目的 观察晚期早产儿的发生率和变化趋势，并分析其母源性影响因素。方法 采用流行病学调查方法，分析2001—2011年上海交通大学医学院附属新华医院产科所有早产儿和晚期早产儿的发生率。同时，收集该院2011年出生的新生儿，将晚期早产儿（n=183）和足月儿（n=2 144）作为观察对象，分析两组新生儿的出生情况及预后指标，并对母源性指标进行单因素和多因素分析。结果 流行病学资料显示，2001—2011年该院产科晚期早产儿总发生率为5.47%，占早产儿总数的67.39%；每年的早产儿、晚期早产儿发生率基本呈逐年上升趋势。晚期早产儿组与足月儿组的出生体质量、出生方式、住院时间及出生后因并发症转入新生儿科的比例差异均有统计学意义（P<0.05或P<0.01）；对于两组中转入新生儿病区的患儿，足月儿组的预后明显优于晚期早产儿组（P<0.01）。单因素和多因素分析显示：母亲有妊娠期高血压疾病、贫血、心功能异常、胎膜早破、前置胎盘、多胎妊娠及吸烟为晚期早产的独立危险因素。结论 晚期早产儿发生率呈上升趋势，产科医师应对母源性危险因素进行针对性干预。

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.