Preterm infants are often<unk>  and typically experience heavy blood losses from frequent laboratory testing in the first few weeks of life. Although their<unk>  is multifactorial, repeated blood sampling and reduced erythropoiesis with extremely low serum levels of erythropoietin (EPO) are major causative factors. Blood sampling done for laboratory testing can easily remove enough blood to produce<unk> . Obladen, Sachsenweger and Stahnke (1987) studied 60 very low birth weight infants during the first 28 days of life. Infants were divided into 3 groups, group 1 (no ventilator support, 24 ml/kg blood loss), group 2(minor ventilated support, 60 ml/kg blood loss), and group 3(ventilated support for respiratory distress syndrome, 67 ml/kg blood loss). Infants were checked for clinical symptoms and laboratory signs of<unk>  24 hours before and after the blood transfusion. The study found that groups 2 and 3 who had significant amount of blood loss, showed poor weight gain, pallor and distended abdomen. These reactions are the most frequent symptoms of<unk>  in very low birth weight infants. During the first weeks of life, all infants experience a decline in circulating red blood cell (RBC) volume generally expressed as blood hemoglobin concentration (Hb). As<unk>  develops, there is even more of a significant reduction in the concentration of hemoglobin. Normally this stimulates a significant increased production of erythropoietin (EPO), but this response is diminished in premature infants. Dear, Gill, Newell, Richards and Schwarz (2005) conducted a study to show that there is a weak negative correlation between EPO and Hb. The researchers recruited 39 preterm infants from 10 days of age or as soon as they could manage without respiratory support. They estimated total EPO and Hb weekly and 2 days after a blood transfusion. The study found that when Hb>10, EPO mean was 20.6 and when Hb≤10, EPO mean was 26.8. As Hb goes down, EPO goes up. While the reason for this decreased response is not fully understood, Strauss (n.d.) states that it results from both physiological factors (e.g., the rapid rate of growth and need for a commensurate increase in RBC mass to accompany the increase in blood volume) and, in sick premature infants, from phlebotomy blood losses. In premature infants this decline occurs earlier and more pronounced that it does in healthy term infants. Healthy term infants Hb rarely falls below 9 g/dL at an age of approximately 10–12 weeks, while in premature infants, even in those without complicating illnesses, the mean Hb falls to approximately 8g/dL in infants of 1.0-1.5 kg birth weight and to 7g/dL in infants <1.0 kg. Because this postnatal drop in hemoglobin level is universal and is well tolerated in term infants, it is commonly referred to as the “physiologic”<unk>  of infancy. However, in premature infants the decline in Hb may be associated with abnormal clinical signs severe enough to prompt transfusions.
Anemia of prematurity
Hemolytic disease of the newborn 
Hemolytic disease of the newborn
Neonatal sepsis
Neonatal meningitis
Shaken baby syndrome
Neonatal hypocalcemia
Neonatal diabetes