Growth in childhood predicts hip fracture risk in later life

Preterm birth and risk of bone fractures during childhood and early adulthood

People born preterm have reduced BMD, subnormal peak bone mass, and an increased risk of osteoporosis. Whether this translates to increased risk of bone fractures is uncertain. We assessed fracture risk from childhood to early adulthood in relation to gestational age and sex by conducting a nationwide register-linkage cohort study comprising all 223 615 liveborn (January 1987-September 1990) singletons (9161, 4.1%; preterm) in Finland. Cox regression models provided hazard ratios (HRs) for fracture diagnosis in public specialty health care in both first and recurrent event settings during the whole follow-up (0-29 years) and during different age periods (0-4, 5-9, 10-29 years). Gestational age was considered categorical (full-term, 39-41 weeks; reference). A total of 39 223 (17.5%) children or young adults had at least 1 fracture. In analyses not stratified by sex, only extremely preterm birth (<28 completed weeks' gestation) was associated with risk of bone fracture at 0-29 years (adjusted HR [aHR]: 0.46; 95% CI: 0.28-0.74) compared with those born full-term. Among females, gestational age was unrelated to fracture risk at 0-29 years. Among males, extremely and very preterm (28-31 weeks) birth was associated with lower risk of fracture at 0-29 years compared with those born full-term (aHR: 0.38 [95% CI: 0.21-0.71] and 0.75 [95% CI: 0.59-0.95], respectively). Restricting the analyses to the individuals without severe medical condition(s) attenuated the associations. However, the fracture risk varied according age and sex: at 10-29 years, moderately preterm (32-33 weeks) females and extremely and very preterm males had a lower risk (aHR: 0.63 [0.43-0.94], 0.35 [0.17-0.69], and 0.74 [0.57-0.95], respectively), while late-preterm birth (34-36 weeks) was associated with a 1.6-fold higher risk among females at 0-5 years, and a 1.4-fold risk among males at 5-10 years. Analyses on recurrent fractures showed a similar pattern. Children and young adults, in particular males, born extremely or very preterm may have fewer bone fractures; this is partly explained by severe medical conditions in this group.

School Lunch and Body Size in Japanese Junior High School Students: The Japanese National Health and Nutrition Survey

Objectives: Although the school lunch program is expected to reduce obesity and underweight among children in Japan, there had been no individual-level study examining the impact of school lunch on body size (overweight or underweight). The present study examined the association between school lunch and body size in Japanese junior high school students. Methods: This cross-sectional study was conducted based on data from the Japanese National Health and Nutrition Survey in 2014 and 2018. The present analysis included 323 individuals (12-15 years old). The exposure factor was school lunch usage. The primary outcome measure was body size (normal weight, overweight/obesity (including both overweight and obesity), and underweight). Results: Of 323 individuals, the proportion of school lunch users was 65.6%. School lunch was not statistically significantly associated with normal weight; the multivariate-adjusted odds ratio (95% confidence interval) of normal weight in school lunch users was 1.07 (0.66-1.75) in comparison with non-users. No significant associations were found for overweight/obesity or underweight outcomes. Conclusions: The present findings did not support the expectation for the Japanese school lunch program.

Is there an association between birth characteristics and fractures in young adults? The HUNT Study, Norway

This population study investigated the association between birth characteristics and fracture risk in 11,099 young adults (aged 19-54 years). Our findings indicate that birth weight, gestational age, and birth weight for gestational age were not associated with fractures in the wrist, humerus, hip, and spine in this population.

PURPOSE

Skeletal development starts during fetal life, and it is estimated that most bone formation occurs in the 3rd trimester. This study examined the association between birth characteristics and fractures of the wrist, humerus, hip, and spine, in young adults (19-54 years).

METHODS

11.099 participants in the 3rd survey of the HUNT Study (2006-2008) were linked with the Medical Birth Registry of Norway and hospital records. Fractures of the wrist, humerus, hip, and spine were identified using ICD9/10 codes between 1988 and 2021. Follow-up was from date of participation in HUNT until a first fracture, emigration, death, or end of study. Cox regression was used to estimate hazard ratios (HR) of fracture associated with birth characteristics (95% CI), adjusted for birth year, sex, maternal age, and maternal morbidity. In a secondary analysis, follow-up started in 1988.

RESULTS

During a median follow-up of 14.0 years (153,657 person-years), 290 fractures occurred. Mean age at first fracture was 41.4 years (SD 7.4). Overall, there were no clear associations between birth characteristics and fractures in these data. HR for fracture was 0.43 (0.15-1.24) for those with a birth weight < 2.5 kg (reference birth weight 3.5 - 3.9 kg); 1.04 (0.74 - 1.46) for those born small for gestational age (< 10th percentile, reference 10 - 90th percentile); and 0.63 (0.33 - 1.23) for those born preterm (reference term births). The secondary analysis from 1988, including 539 fractures, gave similar results as the main analysis.

CONCLUSION

Birth weight, gestational age, or birth weight for gestational age was not associated with an increased risk of fractures of the wrist, humerus, hip, and spine in young adults.

Explaining declining hip fracture rates in Norway: a population-based modelling study

Background

Although age-standardised hip fracture incidence has declined in many countries during recent decades, the number of fractures is forecast to increase as the population ages. Understanding the drivers behind this decline is essential to inform policy for targeted preventive measures. We aimed to quantify how much of this decline could be explained by temporal trends in major risk factors and osteoporosis treatment.

Methods

We developed a new modelling approach, Hip-IMPACT, based on the validated IMPACT coronary heart disease models. The model applied sex- and age stratified hip fracture numbers and prevalence of pharmacologic treatments and risk/preventive factors in 1999 and 2019, and best available evidence for independent relative risks of hip fracture associated with each treatment and risk/preventive factor.

Findings

Hip-IMPACT explained 91% (2500/2756) of the declining hip fracture rates during 1999-2019. Two-thirds of the total decline was attributed to changes in risk/preventive factors and one-fifth to osteoporosis medication. Increased prevalence of total hip replacements explained 474/2756 (17%), increased body mass index 698/2756 (25%), and increased physical activity 434/2756 (16%). Reduced smoking explained 293/2756 (11%), and reduced benzodiazepine use explained (366/2756) 13%. Increased uptake of alendronate, zoledronic acid, and denosumab explained 307/2756 (11%), 104/2756 (4%) and 161/2756 (6%), respectively. The explained decline was partially offset by increased prevalence of type 2 diabetes and users of glucocorticoids, z-drugs, and opioids.

