Anaemia in Pregnancy

Question 1

Define

Answer 1

Pregnant women with mean value of Hb <110g/L (1st trimester)

• < 110 g/L in 1st trimester
• < 105 g/L in 2nd/3rd trimester
• < 100 g/L postpartum
• < 70 g/L – URGENT REFERRAL

· Prevalence varies by socio-economic status – recent studies = ~20%

Microcytic causes: iron deficiency

Macrocytic causes: folate or Vitamin B12

Question 2

Epidemiology

Answer 2

Iron deficiency is the COMMONEST cause of anaemia

Anaemia worsens in multiple pregnancies

Folate deficiency is common with anti-epileptic drugs

Question 3

Aetiology

Answer 3

Physiological changes in pregnancy:

• 50% increased plasma volume by 34 weeks – dilutional anaemia
• Fall in haemoglobin, haematocrit, red cell volume (relatively)
• No change in MCH and MCHC
• Progressive fall in platelet count but remain in normal limits
• 2-3 fold increase in iron requirement
• 10-20 fold increase in folate requirement

Several types of anaemia including iron-deficiency, folate-deficiency, B12 deficiency

• Iron deficiency – blood loss, inc. use, dec. absorption, dec. intake, haemolysis
  
  • Hypochromic microcytic anaemia, pencil cells
• Folate – green leafy vegetables -> lack increases neural tube defects – diet, demand, malabsorption, drugs
  
  • Megaloblastic anaemia (hypersegmented neutrophils, macrocytosis, thrombocytopaenia, leucopaenia)
• B12 – vegans, poultry, dairy, eggs -> lack increases neural tube defects – diet, malabsorption
  
  • Megaloblastic anaemia (hypersegmented neutrophils, macrocytosis, thrombocytopaenia, leucopaenia)

Question 4

Risk factors

Answer 4

Low iron prior to pregnancy

Pre-existing blood conditions e.g .SCD, thalassaemia

Factors affecting iron absorption:

• Inflammatory bowel disease
• Coeliac disease
• Bowel surgery

Multiple pregnancy

< 20 years old and pregnant

Gave birth to previous child < 1 year ago

Anaemia in previous pregnancy

Diet

Question 5

Symptoms and Signs

Answer 5

Presenting Symptoms

• Tiredness, lethargy
• Dizziness, fainting
• Headache
• Irritability
• SOB
• Tachycardia/ tachyponoea
• Trouble concentrating

Signs:

• B12-specific – glossitis, depression, psychosis/dementia, paraesthesia, peripheral neuropathy
• SCDC (subacute combined degeneration) = loss proprioception/vibration -> full paralysis

 

Maternal anaemia

• Pale
• Breathless
• Tachycardia
• Heart palpitations

Foetus anaemia

Note: these are not usually obvious unless foetal Hb < 60g/L

• Polyhydramnios
• Enlarged foetal heart
• Ascites + pericardial effusions
• Reduced foetal movements
• Hyperdynamic foetal circulation (increased velocities in the MCA or aorta on Doppler)
• Abnormal CTG with reduced variability, eventually a sinusoidal trace

Question 6

Investigations

Answer 6

Screened for anaemia at booking and at 28 weeks…

• FBC Haematinics / Iron Studies (see below)
• Blood film Haematocrit

Platelets

• Low platelets (usually < 100 x 109/L warrants further referral if in first trimester)
• De-novo immune thrombocytopaenia purpura (ITP)
  
  • Gestational thrombocytopaenia – more commonly detected > 28 weeks

NOTE: low MCV, MCH, MCHC = haematological conditions related to folate deficiency e.g. haemolytic anaemia, SCD, thalassaemia, hereditary spherocytosis

Question 7

Management

Answer 7

Supplements -> iron, B12 and folate (i.e. 100-200mg OD iron -> recheck in 2-3 weeks)

• I.E. Oral ferrous sulphate (note SEs: black stools, constipation, abdominal pain)
• I.E. Oral folic acid (if cause not known, don’t give this as can exacerbate B12 symptoms)
• I.E. IM hydroxycobalamin for B12 deficiency

Increased animal food in diet and advice

• Iron – green leafy vegetables, nuts, beans, seeds
• B12 – meat and dairy
• Folate – green leafy vegetables, nuts, yeast, liver

Intra-partum:

• Deliver in consultant-led unit
• IV access and group and screen on admission
• Active management of 3rd stage
• Active management of PPH
• Consider prophylactic syntocinon infusion

POSTNATAL PERIOD

• If Hb < 70g/L and where there is no threat or ongoing bleeding, then consideration of blood transfusion is done in an informed individual basis
• A cut-off of 100 g/L should be used in the postpartum period to determine if iron supplementation should be taken

Question 8

Complications

Answer 8

Iron supplementation- constipation

Low birthweight baby

Premature delivery

If Hb < 70g/L in labour or postpartum period, transfusion is indicated on an individual basis

Associated with postnatal depression

Reduced breast milk production

Results in 2-3% of post-partum haemorrage (PPH)