Growth from birth to adolescence and bone mineral density in young adults: The 1993 Pelotas birth cohort

Evaluating the associations of adult heel BMD with birth weight and growth parameters at age 10 in UK Biobank cohort

OBJECTIVE

This study was aimed to evaluate the associations of adult heel bone mineral density (BMD) with birth weight and growth parameters at the age of ten years.

METHODS

The analysis data (97178-178,494 subjects) was derived from the UK Biobank cohort. Birth weight, comparative body size and height size at the age of ten years were determined by self-report. The heel BMD was estimated by the Quantitative Ultrasound Index through the calcaneus. Linear regression analysis was applied to test the associations of adult heel BMD with birth weight and growth parameters at the age of ten years, respectively. Age, sex, body mass index and 10 principle components (PC) of population structure were used as covariates in the regression analysis of total samples. In sex-specific analysis, age, body mass index and 10 PC were used as covariates.

RESULTS

We observed significant associations of heel BMD with birth weight (b = -0.020, P = 1.974 × 10^-13), comparative body size (b = 0.020, P = 2.539 × 10^-6) and comparative height size (b = -0.020, P = 5.892 × 10^-11) at the age of ten years in total samples. In females, birth weight (b = -0.040, P = 2.870 × 10^-24) and comparative height size (b = -0.040, P = 2.034 × 10^-20) were statistically associated with adult heel BMD. In males, comparative body size appeared to be associated with adult heel BMD (b = 0.030, P = 1.590 × 10^-7).

CONCLUSION

Our study results support the predictive effects of birth weight and growth parameters at the age of ten years on adult heel BMD. We also observed sex-specific association between adult heel BMD and growth parameters at the age of ten years.

Birth weight is positively associated with adult osteoporosis risk: observational and Mendelian randomization studies

The relationship between birth weight and osteoporosis was inconsistent in previous observational studies. Therefore, we performed a systematic evaluation to determine the inconsistent relationship and further make causal inference based on the UK Biobank datasets (~500,000 individuals) and individual/summary-level genetic datasets. Observational analyses found consistent negative associations either between birth weight and estimated bone mineral density (eBMD) or between genetic risk score (GRS) of birth weight and eBMD in total subjects, and sex-stratified subgroups. Mediation analyses detected significant mediation effects of adult weight and height on associations between birth weight and eBMD. Birth weight was causally associated not only with three BMD phenotypes (eBMD, total body [TB]-BMD, and femoral neck [FN]-BMD) under two effect models (total and fetal effect), but also with the risk of fracture using different Mendelian randomization (MR) methods. Multivariable MR analyses detected the pleiotropic effects of some environmental factors (e.g., gestational duration, head circumference, hip circumference) on the associations between birth weight and BMD/fracture. Three BMD phenotypes (eBMD, TB-BMD, and FN-BMD) have significant mediation effects on the associations between birth weight and fracture by using a novel mediation MR analysis under the multivariable MR framework. This multistage systematic study found consistent causal associations between birth weight and osteoporosis risk, fetal origin of genetic effects underlying the associations, and several mediation factors on the detected associations. The results enhanced our understanding of the effects of fetal original phenotypes on outcomes in late adulthood and provided helpful clues for early prevention research on osteoporosis. © 2021 American Society for Bone and Mineral Research (ASBMR).