Cystic fibrosis (CF) is a life-shortening disease that causes breathing and digestive problems, but can now be diagnosed at the time of birth. Lung function is very hard to measure in infants, but growth is not. In this study the investigators aim to define growth in infants with CF in the first year of life with research quality precision and to understand factors that interfere with good growth.
Pancreatic enzyme replacement therapy (PERT) will be also be studied in a subgroup of infants. Two different doses of PERT will be evaluated for improving fat and nitrogen absorption in infants with CF.