The influence of birth weight and length on bone mineral density and content in adolescence: The Tromsø Study, Fit Futures
The influence of birth weight and length on bone mineral parameters in adolescence is unclear. We found a positive association between birth size and bone mineral content, attenuated by lifestyle factors. This highlights the impact of environmental stimuli and lifestyle during growth.
The influence of birth weight and length on bone mineral density and content later in life is unclear, especially in adolescence. This study evaluated the impact of birth weight and length on bone mineral density and content among adolescents.
We included 961 participants from the population-based Fit Futures study (2010–2011). Dual-energy X-ray absorptiometry (DXA) was used to measure bone mineral density (BMD) and bone mineral content (BMC) at femoral neck (FN), total hip (TH) and total body (TB). BMD and BMC measures were linked with birth weight and length ascertained from the Medical Birth Registry of Norway. Linear regression models were used to investigate the influence of birth parameters on BMD and BMC.
Birth weight was positively associated with BMD-TB and BMC at all sites among girls; standardized β coefficients [95% CI] were 0.11 [0.01, 0.20] for BMD-TB and 0.15 [0.06, 0.24], 0.18 [0.09, 0.28] and 0.29 [0.20, 0.38] for BMC-FN, TH and TB, respectively. In boys, birth weight was positively associated with BMC at all sites with estimates of 0.10 [0.01, 0.19], 0.12 [0.03, 0.21] and 0.15 [0.07, 0.24] for FN, TH and TB, respectively. Corresponding analyses using birth length as exposure gave significantly positive associations with BMC at all sites in both sexes. The significant positive association between birth weight and BMC-TB in girls, and birth length and BMC-TB in boys remained after multivariable adjustment.
We found a positive association between birth size and BMC in adolescence. However, this association was attenuated after adjustment for weight, height and physical activity during adolescence.
KeywordsBirth weight DXA Osteoporosis Humans Bone density
We are grateful to the study participants, the staff at the Clinical Research Unit at the University Hospital of North Norway (UNN HF) and the Fit Futures administration for conducting the study. We thank Robert Kechter at Finnmark Hospital Trust, Carsten Rolland at the School of Sport Sciences, UiT The Arctic University of Norway, and the Garvan Institute of Medical Research for office and administration contributions. We also thank the Norwegian Osteoporosis Association for supporting paediatric software and the Northern Norway Regional Health Authorities for funding this work.
Study design: TC, AW, LAA and NE. Study conduct: A-SF, GG and NE. Data collection: TC, A-SF, GG, NE, O-AN and AW. Data analysis: TC, LAA and NE. Data interpretation: TC, LAA, EMD and NE. Drafting the manuscript: TC, LAA and NE. Revising the manuscript content: TC, LAA, AKD, EMD, EKE, A-SF, LG-M, GG, O-AN, BS, GST, DV, AW and NE. Approving the final version of the manuscript TC, LAA, AKD, EMD, EKE, A-SF, LG-M, GG, O-AN, BS, GST, DV, AW and NE. TC, LAA and NE take responsibility for the integrity of the data analysis.
Compliance with ethical standards
The study was approved by The Norwegian Data Protection Authority (reference number 2009/1282) and by The Regional Committee of Medical and Health Research Ethics (reference number 2011/1702/REKnord).
The Northern Norway Regional Health Authorities (SFP1160-14) funded this study. The funders had no role in the study design, data collection, analysis, interpretation or decision to submit this manuscript for publication.
Conflicts of interest
- 23.Norwegian Institute of Public Health (2016) Medical Birth Registry of Norway. [cited 2016 9 Dec]; Available from: https://www.fhi.no/en/hn/health-registries/medical-birth-registry-of-norway/
- 39.World Health Organization (2004) Low birthweight—country, regional and global estimates. [cited 2016 9 Dec]; Available from: http://apps.who.int/iris/bitstream/10665/43184/1/9280638327.pdf