Abstract: 　Objective　To investigate the causes and clinical characteristics of thrombocytopenia in very low birth weight infants. Methods　The clinical data of 51 very low birth weight infants with thrombocytopenia from January 2013 to December 2016 were retrospectively analyzed. Results　Among 51 cases, there were 31 males and 20 females, gestational age was 25+4 weeks to 36+1 weeks, the median birth weight was (1285±207.9) g, and the average onset age of thrombocytopenia was (11.84±13.16) days, delayed onsets were the most seen in 39 cases (76.5%). Infection accounted for 26 (66.7%) of 39 lateonset infants, and the causes of early-onset infants included asphyxia in 5 cases, pregnancy-induced hypertension in 4 cases, intrauterine growth retardation in 4 (1 had both pregnancy-induced hypertension and intrauterine growth retardation in the mother, and 1 had asphyxia, pregnancy-induced hypertension and intrauterine growth retardation in the mother). Among 51 cases, there were 31 (60.9%) had abnormal laboratory findings without bleeding (8 of early onset and 23 of late onset); 13 (25.4%) with intracranial hemorrhage (3 of early onset and 10 of late onset); 4 (7.8%) with pulmonary hemorrhage (1 of early onset and 3 of late onset); and 3 (5.9%) with cutaneous and mucosal hemorrhage (all of late onset). Forty-five (45, 88.2%) children had good prognosis and their platelets returned to normal after treatment; 10 infants with severe thrombocytopenia were given both intravenous administration of human immunoglobulin and etiological treatments, 3 patients with platelets < 30×109/L received platelets at the same time; 8 patients recovered and 2 patients gave up treatment; 5 children gave up treatment due to basic diseases (including 2 patients with severe thrombocytopenia). One case died of septic shock. Conclusion　Infection is the main cause of late-onset thrombocytopenia in very low birth weight infants, while placental dysfunction is the main cause of earlyonset of thrombocytopenia. Most of the symptoms are mild, and severe patients can also get well after treatment.

Key words: thrombocytopenia;　clinical analysisvery;　low birth weight infants