ESPE Abstracts

Background and Aims: Extreme preterm birth (EPB), <30 weeks gestation, significantly impacts skeletal development due to decreased bone mineralization, with approximately 16-40% of EPBs developing metabolic bone disease of prematurity (MBDP). To investigate if MBDP persists into childhood with the current feeding protocols for EPBs, our objective was to compare bone mineral density (BMD) around (corrected) age 5 years in EPB children versus children born term.

Methods: We included 108 EPB children and 269 healthy term-born children of two observational cohort studies in the Netherlands. We prospectively determined BMD of the total body less head (TBLH) by Dual-energy X-ray Absorptiometry (DXA) around age 5 years. Age- and sex-adjusted Standard Deviation Scores (SDS) were calculated for both cohorts. Student t-test was used to compare BMD_TBLH SDS between both cohorts. Multiple linear regression analyses were performed to evaluate which birth, maternal, neonatal, child and growth characteristics are associated with BMD_TBLH SDS in both cohorts. Analysis of covariance (ANCOVA) was performed to analyze the difference of BMD_TBLH SDS between cohorts, while corrected for significant variables found in the regression analyses.

Results: At around 5 years, EPB children had lower mean (SD) length SDS, weight-for-height SDS, lean body mass (LBM) SDS, fat mass (FM) SDS and a lower BMD_TBLH SDS compared to term-born children (-0.41 (1.2) vs. 0.04 (1.1), P <0.001). Length SDS (β=0.57, P <0.001) (β=0.49, P <0.001), weight-for-length SDS (β=0.29, P <0.001) (β=0.43, P <0.001), LBM SDS (β=0.57, P <0.001) (β=0.56, P <0.001) and FM SDS (both cohorts β=0.25, P <0.001) were positively associated with BMD_TBLH SDS in EPB children and term-born children, respectively. Non-Caucasian ethnicity was only positively associated in EPB children (β=0.20, P = 0.008). Birth, maternal and neonatal characteristics were not associated with BMD_TBLH SDS at around 5 years. The ANCOVA analyses, including length SDS, weight-for-length SDS, LBM SDS and FM SDS as covariates, found no difference in BMD_TBLH SDS between EPB children and term-born children (-0.07 (95% confidence interval (CI) -0.23 – 0.09) vs. -0.09 (95% CI -0.18 – 0.01), P = 0.85).

Conclusion: EPB children have a lower BMD_TBLH SDS around (corrected) age 5 years compared to term-born children. However, BMD_TBLH SDS was well in the normal range in both cohorts. Lower BMD_TBLH SDS in EPB children seems not to be caused by the bone itself, but explained by anthropometrics and body composition parameters, especially lower length SDS and LBM SDS. Indicating that, under current feeding protocol, MBDP generally does not persist into young childhood.