The purpose of this study is to evaluate the growth of the lung and how easily gas can be taken up by the lung in healthy infants born at full term without any breathing problems and infants born prematurely.

SPECIFIC AIM # 1: Determine the relationship between parenchymal tissue and alveolar volume with normal lung growth early in life We hypothesize that during the first two years of life that parenchymal surface area and alveolar volume increase with somatic growth; however, the ratio of surface area to volume remains constant, while ventilation within the lung becomes more homogenous.

SPECIFIC AIM # 2: Determine the pulmonary sequelae of premature birth and assess the effectiveness of early treatment strategies upon the pulmonary sequelae.

We hypothesize that premature birth impedes growth and development of the lung parenchyma and the airways at a corrected-age of 1-year. In addition, initiating continuous positive airway pressure (CPAP) and a permissive ventilatory strategy in very premature infants at birth will improve lung growth and lung function compared to treatment with early surfactant and conventional ventilation.

Inclusion Criteria:

• Group 1
• full term greater than 37 weeks
• Group 3
• infants born premature between 23-35 weeks of age to be tested between the ages of two to twenty four months corrected.

Exclusion Criteria:

• heart disease
• severe developmental delays

We are recruiting premature infants from Riley Hospial for Children, Methodist Hospital and IU NICu's. We also recruit from the Infant Lung Disease clinic at Riley Hospital for Children. Healhy full term infant are recruited through advertisements.