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Key messages

  • Although mild thrombocytopenia (TP) is common, most infants do not require treatment.
  • TP in newborns is defined as a platelet count less than 150 x 109/L. This occurs in 1-4 per cent of all newborn babies.
  • The majority of episodes of TP present during the first 72 hours of life.
  • The highest incidence of TP is in sick, preterm babies (40-70 per cent).
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    In June 2023, we commenced a project to review and update the Maternity and Neonatal eHandbook guidelines with a view to completion in 2024. Please be aware that pending this review, some of the current guidelines may be out of date. In the meantime, we recommend that you also refer to more contemporaneous evidence.

    A well infant who presents unexpectedly on the first day of life with extensive bruising and/or a petechial rash and who is found to have isolated thrombocytopenia (platelet count <100 x 109/L) without an obvious cause must be presumed to have neonatal alloimmune thrombocytopenia until proven otherwise.

    Thrombocytopenia (TP) in the newborn is defined as a platelet count less than 150 x 109/L. This occurs in 1-4 per cent of all newborn babies.

    Points to note about thrombocytopenia:

    • The majority of episodes of TP present during the first 72 hours of life.
    • The highest incidence of TP is in sick, preterm babies (40-70 per cent).
    • Thrombocytopenia is the most common haematological abnormality in the NICU. Nearly 25 per cent of sick infants develop TP, which is trivial for some infants with a platelet count of 100-150 x 109/L.
    • 50 per cent or more of affected infants, platelet counts fall below 100 x 109/L.
    • 20 per cent of infants have platelet counts < 50 x 109/L.
    • Automated platelet counts may be abnormally low due to platelet aggregation in the sample.
    • Confirm low results by blood film examination and often a repeat sample (arterial or venous) is needed.

    Because the most likely cause of severe TP in a baby remaining in a special care nursery (SCN) is neonatal alloimmune thrombocytopenia (NAITP), special attention is given to this condition.

    NAIT is often referred to as fetomaternal alloimmune thrombocytopenia (FMAIT).

    Differential diagnosis of thrombocytopenia in babies by age at presentation


    • neonatal alloimmune TP (NAITP)
    • maternal autoimmune disease idiopathic thrombocytopenia purpura (ITP), SLE
    • congenital infections CMVtoxoplasmosisrubella
    • severe rhesus disease
    • chromosomal disorders trisomy 21, 18, 13
    • rare inherited disorders TAR - TP with absent radii

    Neonate < 72 hours of age

    • placental insufficiency PET, IUGR, diabetes
    • birth asphyxia
    • perinatal infection GBS, E. coli, haemophilus influenza listeria
    • congenital infection CMVtoxoplasmosisrubella
    • NAITP
    • maternal autoimmune disease ITP, SLE
    • thrombosis renal vein, aortic
    • rare inherited disorders TAR, Wiskott-Aldrich syndrome, congenital amegakaryocytic thrombocytopenia (CAMT)

    Neonate > 72 hours of age

    • bacterial infection (nosocomial)
    • infected indwelling lines
    • NEC
    • maternal autoimmune disorders ITP, SLE
    • congenital infection CMV, toxoplasmosis, rubella
    • rare inherited disorders TAR, Wiskott-Aldrich syndrome

    Neonatal alloimmune thrombocytopenia (NAITP)

    Issues to note about NAITP:

    • NAITP is sometimes known as isoimmune thrombocytopenia and results from sensitisation of the mother to antigens present on fetal platelets.
    • In contrast to Rh alloimmunisation, 40-60 per cent cases occur in a first born.
    • 75-90% of subsequent pregnancies are affected.
    • Severe cases in fetus or newborn occur in one in 1,200 pregnancies.
    • If NAITP is untreated, intracranial haemorrhage occurs in 10-30 per cent of cases.
    • Overall fetal and neonatal mortality in 6-13 per cent of cases.
    • Long-term neurodevelopmental sequelae in 20-25 per cent of survivors.
    • Diagnosed by demonstration of fetomaternal incompatibility for a platelet surface antigen and presence of maternal platelet alloantibodies that react with a 'foreign' antigen present on platelets of the infant and father but not the mother's platelets.
    • Suspect NAIT in a thrombocytopenic newborn that is otherwise well, normal maternal platelets and no history of maternal autoimmune disease.
    • All children with suspected or proven NAITP warrant a cranial ultrasound to exclude intracranial haemorrhage.

