What is known: • Metabolic bone disease is one of the possible long term adverse outcomes after preterm birth. • Metacarpal speed of sound (mcSOS) and metacarpal bone transmission time (mcBTT) decline in the early postnatal period.

What is new: • During follow-up, mcSOS further decreased and reached its lowest point at 12 months, while the mcBTT reached a plateau up to 24 months. • Postnatal nutrition in relation to comorbidity does not meet the optimal mineralization rate of the developing preterm bone.