Abstract
PURPOSE: To examine the association between birth characteristics and bone mineral density (BMD) and bone mineral content (BMC) in young adults. METHODS: Data from 3,174 participants aged 20-54 years from the 3rd (2006-2008) and 4th (2017-2019) HUNT Study surveys were linked to the Medical Birth Registry of Norway. BMD and BMC of femoral neck were measured using dual-energy X-ray absorptiometry (DXA). Linear regression estimated mean differences in BMD and BMC by birth characteristics, adjusting for sex, birth year, age at scan, maternal age, and maternal morbidity. RESULTS: At bone densitometry, participants had a mean age of 34.2 years, with mean BMD of 0.971 g/cm(2), and mean BMC of 5.398 g, at the femoral neck. A standard deviation (SD) increase in ponderal index (PI) and birth weight was associated with higher BMD of 0.024 g/cm(2) (95% CI 0.006, 0.042) and 0.015 g/cm(2) (95% CI 0.009, 0.022). Individuals born large for gestational age (LGA) had 0.023 g/cm(2) (95% CI 0.007, 0.039) higher BMD than those born appropriate for gestational age (AGA), while low birth weight (LBW)(< 2.5 kg) was associated with - 0.028 g/cm(2) (95% CI - 0.053, - 0.003) lower BMD. For BMC, an SD increase in PI and birth weight was associated with 0.171 g (95% CI 0.048, 0.293) and 0.146 g (95% CI 0.112, 0.181) higher BMC, respectively. LGA had 0.206 g (95% CI 0.090, 0.313) higher BMC, while LBW was associated with - 0.298 g (95% CI - 0.469, - 0.127) lower BMC. CONCLUSION: Higher ponderal index, birth weight, and gestational age were positively associated with BMD and BMC in young adulthood.