Figure 2From: Prematurity and respiratory outcomes program (PROP): study protocol of a prospective multicenter study of respiratory outcomes of preterm infants in the United StatesPROP Study Protocol Time Line spans from birth to one year of corrected age collecting health data and biospecimens. *Tracheal aspirate samples were collected if the infant was intubated and clinically required suctioning. #Physiologic challenge testing was either from oxygen to room air (21% oxygen, the “Room Air Challenge”) or from room air to 15% oxygen (“hypoxia challenge”) depending on status. NIRA: Non-invasive respiratory assessment; GERD: gastroesophageal reflux disease; iPFT: infant pulmonary function testing.Back to article page