Effect of high versus low dose of human recombinant erythropoietin on the Anemia of prematurity

INTERVENTION: Group 1 received erythropoietin 500 unite/kg twice in week along with supplemental iron Group 2 received erythropoietin 500 unite/kg once in week along with supplemental iron Intervention 1: Group 1 received erythropoietin 500 unite/kg twice in week along with supplemental iron. Intervention 2: Group 2 received erythropoietin 500 unite/kg once in week along with supplemental iron. CONDITION: Anaemia of prematurity anemia of prematurity. ; Anaemia of prematurity PRIMARY OUTCOME: Hemotocrite and reticulocyte count. Timepoint: the beginning, third day and one week after the end of treatment. Method of measurement: venous sampling and laboratory measurement. INCLUSION CRITERIA: INCLUSION CRITERIA: Gestational age less than 34 weeks, breast milk feeding, hematocrit <30% when infant age is between 2 to 3 weeks or HCT<25% when infant age is more than 3 weeks. Exclusion criteria: Infants with hemolytic anemia, active bleeding or congenital malformation.