Abstract:

Objective To observe the trend of birth rate of late preterm infants, and explore the mother-related factors. Methods The annual birth rates of premature and late preterm infants born at Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine between 2001 and 2011 were analyzed with the method of epidemiological survey. Meanwhile, the data of infants who were born at this hospital in 2011 were collected, and all the late preterm infants （n=183） and term infants （n=2 144） were observed. The data of birth and prognosis in two groups were analyzed, and their mother-related factors were recorded for univariate and multivariate analysis. Results The epidemiological data revealed that the overall birth rate of late preterm infants born at this hospital between 2001 and 2011 was 5.47%, accounting for 67.39% of all the preterm infants. The annual birth rates of premature and late preterm infants were increasing yearly. There were significant differences in the birth weight, delivery mode, length of hospital stay and proportion of infants who were transferred into neonatal ward due to complications between late preterm and term infants (P<0.05 or P<0.01). For the infants who were transferred into neonatal ward, the prognosis of term infants was significantly better than that of late preterm infants (P<0.01). Univariate and multivariate analysis indicated that mother-related factors, including gestational hypertension, anemia, heart dysfunction, premature rupture of membranes, placenta previa, multiple pregnancy as well as smoking were independent risk factors of late preterm birth. Conclusion The incidence of late preterm infants increases yearly, and obstetricians should pay attention to the targeted intervention for mother-related factors.

Key words: late preterm infants, epidemiology, gestational diseases, social environment