Interpretation

Two-thirds of the decline in hip fractures from 1999 to 2019 was attributed to reductions in major risk factors and approximately one-fifth to osteoporosis medication.

Funding

The Research Council of Norway.

Prenatal exposure to polybrominated diphenyl ethers and birth outcomes

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) were used as flame retardants and from their end-use products they can be released to accumulate within indoor environments. This may result in exposures to pregnant women with potential adverse effects on the developing fetus. While studies have shown associations between prenatal PBDE exposure and poor birth outcomes, research has mainly focused on birth weight and gestational age and may miss important indicators of newborn size.

METHODS

The sample included a cohort of Dominican and African American mother-child pairs from New York City recruited from 1998 to 2006. PBDE congeners (BDE-47, BDE-99, BDE-100, and BDE-153) were measured in cord serum at birth and dichotomized into low (<80th percentile) and high (>80th percentile) categories. Weight, length, head circumference, and gestational age were measured at birth and the ponderal index (birth weight/length x 100), size for gestational age, and population-based z-scores were calculated (n = 305). Separate regression analyses were conducted to estimate associations between PBDEs or PBDE sum (ng/g lipid) and birth outcomes. Quantile g-computation was performed to estimate the effect of total PBDE mixture. We also assessed effect modification by sex and ethnicity.

RESULTS

Adjusting for relevant covariates, the high exposure category of BDE-153 was associated with lower birth weight z-score (-0.25, 95% CI: -0.5, 0.0) and longer gestation (0.43 weeks, 95% CI: 0.07, 0.79). The high exposure category of BDE-99 was associated with lower birth length z-score (-0.55, 95% CI: -0.98, -0.12). There was a negative association between the overall PBDE mixture and birth length z-score (-0.10, 95% CI: -0.21, 0.00) per 1 quintile increase in PBDEs. There was no effect modification by sex or ethnicity.

CONCLUSIONS

These results suggest that prenatal exposures to BDE-153, BDE-99, and total PBDE mixture are associated with birth outcomes in a cohort of Dominican and African American newborns.

Postnatal Protein Intake as a Determinant of Skeletal Muscle Structure and Function in Mice-A Pilot Study

Sarcopenia is characterised by an age-related decrease in the number of muscle fibres and additional weakening of the remaining fibres, resulting in a reduction in muscle mass and function. Many studies associate poor maternal nutrition during gestation and/or lactation with altered skeletal muscle homeostasis in the offspring and the development of sarcopenia. The aim of this study was to determine whether the musculoskeletal physiology in offspring born to mouse dams fed a low-protein diet during pregnancy was altered and whether any physiological changes could be modulated by the nutritional protein content in early postnatal stages. Thy1-YFP female mice were fed ad libitum on either a normal (20%) or a low-protein (5%) diet. Newborn pups were cross-fostered to different lactating dams (maintained on a 20% or 5% diet) to generate three groups analysed at weaning (21 days): Normal-to-Normal (NN), Normal-to-Low (NL) and Low-to-Normal (LN). Further offspring were maintained ad libitum on the same diet as during lactation until 12 weeks of age, creating another three groups (NNN, NLL, LNN). Mice on a low protein diet postnatally (NL, NLL) exhibited a significant reduction in body and muscle weight persisting up to 12 weeks, unlike mice on a low protein diet only prenatally (LN, LNN). Muscle fibre size was reduced in mice from the NL but not LN group, showing recovery at 12 weeks of age. Muscle force was reduced in NLL mice, concomitant with changes in the NMJ site and changes in atrophy-related and myosin genes. In addition, μCT scans of mouse tibiae at 12 weeks of age revealed changes in bone mass and morphology, resulting in a higher bone mass in the NLL group than the control NNN group. Finally, changes in the expression of miR-133 in the muscle of NLL mice suggest a regulatory role for this microRNA in muscle development in response to postnatal diet changes. Overall, this data shows that a low maternal protein diet and early postnatal life low-protein intake in mice can impact skeletal muscle physiology and function in early life while postnatal low protein diet favours bone integrity in adulthood.

Acquisition of peak bone mass

Peak bone mass (PBM) is a key determinant of bone mass and fragility fractures later in life. The increase in bone mass during childhood and adolescence is mainly related to an increase in bone size rather to changes in volumetric bone density. Race, gender, and genetic factors are the main determinants of PBM achievement. Nevertheless, environmental factors such as physical activity, calcium and protein intakes, weight and age at menarche, are also playing an important role in bone mass accrual during growth. Therefore, optimization of calcium and protein intakes and weight-bearing physical activity during growth is an important strategy for optimal acquisition of PBM and bone strength and for contributing to prevent fractures later in life.

Potential influences on optimizing long-term musculoskeletal health in children and adolescents with X-linked hypophosphatemia (XLH)

In recent years, much progress has been made in understanding the mechanisms of bone growth and development over a lifespan, including the crosstalk between muscle and bone, to achieve optimal structure and function. While there have been significant advances in understanding how to help improve and maintain bone health in normal individuals, there is limited knowledge on whether these mechanisms apply or are compromised in pathological states. X-linked hypophosphatemia (XLH) (ORPHA:89936) is a rare, heritable, renal phosphate-wasting disorder. The resultant chronic hypophosphatemia leads to progressive deterioration in musculoskeletal function, including impaired growth, rickets, and limb deformities in children, as well as lifelong osteomalacia with reduced bone quality and impaired muscle structure and function. The clinical manifestations of the disease vary both in presentation and severity in affected individuals, and many of the consequences of childhood defects persist into adulthood, causing significant morbidity that impacts physical function and quality of life. Intervention to restore phosphate levels early in life during the critical stages of skeletal development in children with XLH could optimize growth and may prevent or reduce bone deformities in childhood. A healthier bone structure, together with improved muscle function, can lead to physical activity enhancing musculoskeletal health throughout life. In adults, continued management may help to maintain the positive effects acquired from childhood treatment, thereby slowing or halting disease progression. In this review, we summarize the opinions from members of a working group with expertise in pediatrics, epidemiology, and bone, joint and muscle biology, on potential outcomes for people with XLH, who have been optimally treated from an early age and continue treatment throughout life.

Plaster of Paris: Squeeze, But Not Too Hard!

