To investigate the incidence of hyperbilirubinemia in late preterm newborns and their perinatal management.

From October 2013 to March 2015, a total of 35 cases of late preterm newborns who were diagnosed as hyperbilirubinemia were selected from 276 inpatient of late preterm newborns in Department of Neonatology, West China Second University Hospital, Sichuan University were included in study group, and another 35 patients who had not been diagnosed as hyperbilirubinemia were selected randomly from the other 241 inpatient cases and were included in control group by isometric sampling method. Retrospective analysis method was used to collect the clinical data of two groups and to analyze the following items. ①To compare the constituent ratios of gender, gestational age at birth, day age at the time of admission, admission ways, appropriate for gestational age (AGA) infants, small for gestational age (SGA) infants, large for gestational age (LGA) infants, delivery modes, and the incidences of premature rupture of membrane, intrauterine or postnatal asphyxia, cephalohematoma, pregnancy diseases in pregnant women between study group and control group by chi-square method or Fisher exact probability method. ②Incidence of hyperbilirubinemia among 276 cases of late preterm newborns in the study, and the relationship with the gender were analyzed. ③The constituent ratios of gender, day age at the time of admission, admission ways, gestational age at birth, AGA or LGA infants, delivery modes, birth institutions, and the incidences of severe and extremely severe highperbilirubinemia, concomitant diseases or causes of disease, bilirubin encephalopathy and readmission etc. in study group were analyzed.

①There were significant differences between two groups among the constituent ratios of gestational age at birth, day age at the time of admission, admission ways, premature types, delivery modes, and the incidences of premature rupture of membranes and intrauterine or postnatal asphyxia (χ²=12.011, P=0.002; χ²=16.931, P<0.001; χ²=31.895, P<0.001; χ²=13.473, P=0.001; χ²=18.913, P<0.001; χ²=5.927, P=0.019; χ²=8.454, P=0.004), respectively. There were no significant differences between two groups among the gender ratio, the incidences of cephalohematoma in fetuses and pregnancy diseases in pregnant women (P>0.05), respectively. ②Among the 276 cases of late preterm newborns included in the study, hyperbilirubinemia incidence was 12.7% (35/276). Gender ratio of male and female was 1.9∶1 in 35 cases of late preterm newborns diagnosed as hyperbilirubinemia. ③Among the 35 hyperbilirubinemia of late preterm newborns in study group, the gestational age at birth was 34^{+ 0}-36^{+ 6} weeks, severe and extremely severe hyperbilirubinemia both were 15 cases, which accounting for 85.7% (30/35), there was none of dangerous hyperbilirubinemia neonates. And hyperbilirubinemia of late preterm newborns whose age≤7 d was more than that of age>7 d at the time of admission, and the proportion of late preterm newborns of age≤7 d was 60.0% (21/35), after discharge from rooming-in periods, they rehospitalized from outpatient and emergency department into neonatal department, and their rehospitalized rate was 94.3% (33/35). Level of birth medical institutions of late preterm newborns in study group between grade second and grade third was 45.7% (16/35) and 48.6% (17/35), respectively. Among the accompanied diseases or causes of 35 hyperbilirubinemia of late preterm newborns in study group, infection, ABO blood group incompatible hemolytic disease, glucose-6-phosphate dehydrogenase (G6PD) deficiency, cephalohematoma and multiple causes of diseases accounted for 17.1% (6/35), 11.4% (4/35), 5.7% (2/35), 2.9% (1/35), 5.7%(2/35), respectively; but there was the other 57.1% (20/35) still could not found a clear cause of hyperbilirubinemia. The incidence of bilirubin encephalopathy of late preterm newborns in study group was as high as 40% (14/35), and blood exchange rate was also as high as 62.9% (22/35).

In late preterm newborns with hyperbilirubinemia, the rate of severe and extremely severe hyperbilirubinemia, and incidence of bilirubin encephalopathy are high. And the rates of males, age≤7 d at the time of admission, 35^{+ 0}-35^{+ 6} gestational weeks at birth, AGA infants, natural birth, complications were also high. Therefore, it is important to emphasize the training of health care workers for normative management of neonatal hyperbilirubinemia, and strengthening neonatal icterus monitoring perinatal management and other measures, so as to reduce disability and improve the life quality of late preterm newborns with hyperbilirubinemia.