My research involves measurement of the mechanical properties of the lungs, the behavior of lungs in response to mechanical ventilation, and the ability of the lungs to maintain oxygen and carbon dioxide levels in the blood. This is accomplished by means of measurements of the pressures required to ventilate the lungs and the breathing rate of ill infants; and the levels of oxygen and carbon dioxide in the arterial blood of critically ill infants. We are also studying the long term growth of premature twins and triplets. This involves annual visits to the neonatal Followup Clinic where height, weight, and head circumference are measured. Twins and triplets are compared with growth standards for single preterm infants, and multiples (twins and triplets) are compared with their siblings. The interest here is if and when preterm multiples "catch-up" with one another and with growth standards for singletons.