Longitudinal course of bone health from infancy to mid-adulthood in preterm and term-born individuals.

Preterm birth is associated with various health consequences. However, the long-term impact on bone health remains unclear. This study compares bone health from infancy into mid-adulthood between preterm and term-born individuals and explores potential association with fracture status. Data from the Zurich Longitudinal Studies were analyzed, including preterm and term-born individuals (enrolled 1974-1979). Bone health was measured longitudinally using the Bone Health Index (BHI) from hand X-rays analyzed by BoneXpert. Fracture history was obtained through parental interviews and self-reports. Generalized estimating equation models evaluated BHI over age, adjusting for age, sex, preterm and fracture status. 1582 X-rays from 95 term and 120 preterm individuals, across 17 time points (3 months to 47 years of age) were analyzed. Preterm individuals (median gestational age 34.1 weeks, IQR ± 3.1) had significantly lower BHI than term-born peers (p = 0.016), with a deficit persisting until 4.5 years of age. Thereafter no difference was found. No significant association between BHI and fracture status in mid-adulthood was found (p = 0.43). In this cohort of predominantly moderate to late preterm infants, catch-up in bone health was achieved in early childhood and maintained into mid-adulthood. How bone health and fracture status evolve in later life remains unclear and requires a lifespan perspective on preterm birth.