Plaster of Paris (PoP) has been the predominant treatment option for most acute and chronic orthopedic conditions. Water immersion significantly decreases the PoP bandage strength. Moreover, concerns have been raised about the possibility of breaks in PoP splints and cast failures once solid. The current study was designed to account for the increase in weight associated with increased PoP layers. The authors hypothesized that by controlling for weight variation as layers increased, they could determine the number of layers of PoP bandage that truly results in optimal mechanical properties. They assessed whether adequate plaster weight control while increasing layers could improve the mechanical properties of the splint. [Orthopedics. 2022;45(1):e57-e61.].

Nutrition in adolescent growth and development

During adolescence, growth and development are transformative and have profound consequences on an individual's health in later life, as well as the health of any potential children. The current generation of adolescents is growing up at a time of unprecedented change in food environments, whereby nutritional problems of micronutrient deficiency and food insecurity persist, and overweight and obesity are burgeoning. In a context of pervasive policy neglect, research on nutrition during adolescence specifically has been underinvested, compared with such research in other age groups, which has inhibited the development of adolescent-responsive nutritional policies. One consequence has been the absence of an integrated perspective on adolescent growth and development, and the role that nutrition plays. Through late childhood and early adolescence, nutrition has a formative role in the timing and pattern of puberty, with consequences for adult height, muscle, and fat mass accrual, as well as risk of non-communicable diseases in later life. Nutritional effects in adolescent development extend beyond musculoskeletal growth, to cardiorespiratory fitness, neurodevelopment, and immunity. High rates of early adolescent pregnancy in many countries continue to jeopardise the growth and nutrition of female adolescents, with consequences that extend to the next generation. Adolescence is a nutrition-sensitive phase for growth, in which the benefits of good nutrition extend to many other physiological systems.

Thirty years of hip fracture incidence in Austria: is the worst over?

Nationwide hip fracture incidence in the Austrian population was assessed over a period of 30 years (1989-2018), including 20 years data from a previous study and a recent 10 years follow-up. While absolute numbers in men continued to increase, absolute numbers in women and age-standardized incidences in both men and women decreased.

PURPOSE

In the Austrian population ≥ 50 years, nationwide hip fracture incidences over a period of 20 years (1989-2008) have shown an initial steep increase, followed by a leveling-off during the last few years of observation. The purpose of the present study was to follow up on hip fracture incidences for another 10 years (2009-2018) and to analyze trends over the entire period of 30 years.

METHODS

ICD-10 code classes S72.0, S72.1, and S72.2 were applied. All data were retrieved from the Statistics Austria database and its hospital discharge register. Annual absolute numbers, crude and age-standardized incidences, and incidence rate ratios (IRR) were stratified by sex and 5-year age intervals, and calculated by using a correction factor for multiple registrations.

RESULTS

Total number of hip fracture cases increased from 13,984 (2009) to 14,640 (2015), and decreased thereafter to 14,457 (2018), despite a persistent increase in men. Age-standardized incidences peaked at 476/100,000 (2010), followed by a decrease to 408/100,000 (2018). The observed overall decrease was mainly driven by the female population. Incidence rate ratios (IRRs) yielded a statistically significant average annual decrease of age-standardized incidences in both women and men (∆IRR 0.984; 0.981-0.987).

CONCLUSION

While absolute numbers of hip fracture in women showed a slight decrease during the last 10 years of observation, numbers in men continued to increase. Age-standardized incidences nevertheless decreased in both men and women, which may be interpreted as a trend in the right direction. However, due to the rapid aging of the population, it cannot be precluded that this trend will be compromised during the next few decades.

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.

Impact of population-based or targeted BMD interventions on fracture incidence

In a simulated population of older women, we demonstrate that an upward shift in the population distribution of BMD by approximately 0.3SD may decrease the risk of incident fractures to the same extent as an intervention targeted to those with T-score less than -2.5.

INTRODUCTION

To investigate the impact of population level or targeted alterations to BMD on the incidence of fractures.

METHODS

We used a simulated cohort of 49,242 women with age and body mass index distribution from the UK, and prevalence of other clinical risk factors based on European FRAX® cohorts. Using FRAX probabilities of major osteoporotic fracture (MOF: hip, clinical vertebral, distal forearm, proximal humerus) and hip fracture, calculated with femoral neck BMD, we determined the expected number of fractures over 10 years, stratified by 10-year age band from 50 years. We then investigated the effect of (i) uplifting all individuals with T-score below -2.5 to be exactly -2.5 (high-risk strategy) and (ii) shifting the entire BMD distribution upwards (population strategy).

RESULTS

Overall, the high-risk strategy prevented 573 MOF including 465 hip fractures. Moving the BMD T-score distribution upward by 0.27SD gave an equivalent reduction in numbers of MOF; for hip fractures prevented, this was 0.35SD. A global upward 0.25SD BMD shift prevented 524 MOF including 354 hip fractures, with corresponding figures for an increase of 0.5SD being 973 MOF prevented and 640 hip fractures prevented. The ratio of hip fracture to MOF prevented differed by the two approaches, such that for the high-risk strategy, the ratio was 0.81, and for the population strategy was 0.68 (0.25SD BMD uplift) and 0.66 (0.5SD BMD uplift). The numbers of fractures prevented by the high-risk strategy increased with age. In contrast, the age-related increase in numbers of fractures prevented with the population strategy rose with age, but peaked in the 70-79-year age band and declined thereafter.

CONCLUSIONS

Both strategies reduced the numbers of expected incident fractures, with contrasting relative impacts by age and fracture site. Whilst the current analysis used UK/European anthropometric/risk factor distributions, further analyses calibrated to the distributions in other settings globally may be readily undertaken. Overall, these findings support the investigation of both population level interventions and those targeted at high fracture risk groups.

Maternal pre-pregnancy underweight is associated with underweight and low bone mass in school-aged children

INTRODUCTION

A number of studies have reported that pre-pregnancy overweight status is associated with offspring obesity, yet only a few studies have examined pre-pregnancy underweight status as it associates with offspring health. The aim of the present study was to assess the effect of pre-pregnancy underweight status in a mother on health outcomes in her offspring. To this end, the primary outcome examined in the present study was underweight status in the offspring, with a secondary outcome of offspring low bone mass.

