目的：探讨晚期早产儿呼吸系统疾病患病的临床特点。方法：选取2009年1月至2010年12月在我院产科出生的新生儿，其中晚期早产儿 (胎龄34~36+6周)630例，足月儿4401例，早期早产儿（胎龄≤33+6周）328例。其中患呼吸系统疾病者包括晚期早产儿84例，足月儿135例，早期早产儿182例。比较3组新生儿呼吸系统疾病发病情况、临床特点及危重程度。结果：（1）晚期早产儿组呼吸系统疾病发生率、病死率及危重症比例均高于足月儿组，而低于早期早产儿组(P<0.01)。（2）晚期早产儿组呼吸困难起病时间早于足月儿组，晚于早期早产儿组（P<0.01）；呼吸增快百分比较其他两组高，而三凹征百分比较低(P<0.05)； 晚期早产儿组需氧疗及机械通气的比例均明显高于足月儿组，而低于早期早产儿组(P<0.05)。（3）多元线性回归分析发现血氧分压降低、红细胞压积减低、血pH值减低、呼吸减慢、动脉血氧饱和度减低、动脉收缩压减低、5 min Apgar评分减低、胎龄较小、血尿素氮增高、心率增快、呼吸增快是新生儿呼吸系统疾病危重症的影响因素。结论：晚期早产儿比足月儿更容易出现呼吸系统疾病，危重程度较重，需加强呼吸支持。晚期早产儿呼吸困难多表现为呼吸增快，起病时间早于足月儿而晚于早期早产儿。对于晚期早产儿，如发现呼吸困难、心率、血压异常及多系统受累表现，常提示其病情危重，应积极治疗。

OBJECTIVE: To evaluate the clinical features of respiratory diseases of late preterm neonates. METHODS: Six hundred and thirty late preterm infant(gestational age: 34~36+6weeks)，4401 cases of term infants and 328 early preterm infants who were born at the obstetrical department of Peking University 3rd Hospital from January 2009 to December 2010 were enrolled. Among them 84 late preterm infants, 135 term infants and 182 early preterm infants developed respiratory diseases. The incidence of respiratory diseases，clinical features and the severity of the diseases were compared among the three groups. RESULTS: The incidence and mortality rates of respiratory diseases and the percentage of severe cases were significantly higher in the late preterm group than in the term group, but lower than in the early preterm group (P<0.01). The symptoms of respiratory disease occurred earlier in the late preterm group than in the term group, but later than in the early preterm group (P<0.01). The late preterm group had a significantly higher incidence of tachypnea and lower incidence of retraction sign when compared with the term and early preterm groups (P<0.05). The percentages requiring oxygen therapy and mechanical ventilation in the late preterm group were both significantly higher than in the term group, but lower than in the early preterm group (P<0.05). The multiple linear regression analysis showed 11 factors associated with the severity of respiratory diseases: decreased arterial partial pressure of oxygen, hematokrit, pH value and respiratory rate, arterial oxyhemoglobin saturation, systolic arterial pressure, 5 minute Apgar score and gestational age, and increased blood urea nitrogen, heart rate and respiratory rate. CONCLUSIONS: Late preterm infants are more likely to develop respiratory diseases than term infants, and to develop a more severe condition and need a more intensive respiratory support treatment. Tachypnea is a common presentation of dyspnea in late preterm infants and occurs earlier than in term infants but later than in early preterm infants. It may usually indicate a serious condition when dyspnea, abnormal heart rate and blood pressure, and multisystem damages occur in late preterm infants.