There are more and more late preterm infants in recent years. Due to the immature physiological and metabolic functions, late preterm neonates are more prone to various short- and long-term respiratory complications in their early postnatal period, such as neonatal respiratory distress syndrome, wet lung and apnea in the short term, and asthma and respiratory syncytial virus infection in the long term, which significantly increase the admission and fatality rate of late preterm infants in their infancy and school age compared with the full-term ones. Clinicians should be much aware of the short- and long-term respiratory complications in late preterm infants so as to promote clinical management and improve the long-term quality of lives of these infants.

Objective To study the difference of clinical outcome between late preterm twins (LPT) and late preterm singletons (LPS),and the influence of assisted reproduction technology (ART) or natural conception on the clinical outcomes of LPT.Method The data of late preterm infants born in the Beijing Obstetrics and Gynecology Hospital between January 2016 and January 2018 were retrospectively collected.Infants were assigned to LPT group or LPS group according to twins or singleton status.The differences of the demographic data,morbidity,oxygen therapy rate,respiratory support rate,mortality,hospitalization rate and hospitalization time between LPT and LPS were compared.In order to analyze the effects of different ways of conception on LPT,LPT was further divided into assisted reproduction technology (ART) subgroup and natural pregnancy subgroup.Result A total of 1 824 late preterm infants were included in the study,including 582 cases of LPT and 1 242 cases of LPS.The birth weight and body length of LPT were lower than those ofLPS [(2572±395)gvs.(2614±413)g,P＜0.05;(46.5±1.1)cm vs.(47.5 ± 1.0)cm,P ＜0.01],while the cesarean delivery rate of LPT was higher than that of LPS [90.7％ (528/582) vs.39.9％ (496/1 242),P ＜ 0.01].The incidence of respiratory distress syndrome (RDS) in LPT was higher than that of LPS [5.2％ (30/582) vs.3.6％ (45/1 242),P ＜ 0.05],and the length of hospitalization of LPT was also longer than that of LPS[(8.9 ±3.1)d vs.(7.2 ±2.9)d,P ＜0.01],the differences were statistically significant.There were no significant differences between groups in neonatal pneumonia,apnea,hypoglycemia,sepsis,neonatal necrotizing enterocolitis (NEC),grade Ⅲ ～ Ⅳ intracranial hemorrhage,severe asphyxia,bronchopulmonary dysplasia (BPD),oxygen therapy rate,respiratory support rate and mortality rate.There was also no significant difference between ART subgroup and natural pregnancy subgroup in gestational age,gender,cesarean section rate,birth weight,and birth length (P ＞ 0.05).There was no significant difference in RDS,pneumonia,apnea,hypoglycemia,sepsis,NEC,Ⅲ ～ Ⅳ intracranial hemorrhage,severe asphyxia,BPD,oxygen uptake rate,respiratory support rate,mortality rate and hospitalization time between the two subgroups (P ＞ 0.05).Conclusion The birth weight and birth length of LPT are lower than those of LPS,and the incidence of RDS is higher.The hospitalization time of LPT is also longer than that of LPS.It is necessary to strengthen the high-risk management of twin pregnant women and post-natal management of LPT.

Objective To evaluate the effects of gestational diabetes mellitus (GDM) and its treatment during pregnancy on neonatal respiratory diseases in late-preterm infants.Method From January 2013 to December 2016,respiratory outcome of singleton infants (gestational age:34-36 weeks) of GDM mothers(GDM group) was compared with infants delivered from mothers without GDM(non-GDM group).We also studied the relationship between maternal GDM treatment (insulin-treated GDM and diet-controlled GDM) and neonatal respiratory outcome,including incidences of respiratory diseases,mechical ventilation and oxygen supplementation.Result A total of 2 174 late-preterm infants were enrolled in this study,including 425 in GDM group and 1 749 non-GDM group.The average birth weight was (2 688 ± 423) g,ranging from 1 320 g to 4 275 g,and mean gestational age was (35.5 ± 0.7) weeks.Comparing with nonGDM group,the incidence of cesarean delivery was significantly higher in GDM group (35.5％ vs.30.5％,P ＜0.05),so was the incidence of antenatal corticosteroids (19.1％ vs.13.0％,P ＜0.01).GDM group was more likely to develop wet lung comparing with non-GDM group (8.0％ vs.5.4％,P ＜ 0.05).A similar incidence of neonatal respiratory distress syndrome (RDS),apnea,pneumonia,pneumothorax and pulmonary hypertension were found in the two groups (P ＞0.05).In the GDM group,a total of 91 infants were born to mothers with insulin-treated GDM and 334 diet-controlled GDM.Comparing with the diet controlled group,insulin treatment group was associated with higher risk of neonatal RDS (6.6％ vs.1.8％,P ＜ 0.05) and higher incidence of mechanical ventilation (13.2％ vs.6.0％,P ＜ 0.05).A similar incidences of wet lung,apnea,pneumonia,pneumothorax and pulmonary hypertension were found in the two groups (P ＞ 0.05).Conclusion The late-preterm infants born to GDM mothers with insulin treatment have higher incidences of neonatal RDS and mechanical ventilation,and they need much more care.