MATERIALS AND METHODS

The present retrospective cohort study, conducted from 2008 to 2011, targeted a source population of all students registered as fifth-graders at three public elementary schools in Hamamatsu and Fukuroi cities. Maternal height and weight before and after pregnancy and offspring weight and height at birth were obtained from the Maternal and Child Health Handbook. Offspring weight and height at age 10 years were measured using standard procedures. Offspring total body less head (TBLH) bone mineral content (BMC) was determined with a dual-energy X-ray absorptiometry scanner.

RESULTS

Pre-pregnancy underweight status was found to be associated with an increased risk of an underweight status in female offspring (OR = 2.88, 95% CI 1.06-7.81). Offspring TBLH BMC in the underweight mother group was significantly lower than that in the non-underweight mother group.

CONCLUSIONS

We determined that pre-pregnancy underweight status was more likely to lead to an underweight status and low TBLH BMC in school-aged offspring.

Traumatic fractures in China from 2012 to 2014: a National Survey of 512,187 individuals

The China National Fracture Study has been conducted to provide a national dataset of traumatic fractures across China. A national representative sample of 512,187 individuals was selected. The population-weighted incidence rates, distribution, injury mechanisms, and risk factors for traumatic fractures were identified for various groups of individuals.

INTRODUCTION

The China National Fracture Study (CNFS) has been conducted to provide a comprehensive and up-to-date national dataset of traumatic fractures across China. This study aims to report the national incidences and distributions of traumatic fractures that occurred in 2012, 2013, and 2014 and to analyze the risk factors.

METHODS

A national representative sample of individuals was selected from 24 rural counties and 24 urban cities of 8 provinces using stratified random sampling and the probability proportional to size (PPS) methodology. Participants were interviewed to identify whether they sustained traumatic fractures of the trunk and/or four extremities that had occurred in 2012, 2013, and 2014. The main risk factors associated with traumatic fractures were analyzed by multiple logistic regression models.

RESULTS

A total of 512,187 individuals, including 259,649 males and 252,538 females, participated in the CNFS. The population-weighted incidence rates of traumatic fractures in China were calculated to be 2.5 (95% CI, 2.2-2.8) per 1000 population in 2012, 2.8 (95% CI, 2.5-3.3) in 2013, and 3.2% (95% CI, 2.8-3.6) in 2014. The population-weighted incidence rates of fragility fractures among participants aged 65 years and older were calculated to be 27.4 (95% CI, 21.4-33.4) per 1000 population in 2012, 36.0 (95% CI, 28.6-43.5) in 2013, and 42.4 (95% CI, 34.9-49.9) in 2014. The most common cause of fracture was low-energy injuries, followed by traffic accidents. For all age groups, sleeping less than 7 h was a risk factor for traumatic fractures. Alcohol consumption and previous fracture history were identified as risk factors for adults aged 15 years and over. Cigarette smoking was found to be a risk factor for males aged 15-64 years old. For individuals aged 15-64 years old, underweight incurred a risk effect for males and overweight for females. Alcohol consumption, sleeping less than 7 h per day, living in the central and eastern regions, a body mass index less of than 18.5, and having a previous fracture history were identified as strong risk factors for fragility fractures.

CONCLUSION

The national incidence, distribution, and injury mechanisms for traumatic fractures were revealed in the CNFS. Risk factors were identified for various groups of individuals.

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

BACKGROUND

The study examined the association of body size (weight and length) at birth and gain in height and weight during childhood and adolescence with areal bone mineral density (aBMD) in adulthood for women and men.

METHODS

756 members (335 men and 421 women) of the 1993 Pelotas (Brazil) Birth cohort were studied. Data on weight and length/height were obtained at birth and subsequent follow-ups at 1, 4, 11, 15, 18, and 22 years of age and specific z scores were calculated by sex. The outcome was whole body aBMD (g/cm²) measured at 22 years of age using dual-energy X-ray absorptiometry (DXA). The effects of exposures, weight and length/height gain, were analyzed using conditional relative weight (CWh) and conditional length/height (CH). Linear regression models were adjusted for multiple confounders, including mother's educational level, family income, maternal smoking during pregnancy, gestational age, breastfeeding and skin color.

RESULTS

In the adjusted models, among men greater height gain at 4, 11, and 18 years of age was associated with higher whole body aBMD, and the result with greatest magnitude was at 11 years of age (β 0.018 g/cm²; 95%CI 0.006; 0.030). Among women, aBMD was associated with height gain at all assessments from 1-15 years, with greatest effect size at 4 years of age (β 0.017 g/cm²; 95%CI 0.007; 0.027). Regarding to body weight, among men, greater weight at 4 and 15 years were associated with higher aBMD, with the highest coefficients for 15 years of age (β 0.015 g/cm²; 95%CI 0.003; 0.027); for women, except at birth, all weight gain variables were associated with aBMD and the highest coefficients were observed at 4 years (β 0.025 g/cm²; 95%CI 0.015; 0.035).

CONCLUSIONS

In this birth cohort, height and weight gain, especially from 4 to 15 years have important positive implications for aBMD to early adulthood.

Bone Mass in Newborns Assessed by DXA - A Systematic Review and Meta-analysis

PURPOSE

Peak bone mass - a key determinant of osteoporotic fractures result from bone accretion starting form intrauterine life to early adulthood. Optimal skeletal growth in-utero and infancy may offer protection against osteoporosis in adult life. We attempted to pool the data from available literature to get a consensus on average bone mass among healthy newborns (age ≤30 days after birth).

METHODS

Systematic review was conducted (PRISMA guidelines) to generate pooled estimates of bone mass parameters at whole body (WB) and lumbar spine (LS), based on both fixed and random effect models of meta-analyses. Two investigators independently carried out a comprehensive literature search using PubMed, Google Scholar and Embase. Meta-regression was applied to further explore causes of heterogeneity.

RESULTS

Out of a total 2703 studies, 2682 was excluded leaving 21 studies for final analysis. Thirteen studies reported bone mass by Hologic^® and eight by Lunar^®. The pooled WBBMC was 66.2g (95% CI 65.4 to 67.05 by fixed effect model, while the corresponding parameter for LS was 2.3g (95% CI 2.2 to 2.4). The subgroup and meta-regression analyses done for controlling potential confounders did not significantly affect heterogeneity.

CONCLUSION

We generated the pooled estimate of bone mass (WBBMC) among healthy newborn subjects. There was high degree of heterogeneity among studies.

