Table 1.

Summary of definitions and characteristics of neonatal respiratory conditions

Condition	Term or preterm status	Definition and etiology	Clinical characteristics	Radiographic characteristics	Risk factors
Respiratory Distress Syndrome (RDS) [7, 10, 12, 14]	Preterm	Respiratory distress caused by surfactant deficiency or dysfunction from immature lung development	Tachypnea, grunting, retractions, and cyanosis	Poorly inflated lungs and ground-glass appearance with air bronchograms	Prematurity, male sex, white race, and/or maternal diabetes
Apnoea of Prematurity (AOP) [9, 12]	Preterm	A self-limiting disorder with pauses in breathing caused by immature development of the lungs and brain (central), lung obstruction (obstructive), or both (mixed). May also be considered a symptom of other conditions, such as low blood sugar or infection	Cessation of breathing for more than 20 s, bradycardia, cyanosis, and/or pallor	Radiograph not necessary	Prematurity and genetic susceptibility
Bronchopulmonary Dysplasia (BPD) [8, 10, 12, 13]	Preterm	Also known as a type of chronic lung disease resulting in oxygen dependency for at least 28 days and may persist by 36 weeks postmenstrual age caused by immature, damaged lungs previously exposed to invasive treatment(s)	Apnoea, tachypnea, grunting, retractions, and/or wheezing	Pulmonary fibrosis, hyperinflated lungs with larger alveoli and smaller surface area, and reticular markings	Prematurity, mechanical ventilation, chorioamnionitis, postnatal sepsis, oxygen toxicity, fluid overload, and/or patent ductus arteriosus
Meconium Aspiration Syndrome (MAS) [3, 4, 10, 12]	Late preterm to post-term	Lung obstruction, inflammation, irritation, infection, and/or surfactant deactivation caused by inhaled meconium	Tachypnea, grunting, retractions, and/or cyanosis	Hyperinflated lungs with patchy densities	Meconium-stained amniotic fluid, post-term birth, small for gestation age, fetal distress, placental issues, and/or umbilical cord problems
Transient Tachypnea of the Newborn (TTN) [4, 6, 10–12]	Any	A self-limiting disorder with persistent alveolar fluid caused by delayed or inadequate reabsorption and/or pulmonary maladaptation	Tachypnea, hypoxemia, acidosis, and cyanosis	Lung hyper-expansion, perihilar markings with fissure fluid, or pleural effusions	Caesarean delivery, maternal asthma, male sex, macrosomia, and/or maternal diabetes