Abstract: Objective： To explore the variation tendency of different gestational weeks and types of prematurity and the relationship of preterm-related factors，mode of delivery，premature child birth weight and neonatal asphyxia. Methods：Retrospective analysis of 1 466 hospital delivery cases of preterm labor in the first Affiliated Hospital of Nanjing Medical University from January 2008 to December 2012. Statistical analysis of the tendency，the preterm-related factors，mode of delivery and the neonatal asphyxia of different gestational weeks of prematurity （early preterm，interim preterm，late preterm） and different types （spontaneous preterm birth，treatment of preterm labor）. Results：①From 2008 to 2012，the rate of preterm birth increased year by year（χ2=65.69，P＜0.001），while varying periods preterm showed an increasing trend，different types of preterm birth tended to increase. ②Varying periods of spontaneous preterm relevant factors include premature rupture of membranes，multiple pregnancy，abnormal fetal position，gestational diabetes some other unexplained factors and so on；the varying periods of therapeutic premature factors include gestational hypertension，placental factors，pregnancy complications，multiple pregnancy，intrahepatic cholestasis of pregnancy，fetal distress and so on. ③The vaginal delivery and cesarean section rate of different gestational weeks of preterm delivery was no significant difference （P＞0.05），while was statistically significant difference （P＜0.05） in different types of preterm delivery. The treatment of preterm cesarean section is higher than spontaneous preterm labor （P＜0.05）. ④The Birth weight and neonatal asphyxia varying different periods of preterm birth have been statistically significant（P＜0.05）, early preterm children with neonatal asphyxia （53.01%） higher than interim （33.46%，P＜0.05） and late preterm infants（28.61%，P＜0.05），no significant difference in interim and late preterm children（P＞0.05）. Conclusions：We should discriminate the preterm potential risk factors earlier and strengthen the perinatal management to reduce the incidence of preterm birth and improve the perinatal outcomes.

Key words: Premature birth, Natural childbirth, Cesarean section, Retrospective studies