ESPE Yearbook of Paediatric Endocrinology

Journal of Bone and Mineral Research. 2025, 40(3), 382-395. https://doi.org/10.1093/jbmr/zjaf011

Brief Summary: This Finnish nationwide register-linkage cohort study examined the association between gestational age and the likelihood of experiencing a bone fracture in over 223,000 individuals from birth to almost 30 years of age. Surprisingly, individuals, particularly males, born extremely preterm (before 28 weeks) or very preterm (between 28 and 31 weeks) had a lower risk of bone fractures than those born at full term.

Commentary: This study reports the long-term musculoskeletal health of people born prematurely. Given the well-established link between prematurity and reduced bone mineral density (BMD), one might expect higher fracture rates in preterm individuals. However, the data suggest the opposite: individuals born at the earliest gestations, particularly males, were less likely to sustain fractures by early adulthood. These findings challenge the assumption that lower BMD necessarily equates to a higher fracture risk in young populations.

These findings may be explained in several ways. It has been suggested that children born preterm may be less socially active and exhibit less externalising behaviour or sensation seeking. They may also be less likely to take risks than their counterparts born at or near term. Additionally, parents of children born preterm tend to be more overprotective than parents of children born at term. Furthermore, children born preterm may have motor impairments that affect their ability to engage in physical activities. All of these factors could be a plausible explanation for the above findings. However, certain limitations need to be kept in mind. A lack of information on maternal dietary status, childhood lifestyle, dietary status, breastfeeding, vitamin D supplementation and the growth of the index child during childhood and puberty could all be possible confounding factors. The reliability of gestational age must be considered, as prior to 1987–1990, it was determined by the last menstrual period. This could have led to an underestimation of preterm births. The generalisability of the findings may also be affected by the lack of details regarding prenatal and postnatal treatments at that time, as well as the ethnic homogeneity of the Finnish population. Therefore, the results should be interpreted with caution.

This study adds nuance to our understanding of the long-term skeletal outcomes of preterm birth, inviting further research into the behavioural, environmental and physiological factors that shape fracture risk throughout life.