Preterm birth does not affect bone mineral density in young adults

Objective: Previous studies showed conflicting data on the effect of prematurity on bone mineral density (BMD) in infants and children. Only a few studies investigated the long-term effects of prematurity on BMD in early adulthood. The objective of our study was to assess the long-term effects of preterm birth on BMD of the total body (BMDTB), lumbar spine (BMDLS) and bone mineral apparent density of the LS (BMAD(LS)). Design: Cross-sectional study. Methods: It consists of two hundred and seventy-six healthy subjects without serious postnatal complications, aged 18-24 years. The contribution of gestational age to the variance in BMD in young adulthood and the differences in BMD between 151 subjects born preterm (median gestational age 32.2 weeks (interquartile range (IQR) 30.3-34.0)) and 125 subjects born at term(median gestational age 40.0 weeks (IQR 39.0-40.0)) were investigated. BMD was determined by dual-energy X-ray absorptiometry. Results: There were no significant linear correlations between gestational age and BMDTB (r = 0.063, P = 0.30), BMDLS (r = 0.062, P = 0.31) and BMAD(LS) (r = 0.069, P = 0.26). Also after adjustment for possible confounders, gestational age was no significant contributor to the variance in BMDTB (P = 0.27), BMDLS (P = 0.91) and BMAD(LS) (P = 0.87). No significant differences were found between preterm and term subjects with regard to BMDTB, BMDLS and BMAD(LS). Conclusion: In our cohort of 276 young adults, aged 18-24 years, gestational age was not a significant determinant in the variance of BMD. Preterm birth without serious postnatal complications is not associated with a lower BMD in young adulthood.