Abstract: 　Objective　To establish the reference range of reticulocyte hemoglobin content (Ret-He) in premature infants with different gestational ages (GA), and to evaluate the trend of change in Ret-He within 7 days after birth. Method　The RetHe values of premature infants with different gestational ages were measured at 24 hours, 2-3 days and 7 days after birth, and the correlation between Ret-He values and gestational age was analyzed. Results　A total of 1286 blood samples were collected from 699 premature infants. Gestational age was positively correlated with Ret-He levels at 24 hours (n=699, r=0.126, P=0.002), 2-3 days (n=440, r=0.487, P<0.001) and 7 days (n=147, r=0.510, P<0.001) after birth. The correlation was increased over the age. The average Ret-He levels of 147 premature infants at 24 hours, 2-3 days and 7 days after birth were 32.18, 27.82 and 28.85 pg respectively The Ret-He levels at 2-3 days after birth in preterm infants with different gestational ages were lower than those at 24 hours, and there was statistically difference (P<0.001). The Ret-He levels increased slightly from 2-3 days to 7 days after birth. The Ret-He levels at the 7th day after birth was higher than that at 2-3 days in preterm infants with gestational age of 30-33 weeks, and there was statistically difference (P<0.001). Conclusion　Ret-He was weakly correlated with gestational age and it is decreased significantly in 2-3 days after birth. The Ret-He level at 2-3 days after birth reflects the body's iron level more accurately.

Key words: premature infant;　reticulocyte hemoglobin content;　gestational age;　postnatal age