    Platelet function impairment

    Platelet function (but not absolute count) may be impaired with:

    • maternal aspirin not usually severe
    • indomethacin
    • infant of diabetic mothers possibility of enhanced platelet reactivity
    • rarely inherited platelet function defect.

    Management of thrombocytopenia

    Risk of bleeding

    The risk of bleeding is increased where there is:

    • decreased production rather than increased destruction
    • platelet function defect plus thrombocytopenia
    • the platelet count < 50 x 109/L.

    Platelet transfusion

    There is no accepted 'safe' level of platelets in neonates.

    Platelet transfusions need to be considered for each individual based on:

    • the platelet count
    • clinical circumstances
    • the presence or absence of bleeding treat the underlying cause if possible
    • potential triggers for platelet transfusion (see Table 1).

    Table 1

    Normal platelet count Platelet dysfunction and clinical
    Platelet count < 100 Major bleeding
    DIC and bleeding
    Sepsis with rapid deterioration
    Platelet count < 50 Minor bleeding
    Exchange transfusion
    Platelet count < 30 Asymptomatic term infant

    The recommended volume of platelets to be transfused is 10-20 mL/kg.

    • This should transiently increase the platelet count by 50-100 x 109/L. Transfuse over 30 minutes and monitor platelet count one hour post transfusion.
    • Ensure that the platelets are:
      • leukocyte-depleted
      • CMV-negative (if unknown, filtering may be required before transfusion)
      • where possible, ABO compatible plasma
      • irradiated if infant is immunocompromised.

    Specific treatment required for NAITP

    Issues to note about treatment for NAITP:

    • Use washed, irradiated maternal platelets (certain compatibility, availability, safety) or antigen-compatible donor platelets.
    • It has been shown that administration of IVIG before birth results in increasing fetal platelet counts and may help reduce thrombocytopenia in cases of NAIT.
    • Caesarean section is recommended to prevent intracranial haemorrhage.
    • Random platelets in emergency situations are often the only available therapy in the initial instance as delays to platelet transfusion should be avoided.
    • Platelet increment can be improved by giving IVIG 1 g/kg immediately prior to platelet transfusion.
    • High dose intravenous IgG may be effective in the absence of/in addition to maternal platelets, 1 g/kg for two days.

    Areas of uncertainty in clinical practice

    Areas of uncertainty:

    • A 'safe' platelet count for newborn infants has not yet been identified.
    • Evidence-based guidelines for platelet transfusion therapy are yet to be defined.
    • There is little evidence that steroids and exchange transfusion have a therapeutic role in NAITP.

    More information


    • Chakravorty S, Murray N, Roberts I. Neonatal Thrombocytopenia Early Human Development 2005; 81:35-41
    • Roberts IAG, Murray NA. Review. Management of thrombocytopenia in neonates. Br J Haematol 1999; 105:864-70
    • Blanchette VC, Johnson J, Rand M. The management of alloimmune neonatal thrombocytopenia. Bailliere's Clinical Haematology 2000;13:365-90
    • Letsky EA, Greaves M. Guideline. Guidelines on the investigation and management of thrombocytopenia in pregnancy and neonatal alloimmune thrombocytopenia. Br J Haematol 1996;95:21-26
    • Roberts AG, Murray NA. Neonatal thrombocytopenia: new insights into pathogenesis and implications for clinical management.
    • Current Opinion in Pediatrics. 2001;13:16-21
    • Rayment R, Brunskill SJ, Stanworth S, Soothill PW, Roberts DJ, Murphy MF. Antenatal interventions for fetomaternal alloimmune thrombocytopenia. Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD004226. DOI: 10.1002/14651858.CD004226.pub2
    • Bassler D, Greinacher A, Okascharoen C, Klenner A, Ditomasso J, Kiefel V, Chan A, Paes B.A systematic review and survey of the management of unexpected neonatal alloimmune thrombocytopenia.Transfusion. 2008 Jan;48(1):92-8. Epub 2007 Sep 24

    Get in touch

    Clinical Guidance Team
    Safer Care Victoria

    Version history

    First published: September 2013
    Review by: September 2016

    Uncontrolled when downloaded
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