Material and Method: The case-control study was conducted in three main tertiary hospitals in Kunming, China between September 2012 and July 2013. Children with first episode of wheezing diagnosed as bronchiolitis and tested for RSV were included. RSV was detected by real-time reverse transcription polymerase chain reaction. Mode of delivery and characteristics of children, parents, and household were interviewed and analyzed with RSV-positive status by multiple logistic regression.

Results: Of 265 children, RSV-positive was found in 75.5%, and the majority of children (83.3%) were younger than 12 months. Compared to vaginal delivery, the odds of RSV-positive detection were double in children born by elective cesarean delivery (adjusted odds ratio 2.32; 95% confidence interval 1.19-4.52). Children aged less than 6 months, born in the rainy season, having maternal history of asthma and living in family that smoked more than 20 cigarettes per day were more likely to be RSV-positive.

Conclusion: Children born by elective cesarean delivery increased the risk of RSV-positive acute bronchiolitis after adjusting for age, birth season, maternal asthma, and family smoking status.

Keywords: Acute bronchiolitis, Elective cesarean delivery, Predisposing factor, Respiratory syncytial virus