Factors Affecting Lung Function in Preschool Children with a History of Transient Tachypnea of the Newborn

Background: Transient tachypnea of the newborn (TTN) is a common cause of self-limiting respiratory distress in neonates. Increasing data suggest that TTN may be a risk factor for developing childhood wheezing attacks or asthma. Objectives: The aim was to evaluate lung functions in preschool children diagnosed with TTN in the neonatal period using an Impulse Oscillometry System (IOS) to assess the presence of respiratory morbidity and its contributing factors. Methods: In this prospective study, preschool children diagnosed with TTN in the neonatal period and healthy age-matched children were defined as the TTN group and control group, respectively. Impulse Oscillometry System values for resistance (R5- R20), reactance (X5-X20), resonant frequency (Z5), and reactance area (AX) were compared between both groups and within the TTN subgroups. Asthma diagnosis was determined following IOS testing using the Modified Asthma Predictive Index/ International Study of Asthma and Allergies in Childhood (ISAAC). Results: A total of 52 preschool children and 101 healthy controls participated in the study. R5 minus R20 was significantly higher, and X10 and X15 values were significantly lower in the TTN group compared to the controls. Additionally, higher Rvalues and AX values were observed in TTN subgroups with a history of late preterm birth, noninvasive respiratory support, and maternal asthma. The rates of variable respiratory symptoms and >= 4 wheezing attacks in one year were 20.5% and 18%, respectively. By the end of the study, the rate of newly diagnosed asthma in the TTN group was 30.8%. Moreover, Rvalues and Z5 were significantly higher, and X values were significantly lower in the TTN subgroup exposed to passive smoking (PS) compared to the TTN subgroup not exposed. Conclusions: Our study showed that preschool children diagnosed with TTN in the neonatal period may have peripheral airway obstruction, a known characteristic of asthma. In addition to TTN-related factors, exposure to cigarette smoke appears to negatively impact their lung function. These findings suggest that long-term medical care should be provided for these children.