ESPE Abstracts

Reports on preterm born young adults’ bone health give conflicting results. Lower areal bone mineral density in the preterm born population has partly been explained by their smaller adult size. Male sex has previously been reported as a risk factor for impaired bone health in preterm born adults. We performed a bone mineral density measurement of the lumbar spine and both hips with DXA in 37 preterm born young adults, of whom 22 were women and 15 men, at a mean age of 23.6 (SD 0.74) years. Adults born at or before 32 gestation weeks or before 34 gestation weeks with a birth weight < 1500g were included in the study, and the mean gestational age at birth was 30.5 (SD 1.36) weeks. One man had low bone mineral density due to another congenital health issue besides prematurity and was excluded from final analysis. Age and gender specific Z-scores were used in analysis. Independent samples t-test for normally and Mann-Whitney U-test for non-normally distributed variables were used. In the lumbar spine, areal bone mineral density (aBMD, g/cm²) was similar between genders, but we found a significant difference in lumbar spine (L1-L4) Z-score in favor of the preterm born young women. In women, the median lumbar spine Z-score was 0.2 (IQR 1.0), in men the median Z-score was –0.500 (IQR 1.2), Mann-Whitney U-test P = 0.041. The same trend was seen in Z-scores of individual vertebrae L1 (mean in women –0.023, mean in men –0.693, mean difference in Z-score 0.670, 95% CI 0.111 to 1.230, P = 0.020) and L3 (median in women 0.150 (IQR 1.2), median in men –0.400 (IQR 1.4), Mann-Whitney U-test P = 0.011). Bone mineral densities were similar between genders in vertebrae L2 and L4. Areal bone mineral densities and Z-scores in the femoral neck were similar between genders. Gestational age at birth or birth size did not correlate with aBMD or Z-scores either in the lumbar spine or the femoral neck. The amount of self-reported sports activity was comparable between genders.

Conclusion: Preterm born young men appear to have an increased risk for lower lumbar spine bone mineral density compared to preterm born young women. The reason for the difference between genders is not apparent and warrants further study.