Thrombocytopenia in pregnancy.

Thrombocytopenia, classically defined as a platelet count of lower than 150,000/mL, has been observed in 7% to 10% of unselected pregnancies in the past 20 years because platelet counts are included with automated blood cell counters in routine prenatal screenings. Severe thrombocytopenia with a platelet count of lower than 50 x 10(9)/L is rare, occurring in less than 0.1% of pregnancies.