Background and Aims: Human milk offers many advantages for the premature infant, but the content of macro-nutrients might be inadequate. Fortification of mothers own milk or premature formula have shown to improve growth among premature infants while they are hospitalized. It might be beneficial to continue with fortification or premature formula after hospital discharge. The aim of the study is to describe breast-feeding rate at discharge among very preterm infants, whether it is possible to supply breastfeeding with fortification after discharge, eating habits after discharge, growth-velocity and registration of allergic symptoms within the first year of life among premature infants. Methods: The study is a randomized controlled study where premature infants born with a gestational age (GA) ≤ 32+0 weeks are fed premature formula or (if the mother is breastfeeding) randomized to either breastfeeding in combination with fortifier or breastfeeding without fortifier until the corrected age of 4 months. The infants will be followed in the ph.d.-research period until the corrected age of 1 year (planning follow-up until 5-6 years). Four pediatric departments (Odense, Kolding, Skejby and Holbæk) are part of the project. Inclusion started in august 2004 and will end by September 1. 2008. Results until august 2008: A total of 588 premature infants with GA ≤ 32+0 have been registered so far. One hundred and thirty six (23%) have been excluded because of severe illness or death and 148 (26%) did not want to or were not asked to participate (not active group). The remaining 297 (51%) healthy premature infants are participating in the randomized controlled study (active group). Twins or triplets represent 26% of the population. Infants born small for gestational age (SGA) defined as z-score below -2SD (Marsal 1996) represent 37% of the population. The breastfeeding rate at discharge (GA 34.-37. weeks corrected age (CA)) within "the active group" is 62% and the bottle feeding rate is 38%. The breastfeeding rate in the "not active group" is 52% and the bottle feeding rate is 49% (p=0,04; Pearson chi2). Eighty two percent of mothers in upper social class (group 1) and only 28% of mothers in low social class (group 5) (classified by The Danish National Center of Social Research) are breastfeeding at discharge (p=0,000 by logistic regression) (active and non active groups). Duration of breastfeeding within the "active group": At term (GA 40. weeks CA) 85% are breastfed, at 2 months CA 50% are breastfed and at 4 months CA age only 20% are breastfed. There is no difference in breastfeeding-duration with or without fortification after discharge (Kaplan-Meier estimates). There is a risk of shortened breastfeeding-duration if the mother is below the age of 30 years (p=0,012), gave birth to twins or triplets (p=0,001) or the infant is SGA at birth (p=0,026) (stratified cox regression).