One of the neonatologist's greatest challenges is ensuring that the premature infant has adequate growth and is provided with a correct supply of nutrients. Thanks to the establishment of the INTERGROWTH-21st Preterm Postnatal Growth Standards, created longitudinally and prospectively on healthy premature babies, it now appears evident that preterms' growth follows a pattern different from that of a fetus of the same gestational age. In addition to growth, defined solely as weight gain, further significance must be given to the quality of growth, that is, lean mass apposition. This should be evaluated in every clinical setting, using repeated standardized length and head circumference measurements, not only whether sophisticated dedicated equipment is available. Mother's milk, in addition to the countless already-known benefits, is also the perfect nourishment for premature babies, promoting lean mass apposition. In addition, with a still unclear mechanism called the "breastfeeding paradox," breast milk intake promotes preterms' neurocognitive development, even despite an initial lower weight gain. Since breast milk cannot always meet preterm infants' nutritional needs, breast milk fortification during hospitalization is a common practice. However, no clear benefit in continuing breast milk fortification after discharge has been demonstrated. When addressing the growth of a premature infant fed with human milk, the "breastfeeding paradox" must be taken into consideration to avoid excessive and unjustified supplementation of formula milk, both during the hospital stay and after discharge.
Keywords: body composition; growth; human milk; preterm infant.