Pre- and post-discharge feeding of very preterm infants: impact on growth and bone mineralization

In this prospective study we examined (1) how the nutritional status of very preterm infants, judged by growth measures and biochemical values, evolved during the initial hospitalization; (2) the effect of feeding on growth after discharge from hospital; and (3) the risk factors associated with low lumbar bone mineral content (BMC) later in infancy. Sixty-four former preterm infants had their lumbar spine (L2-L4) BMC assessed by dual energy X-ray absorptiometry when they weighed between 5 and 7 kg. Predicted BMC values were calculated based on our previously reported reference lumbar BMC data. These values were used to convert the preterm infants' BMC values into percentages. The extremely preterm group (gestational age < or =28 weeks) had significantly more respiratory morbidity and longer duration of hospital stay than the more mature infants. Both groups developed growth retardation and malnutrition during the hospital stay. Exclusive breastfeeding after discharge from hospital supported linear catch-up growth and weight gain but was associated with a 7.0 (1.2-41.7)-fold risk of having low BMC values. The other factors associated with the risk of having low BMC values later in infancy were low serum phosphate levels at 6 weeks, with a 7.8 (1.6-37.0)-fold risk, and male gender, with a 4.3 (1.2-16.1)-fold risk. Appropriately designed interventional studies are needed to improve the growth and nutrition of these infants during initial hospitalization. In order to improve the postdischarge nutrition, we suggest that the amount and duration of multicomponent human milk fortification should be studied further to provide individualized nutrition throughout the catch-up growth period until the end of the first year of life.