How Is Adolescent Bone Mass and Density Influenced by Early Life Body Size and Growth? The Tromsø Study: Fit Futures-A Longitudinal Cohort Study From Norway

The effect of birth weight and childhood body mass index (BMI) on adolescents’ bone parameters is not established. The aim of this longitudinal, population‐based study was to investigate the association of birth weight, childhood BMI, and growth, with adolescent bone mass and bone density in a sample of 633 adolescents (48% girls) from The Tromsø Study: Fit Futures. This population‐based cohort study was conducted in 2010–2011 and 2012–2013 in Tromsø, Norway. Bone mineral content (BMC) and areal BMD (aBMD) were measured at total hip (TH) and total body (TB) by dual‐energy X‐ray absorptiometry (DXA) and converted to internal Z‐scores. Birth weight and childhood anthropometric measurements were retrospectively obtained from the Medical Birth Registry of Norway and childhood health records. Associations between birth weight, BMI, and growth were evaluated by fitting linear mixed models with repeated measures of BMC and aBMD at ages 15 to 17 and 18 to 20 years as the outcome. In crude analysis, a significant positive association (p < 0.05) with TB BMC was observed per 1 SD score increase in birth weight, observed in both sexes. Higher rate of length growth, conditioned on earlier size, from birth to age 2.5 years, and higher rate of weight gain from ages 6.0 to 16.5 years, conditioned on earlier size and concurrent height growth, revealed stronger associations with bone accrual at ages 15 to 20 years compared with other ages. Compared with being normal weight, overweight/obesity at age 16.5 years was associated with higher aBMD Z‐scores: β coefficient (95% confidence interval [CI]) of 0.78 (0.53, 1.03) and 1.08 (0.85, 1.31) in girls, 0.63 (0.42, 0.85) and 0.74 (0.54, 0.95) in boys at TH and TB, respectively. Similar associations were found for BMC. Being underweight was consistently negatively associated with bone parameters in adolescence. In conclusion, birth weight influences adolescent bone mass but less than later growth and BMI in childhood and adolescence. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research

Ethnic Differences in Peripheral Skeletal Development Among Urban South African Adolescents: A Ten-Year Longitudinal pQCT Study

There are no longitudinal pQCT data of bone growth and development from sub-Saharan Africa, where rapid environmental, societal, and economic transitions are occurring, and where fracture rates are predicted to rise. The aim of this study was to compare skeletal development in black and white South African adolescents using longitudinal data from the Birth to Twenty study. The Birth to Twenty Bone Health subcohort consisted of 543 adolescents (261 [178 black] girls, 282 [201 black] boys). Annual pQCT measurements of the radial and tibial metaphysis and diaphysis were obtained between ages 12 and 22 years (distal metaphysis: cross-sectional area [CSA] and trabecular bone mineral density [BMD]; diaphysis: total and cortical CSA, cortical BMD, and polar stress-strain index [SSIp]). Age at peak height velocity (APHV) was calculated to account for differences in maturational timing between ethnic groups and sexes. Mixed-effects models were used to describe trajectories for each pQCT outcome. Likelihood-ratio tests were used to summarize the overall difference in trajectories between black and white participants within each sex. APHV (mean ± SD years) was similar in black (11.8 ± 0.8) and white (12.2 ± 1.0) girls, but delayed in black (14.2 ± 1.0) relative to white boys (13.3 ± 0.8). By 4 years post-APHV, white adolescents had significantly greater cortical CSA and SSIp than black adolescents at the radius. There were no significant differences at the radial metaphysis but there was some divergence, such that black adolescents had greater radial trabecular BMD by the end of follow-up. At the tibia, white adolescents had lower diaphyseal CSA and SSIp, and greater metaphyseal CSA. There was no ethnic difference in tibial trabecular BMD. There are ethnic differences in bone growth and development, independent of maturation, in South African adolescents. This work gives new insights into the possible etiology of childhood fractures, which occur most commonly as peripheral sites. © 2017 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Perinatal DNA Methylation at CDKN2A Is Associated With Offspring Bone Mass: Findings From the Southampton Women's Survey

Poor intrauterine and childhood growth has been linked with the risk of osteoporosis in later life, a relationship that may in part be mediated through altered epigenetic regulation of genes. We previously identified a region within the promoter of the long non-coding RNA ANRIL encoded by the CDKN2A locus, at which differential DNA methylation at birth showed correlations with offspring adiposity. Given the common lineage of adipocytes and osteoblasts, we investigated the relationship between perinatal CDKN2A methylation and bone mass at ages 4 and 6 years. Using sodium bisulfite pyrosequencing, we measured the methylation status of the 9 CpGs within this region in umbilical cord samples from discovery (n = 332) and replication (n = 337) cohorts of children from the Southampton Women's Survey, whose bone mass was assessed by dual-energy X-ray absorptiomietry (DXA; Hologic Discovery). Inverse associations were found between perinatal CDKN2A methylation and whole-body minus head bone area (BA), bone mineral content (BMC), and areal bone mineral density (BMD). This was confirmed in replication and combined data sets (all p < 0.01), with each 10% increase in methylation being associated with a decrease in BMC of 4 to 9 g at age 4 years (p ≤ 0.001). Relationships were similar with 6-year bone mass. Functional investigation of the differentially methylated region in the SaOS-2 osteosarcoma cell line showed that transcription factors bound to the identified CpGs in a methylation-specific manner and that CpG mutagenesis modulated ANRIL expression. In conclusion, perinatal methylation at CDKN2A is associated with childhood bone development and has significance for cell function. © 2017 American Society for Bone and Mineral Research.

Childhood growth predicts higher bone mass and greater bone area in early old age: findings among a subgroup of women from the Helsinki Birth Cohort Study

We examined the associations between childhood growth and bone properties among women at early old age. Early growth in height predicted greater bone area and higher bone mineral mass. However, information on growth did not improve prediction of bone properties beyond that predicted by body size at early old age.

INTRODUCTION

We examined the associations between body size at birth and childhood growth with bone area, bone mineral content (BMC), and areal bone mineral density (aBMD) in early old age.

METHODS

A subgroup of women (n = 178, mean 60.4 years) from the Helsinki Birth Cohort Study, born 1934-1944, participated in dual-energy X-ray absorptiometry (DXA) measurements of the lumbar spine and hip. Height and weight at 0, 2, 7, and 11 years, obtained from health care records, were reconstructed into conditional variables representing growth velocity independent of earlier growth. Weight was adjusted for corresponding height. Linear regression models were adjusted for multiple confounders.

