To investigate the relationship between bronchopulmonary dysplasia and thrombocytopenia.

A prosepective case-control study ,the case were matched with 1:1according to gestational age,birth weight and admission diagnosis and divided into two groups according to the consensus definition of National Institute of Child Health and Human Development (NICHD). Platelet count, circulating megakaryocyte count, platelet activating markers (CD62P and CD63), thrombopoietin were recorded and compared in two groups, then, serial thrombopoietin levels and concomitant platelet counts were measured in infants with BPD.

Inclusion Criteria:

1. presence of clinical and radiologic signs of BPD, according to conventional criteria (Greenough, 1992);
2. presence of peripheral arterial catheter;
3. gestation <32 weeks;
4. birth weight <1.5 kg;
5. requiring mechanical ventilation for the treatment of respiratory distress syndrome for at least 3 days during the first weeks of life;
6. ventilator and/or oxygen dependent at time of enrolment;

Exclusion Criteria:

1. congenital abnormalities;
2. infection (bacteria infection confirmed by positive blood culture or viral infection confirmed by serological test or viral culture)
3. evidence of complications of perinatal asphyxia including an apgar score <3 at one or five minute after birth, evidence of hypoxic-ischemic encephalopathy, acute tubular necrosis, or transient myocardial ischemia;
4. identifiable hematologic disease;

Bronchopulmonary dysplasia (BPD) is one of the common complications in neonatal intensive care units (NICU), mainly occurs in premature infants and is considered to be the main cause of premature death