnancy still travel to risk areas and antimalarial prophylaxis is limited in this group of travellers. Severe anaemia, as acute haemolytic anaemia, has been reported with malaria infection.

Human immunodeficiency virus (HIV) is an independent risk factor for anaemia in pregnancy and is thought to be caused through chronic inflammation.