RESULTS

Birth length and growth in height before 7 years of age were positively associated with femoral neck area (p < 0.05) and growth in height at all age periods studied with spine bone area (p < 0.01). Growth in height before the age of 7 years was associated with BMC in the femoral neck (p < 0.01) and birth length and growth in height before the age of 7 years were associated with BMC in the spine (p < 0.05). After entering adult height into the models, nearly all associations disappeared. Weight gain during childhood was not associated with bone area or BMC, and aBMD was not associated with early growth.

CONCLUSIONS

Optimal growth in height in girls is important for obtaining larger skeleton and consequently higher bone mass. However, when predicting bone mineral mass among elderly women, information on early growth does not improve prediction beyond that predicted by current height and weight.

Association of Body Size at Birth and Childhood Growth With Hip Fractures in Older Age: An Exploratory Follow-Up of the Helsinki Birth Cohort Study

Childhood growth has been linked with bone properties in adulthood, whereas less is known about the contribution of early growth to bone fracture risk. We investigated the association of body size at birth and childhood growth with hip fractures and pharmacotherapy for osteoporosis in older age. Men and women, born full term, from the Helsinki Birth Cohort Study (n = 8345) were followed until the age of 68 to 80 years. Height and weight from birth to 11 years were obtained from health care records and diagnoses of hip fractures and osteoporosis drug purchases from national registers. Independent associations of each age period were analyzed using Cox models adjusted for age, childhood and adulthood socioeconomic status, and drugs affecting bone metabolism. In men, the risk of hip fractures was nonlinearly associated with childhood growth. Compared to intermediate increase, low and high increase in height between 2 and 7 years (p < 0.001) were associated with all hip fractures and hip fractures sustained after the age of 50 years. Further, compared to intermediate gain, low and high gain in BMI between 7 and 11 years (p = 0.001) were associated with greater risk of hip fractures in men. In women, growth was not associated with the risk of hip fractures but greater weight (hazard ratio [HR] = 0.85; 95% CI, 0.77 to 0.94; p = 0.001) and BMI (HR 0.86; 95% CI, 0.78 to 0.95; p = 0.003) gain between ages 2 and 7 years were associated with a decreased risk of pharmacotherapy for osteoporosis. In men, growth was not associated with the risk of pharmacotherapy for osteoporosis. In conclusion, growth during childhood may contribute to the risk of hip fractures in later life among men. © 2017 American Society for Bone and Mineral Research.

Secular trends in fracture incidence in the UK between 1990 and 2012

We studied sex-specific incidence rates in a population 50 years or older in the UK. In the period of 1990-2012, the overall rate of fracture did not change, but there were marked secular alterations in the rates of individual fracture types, particularly hip and spine fractures in the elderly.

INTRODUCTION

There is increasing evidence of secular changes in age- and sex- adjusted fracture incidence globally. Such observations broadly suggest decreasing rates in developed countries and increasing rates in transitioning populations. Since altered fracture rates have major implications for healthcare provision and planning, we investigated secular changes to age- and sex-adjusted fracture risk amongst the UK population aged 50 years or above from 1990 till 2012.

METHODS

We undertook a retrospective observational study using the Clinical Practice Research Datalink (CPRD), which contains the health records of 6.9 % of the UK population. Site-specific fracture incidence was calculated by calendar year for men and women separately, with fracture type categorised according to ICD-9 classification. Linear regression analysis was used to calculate mean annualised change in absolute incidence. For presentational purposes, mean rates in the first 5 years and last 5 years of the period were calculated.

RESULTS

Overall fracture incidence was unchanged in both women and men from 1990 to 2012. The incidence of hip fracture remained stable amongst women (1990-1994 33.8 per 10,000 py; 2008-2012 33.5 per 10,000 py; p trend annualised change in incidence = 0.80) but rose in men across the same period (10.8 to 13.4 per 10,000 py; p = 0.002). Clinical vertebral fractures became more common in women (8.9 to 11.8 per 10,000 py; p = 0.005) but remained comparable in men (4.6 to 5.9 per 10,000 py; p = 0.72). Similarly, the frequency of radius/ulna fractures did not change in men (9.6 to 9.6 per 10,000 py; p = 0.25), but, in contrast, became less frequent in women (50.4 to 41.2 per 10,000 py; p = 0.001). Secular trends amongst fractures of the carpus, scapula, humerus, foot, pelvis, skull, clavicle, ankle, patella, and ribs varied according to fracture site and sex.

CONCLUSION

Although overall sex-specific fracture incidence in the UK population 50 years or over appears to have remained stable over the last two decades, there have been noticeable changes in rates of individual fracture types. Given that the impact of a fracture on morbidity, mortality, and health economy varies according to fracture site, these data inform the provision of healthcare services in the UK and elsewhere.

Placental Size Is Associated Differentially With Postnatal Bone Size and Density

We investigated relationships between placental size and offspring adolescent bone indices using a population-based, mother-offspring cohort. The Avon Longitudinal Study of Parents and Children (ALSPAC) recruited pregnant women from the southwest of England between 1991 and 1993. There were 12,942 singleton babies born at term who survived at least the first 12 months. From these, 8933 placentas were preserved in formaldehyde, with maternal permission for their use in research studies. At the approximate age of 15.5 years, the children underwent a dual-energy X-ray absorptiometry (DXA) scan (measurements taken of the whole body minus head bone area [BA], bone mineral content [BMC], and areal bone mineral density [aBMD]). A peripheral quantitative computed tomography (pQCT) scan (Stratec XCT2000L; Stratec, Pforzheim, Germany) at the 50% tibial site was performed at this visit and at approximately age 17.7 years. In 2010 a sample of 1680 placentas were measured and photographed. To enable comparison of effect size across different variables, predictor and outcome variables were standardized to Z-scores and therefore results may be interpreted as partial correlation coefficients. Complete placental, DXA, and pQCT data were available for 518 children at age 15.5 years. After adjustment for gender, gestational age at birth, and age at time of pQCT, the placental area was positively associated with endosteal circumference (β [95% CI]: 0.21 [0.13, 0.30], p < 0.001), periosteal circumference (β [95% CI]: 0.19 [0.10, 0.27], p < 0.001), and cortical area (β [95% CI]: 0.10 [0.01, 0.18], p = 0.03), and was negatively associated with cortical density (β [95% CI]: -0.11 [-0.20, -0.03], p = 0.01) at age 15.5 years. Similar relationships were observed for placental volume, and after adjustment for additional maternal and offspring covariates. These results suggest that previously observed associations between placental size and offspring bone development persist into older childhood, even during puberty, and that placental size is differentially related to bone size and volumetric density. © 2016 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

