All children that are born before the 35th week after fertilization (37th WoP after the LMP) are considered to be premature deliveries. These children come into the world with still immature organ systems and functions. These can lead to a postpartum series of acute diseases and ensuing chronic pulmonary and neurological damage.
The survival chances of a premature baby with a weight at birth of less than 1500 gm has improved significantly in the last decade. Today it is assumed that more than 50% of those born prematurely with a weight at birth between 600-1000 gm and more as well as 85% of all premature babies with a weight at birth between 1000-1499 gm survive.
One distinguishes between eutrophic and hypotrophic premature babies. For this classification growth and weight curves are applied that, with the help of measurements made available in the respective population groups, display statistically their normal distributions.