Thrombocytopenia is second to anemia as the most common hematologic abnormality encountered during pregnancy. Pregnancy is associated with numerous metabolic, immunologic, and other homeostatic changes that require careful consideration when attempting to define the cause of thrombocytopenia in a particular individual Thrombocytopenia is classically defined as a platelet count of less than 150,000/µL. Counts from 100,000 to 150,000/µL are considered mildly depressed, 50,000 to 100,000/µL are moderately depressed, and less than 50,000/µL are severely depressed. Pregnancy complicated with thrombocytopenia is a challenge to the clinician. The myriad of disease processes, either pregnancy-induced disorders or preconception medical conditions, can cloud the correct diagnosis. It is important to remember the great majority of patients will have a benign condition, but minorities of patients who have a more serious disease are at risk for serious morbidity and mortality. This descriptive cross-sectional hospital based study that aims to determine the prevalence of thrombocytopenia among pregnant women in Hail, KSA. And also to determine the correlation between thrombocytopenia and Haemoglobin concentration, MPV, Age, Number of Pregnancies and Gestational age. Simple random 100 pregnant in different gestational period participated in the study. In our study 11% show thrombocytopenia, 64% of them in the third trimester, and statistically no significant correlation between low platelets and low haemoglobin, also thrombocytopenia do not correlate to age or number of pregnancies but platelets count proportionate reversely with MPV .