Regulation of osteoblast development by Bcl-2-associated athanogene-1 (BAG-1)

BCL-2-associated athanogene-1 (BAG-1) is expressed by osteoblast-lineage cells; early embryonic lethality in Bag-1 null mice, however, has limited the investigation of BAG-1 function in osteoblast development. In the present study, bone morphogenetic protein-2/BMP-2-directed osteogenic differentiation of bone marrow stromal cells (BMSCs) of Bag-1^+/− (heterozygous) female mice was decreased significantly. Genes crucial for osteogenic differentiation, bone matrix formation and mineralisation were expressed at significantly lower levels in cultures of Bag-1^+/− BMSCs supplemented with BMP-2, while genes with roles in inhibition of BMP-2-directed osteoblastogenesis were significantly upregulated. 17-β-estradiol (E2) enhanced responsiveness of BMSCs of wild-type and Bag-1^+/− mice to BMP-2, and promoted robust BMP-2-stimulated osteogenic differentiation of BMSCs. BAG-1 can modulate cellular responses to E2 by regulating the establishment of functional estrogen receptors (ERs), crucially, via its interaction with heat shock proteins (HSC70/HSP70). Inhibition of BAG-1 binding to HSC70 by the small-molecule chemical inhibitor, Thioflavin-S, and a short peptide derived from the C-terminal BAG domain, which mediates binding with the ATPase domain of HSC70, resulted in significant downregulation of E2/ER-facilitated BMP-2-directed osteogenic differentiation of BMSCs. These studies demonstrate for the first time the significance of BAG-1-mediated protein-protein interactions, specifically, BAG-1-regulated activation of ER by HSC70, in modulation of E2-facilitated BMP-2-directed osteoblast development.

Pubertal timing and bone phenotype in early old age: findings from a British birth cohort study

Objectives: To investigate the effect of pubertal timing, assessed in adolescence, on bone size, strength and density in men and women in early old age.

Design: A British birth cohort study with prospective indicators of pubertal timing based on age at menarche, clinical assessment of pubertal stage, and growth tempo from serial height measures, and bone measures derived from peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA) at 60-64 years of age among 866 women and 792 men.

Methods: A first set of regression models investigated the relationships between pubertal timing and bone size, strength and density, adjusting for current height and weight, smoking and adult socioeconomic position. To make an equivalent comparison between men and women, the percentage difference in bone outcomes was calculated for a 5-year difference in age at menarche, and in men a comparison between those who were fully mature or pre-adolescent at 14.5 years. A second set of models investigated the percentage difference in bone outcomes for a 5-year difference in timing of peak height velocity (height tempo) derived from longitudinal growth modelling (Superimposition by Translation and Rotation model; SITAR).

Results: After adjustment for current height and weight, a 5-year increase in age at menarche was associated with an 8% [95% confidence interval (CI) -17%, 0.5%, P = 0.07) lower trabecular volumetric bone mineral density (vBMD); men who were pre-adolescent at 14.5 years had a 9%, (95% CI -14%, -4%; P = 0.001) lower trabecular vBMD compared with those who had been fully mature. Other confounders did not attenuate these estimates further. Patterns of association were similar but somewhat weaker for lumbar spine and total hip areal BMD. Age at peak height velocity was associated with even larger differences in BMD in men and women, and was negatively associated with bone size and strength.

Conclusions: The association between later puberty and lower BMD persists into early old age. The 9-10% lower trabecular vBMD in later compared with earlier maturers could be clinically important given a rate of bone loss from midlife of 1-2% a year and the negative association between BMD and fracture.

Life-course approach to nutrition

This narrative review summarizes the role that nutrition plays in the development and maintenance of a healthy skeleton throughout the life-course. Nutrition has a significant influence on bone health throughout the life cycle. This narrative review summarizes current knowledge and guidance pertaining to the development and maintenance of a healthy skeleton. The primary objectives proposed for good bone health at the various stages of life are the following: Children and adolescents: achieve genetic potential for peak bone mass Adults: avoid premature bone loss and maintain a healthy skeleton Seniors: prevention and treatment of osteoporosis Findings from cohort studies, randomized controlled trials, systematic reviews and meta-analyses, in addition to current dietary guidelines, are summarized with the intention of providing clear nutritional guidance for these populations and pregnant women.

Early Trabecular Development in Human Vertebrae: Overproduction, Constructive Regression, and Refinement

Early bone development may have a significant impact upon bone health in adulthood. Bone mineral density (BMD) and bone mass are important determinants of adult bone strength. However, several studies have shown that BMD and bone mass decrease after birth. If early development is important for strength, why does this reduction occur? To investigate this, more data characterizing gestational, infant, and childhood bone development are needed in order to compare with adults. The aim of this study is to document early vertebral trabecular bone development, a key fragility fracture site, and infer whether this period is important for adult bone mass and structure. A series of 120 vertebrae aged between 6 months gestation and 2.5 years were visualized using microcomputed tomography. Spherical volumes of interest were defined, thresholded, and measured using 3D bone analysis software (BoneJ, Quant3D). The findings showed that gestation was characterized by increasing bone volume fraction whilst infancy was defined by significant bone loss (≈2/3rds) and the appearance of a highly anisotropic trabecular structure with a predominantly inferior-superior direction. Childhood development progressed via selective thickening of some trabeculae and the loss of others; maintaining bone volume whilst creating a more anisotropic structure. Overall, the pattern of vertebral development is one of gestational overproduction followed by infant "sculpting" of bone tissue during the first year of life (perhaps in order to regulate mineral homeostasis or to adapt to loading environment) and then subsequent refinement during early childhood. Comparison of early bone developmental data in this study with adult bone volume values taken from the literature shows that the loss in bone mass that occurs during the first year of life is never fully recovered. Early development could therefore be important for developing bone strength, but through structural changes in trabecular microarchitecture rather than bone mass.

