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Causes of neonatal thrombocytopenia

Caraciolo J Fernandes, MD
Section Editors
Joseph A Garcia-Prats, MD
Donald H Mahoney, Jr, MD
Deputy Editor
Melanie S Kim, MD


Although thrombocytopenia is relatively rare in the general newborn population, it occurs more frequently in patients admitted to neonatal intensive care units (NICUs). The two main underlying pathologic mechanisms are increased destruction or decreased production. Severe neonatal thrombocytopenia (platelet count <50,000/microL) is associated with bleeding and, potentially, significant morbidity, although there is a poor correlation between platelet count and incidence of bleeding. As a result, it is important to identify at-risk infants, and if needed, initiate therapy to prevent associated complications.

The incidence and more common causes of thrombocytopenia in the newborn are reviewed here. The evaluation and general management of neonatal thrombocytopenia are discussed separately. (See "Clinical manifestations, evaluation, and management of neonatal thrombocytopenia".)


Neonatal thrombocytopenia is typically defined as a platelet count less than 150,000/microL based upon the definition used in adults, which corresponds to values at or below the 5th percentile. Degrees of thrombocytopenia can be further subdivided into mild (platelet count 100,000 to 150,000/microL), moderate (50,000 to 99,000/microL), and severe (<50,000/microL).

However, healthy preterm and term newborns can have platelet counts below the defined normal platelet count [1-3]. This was best illustrated in a study from the Intermountain Healthcare group that reviewed the platelet counts of 34,146 neonates (gestational age [GA] from 22 to 42 weeks) during the first three days of life [2]. In neonates, the 5th percentile was lower than the standard adult value of 150,000/microL and decreased with decreasing GA. For example, the 5th percentile was 104,200/microL for infants below 32 weeks gestation, and was 123,100/microL for late preterm (34 to 36 weeks gestation) and term (GA greater than 37 weeks) infants. Platelet counts increased with advancing postnatal age.

In another report from the Intermountain Healthcare group, the incidence of thrombocytopenia (defined as platelet count <150,000/microL) was 31 percent for small for gestational age (SGA) infants (birth weight [BW] <10th percentile for GA) [4]. Ten percent of the infants with thrombocytopenia (3.5 percent of the entire SGA cohort) had a recognized cause of thrombocytopenia (disseminated intravascular coagulation, early-onset sepsis, or extracorporeal membrane oxygenation [ECMO]), which was associated with a high mortality rate (65 percent). The remaining majority did not have an obvious underlying etiology and had a low mortality rate (2 percent) with a mean nadir count of 93,000/microL at day 4 of life.

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Literature review current through: Nov 2017. | This topic last updated: Nov 28, 2017.
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