Postnatal modulation of body composition in preterm infants by human growth factors and hormones in relation to various nutrient compositions.

Preterm infants are almost universally faced with postnatal growth restriction.
Preterm birth, as well as postnatal growth restriction, is associated with
impaired neurodevelopmental outcome. Furthermore preterm infants are prone to
develop risk factors for the onset of the metabolic syndrome. Postnatal growth
patterns, e.g. catch-up growth with rapid weight gain, have been associated
with an increased risk for the development of risk factors for the metabolic
syndrome. By limiting postnatal growth restriction early nutritional
interventions could be a key in improving long-term outcomes of preterm
infants. Indeed it has been shown that nutritional interventions can influence
neurodevelopment and the onset of risk factors for the metabolic syndrome.
Insulin-like growth factor I (IGF-I) is one of the key factors in the endocrine
regulation of growth. After birth IGF-I levels quickly drop as the placental
supply is suddenly disrupted, to then slowly be restored in preterm infants. We
hypothesize that IGF I has to reach a certain threshold before it can
effectively influence growth, which might explain the need for a high-energy
and high-nutrient diet in the early postnatal period. On the other hand, we
hypothesize that less energy- and nutrient-enrichment is required once IGF-I
passes the threshold concentration. At this level the maximum growth rate is
expected to be potentiated by IGF-I, reducing the need for extra nutrients and
potentially leading to increased fat deposition if diet enrichment is
continued. Nonetheless, currently there is no full understanding of the
endocrine regulation of growth in preterm infants.

The primary objectives of this study is to study the endocrine regulation of
growth in preterm infants.
Secondary objectives are to study the influence of the endocrine regulation
and early nutritional intake on neurodevelopmental outcome, bone
mineralization, lipid profile and blood pressure in preterm infants.

Cohort study

Infants will be randomized to either preterm follow-up formula or standard care
at a postmenstrual age of 32-33 weeks.

During hospitalisation infants will be subjected to weekly blood draws and
anthropometric measurements. Since these preterm infants will be admitted to
the Neonatal Intensive Care Unit (NICU)blood draws for research purposes will
be combined with blood sampling necessary for clinical care. Infants will be
followed up at the outpatient department at term age and 3, 6, 12 and 24 months
corrected age for continued anthropometric measurements, body composition and
bone mineralization measurements, blood pressure registration, neuropsychologic
assessment and a total of 2 blood draws. The burden of the intervention is
expected to be minimal and is anticipated to improve long-term outcomes
compared to standard care. Due to the nature of the study it is not feasible to
conduct the research in another group than preterm infants.