Pubertal timing, bone acquisition, and risk of fracture throughout life

Pubertal maturation plays a fundamental role in bone acquisition. In retrospective epidemiological surveys in pre- and postmenopausal women, relatively later menarcheal age was associated with low bone mineral mass and increased risk of osteoporotic fracture. This association was usually ascribed to shorter time exposure to estrogen from the onset of pubertal maturation to peak bone mass attainment. Recent prospective studies in healthy children and adolescents do not corroborate the limited estrogen exposure hypothesis. In prepubertal girls who will experience later menarche, a reduced bone mineral density was observed before the onset of pubertal maturation, with no further accumulated deficit until peak bone mass attainment. In young adulthood, later menarche is associated with impaired microstructural bone components and reduced mechanical resistance. This intrinsic bone deficit can explain the fact that later menarche increases fracture risk during childhood and adolescence. In healthy individuals, both pubertal timing and bone development share several similar characteristics including wide physiological variability and strong effect of heritable factors but moderate influence of environmental determinants such as nutrition and physical activity. Several conditions modify pubertal timing and bone acquisition, a certain number of them acting in concert on both traits. Taken together, these facts should prompt the search for common genetic regulators of pubertal timing and bone acquisition. It should also open epigenetic investigation avenues to pinpoint which environmental exposure in fetal and infancy life, such as vitamin D, calcium, and/or protein supplies, influences both pubertal timing and bone acquisition.

Birth weight is not associated with risk of fracture: results from two Swedish cohort studies

Development and growth in utero has been suggested to influence bone health. However, the relationship with risk of fracture in old age is largely unknown. Using Cox proportional hazards regression, we studied the association between birth weight and fractures at ages 50-94 among 10,893 men and women (48% women) from the Uppsala Birth Cohort Study (UBCoS, born 1915-29) and 1334 men from the Uppsala Longitudinal Study of Adult Men (ULSAM, born 1920-24). Measured birth weight was collected from hospital or midwives' records and fractures from the Swedish National Patient Register. We observed 2796 fractures (717 of these were hip fractures) in UBCoS and 335 fractures (102 hip fractures) in ULSAM. In UBCoS, the hazard ratio (HR) per 1 kg increase in birth weight, adjusted for sex and socioeconomic status at birth, was 1.01 [95% confidence interval (CI), 0.94-1.09] for any fracture and 1.06 (95% CI, 0.91-1.23) for hip fracture. Estimates in ULSAM were similar. We did not observe a differential association of birth weight with fractures occurring before age 70 or after age 70 years. Neither birth weight standardized for gestational age nor gestational duration was associated with fracture rate. In linear regression, birth weight was not associated with bone mineral density among 303 men who were 82-years-old in ULSAM but showed positive associations with total body bone mineral content (β per kg increase in birth weight, adjusted for social class and age, 133; 95% CI, 30-227). This association was attenuated after further adjustment for body mass index and height (β, 41; 95% CI, -43-126). We conclude that birth weight is associated with bone mineral content but this association does not translate into an association with risk of fracture in men and women aged 50-94 years.

Osteoporosis: a lifecourse approach

It is becoming increasingly apparent that the risk of developing osteoporosis is accrued throughout the entire lifecourse, even from as early as conception. Thus early growth is associated with bone mass at peak and in older age, and risk of hip fracture. Novel findings from mother-offspring cohorts have yielded greater understanding of relationships between patterns of intrauterine and postnatal growth in the context of later bone development. Study of biological samples from these populations has helped characterize potential mechanistic underpinnings, such as epigenetic processes. Global policy has recognized the importance of early growth and nutrition to the risk of developing adult chronic noncommunicable diseases such as osteoporosis; testing of pregnancy interventions aimed at optimizing offspring bone health is now underway. It is hoped that through such programs, novel public health strategies may be established with the ultimate goal of reducing the burden of osteoporotic fracture in older age.

Birth weight is positively related to bone size in adolescents but inversely related to cortical bone mineral density: findings from a large prospective cohort study

To examine the influence of intrauterine environment on subsequent bone development, we investigated the relationship between birth weight and cortical bone parameters, and the role of puberty, bone resorption and insulin as possible mediators. Bone outcomes were obtained from mid-tibial pQCT scans performed at age 15.5 years in 1960 males and 2192 females from the ALSPAC birth cohort. Birth weight was positively related to periosteal circumference (PC) [beta=0.40 (0.34, 0.46)], which was largely but not completely attenuated after adjustment for height and weight [beta=0.07 (0.02, 0.12)] (SD change in outcome per 1 kg increase in birth weight with 95% CI). Based on our height and weight adjusted model, the association was stronger in females compared to males (P=0.02 for gender interaction), and persisted in 2842 participants with equivalent results at age 17.7 years. Conversely, birth weight was inversely related to cortical bone mineral density (BMDC) at age 15.5 years after adjusting for height and weight [beta=-0.18 (-0.23, -0.13)], with a stronger association in males compared to females (P=0.01 for gender interaction), but an equivalent association was not seen at 17.7 years. In further analyses performed on data from age 15.5 years, the association between birth weight and PC was unaffected by adjustment for puberty (Tanner stage at age 13.5 years), bone resorption (fasting beta-carboxyterminal cross linking telopeptide (βCTX) at age 15.5 years) or insulin (fasting insulin at age 15.5 years). In contrast, the association with BMDC was attenuated by approximately 30% after adjustment for puberty or bone resorption, and by 50% after adjustment for both factors combined. We conclude that the inverse relationship between birth weight and BMDC is in part mediated by effects of puberty and bone resorption, which may help to explain the transitory nature of this association, in contrast to the more persisting relationship with PC.

The Tromsø Study: Fit Futures: a study of Norwegian adolescents' lifestyle and bone health

Bone mass achievement predicts later fracture risk. This population-based study describes bone mineral density (BMD) levels and associated factors in Norwegian adolescents. Compared with international reference ranges, BMD levels appear higher and physical activity levels are positively associated with BMD.

PURPOSE

Norway has one of the highest reported incidences of osteoporotic fractures. Maximisation of peak bone mass may prevent later fractures. This population-based study compared BMD levels of Norwegian adolescents with international reference ranges and explored associated factors.

METHODS

All first-year upper-secondary school students, aged 15-19 years in the Tromsø region were invited to the Fit Futures study in 2010-2011. Over 90 % of the invited participants attended, 508 girls and 530 boys. BMD was measured at total hip, femoral neck and total body by dual X-ray absorptiometry. Lifestyle variables were collected by self-administered questionnaires and interviews. All analyses were performed sex stratified, using linear regression models.

RESULTS

In girls, mean BMD (SD) was 1.060 g/cm(2) (0.124), 1.066 g/cm(2) (0.123) and 1.142 g/cm(2) (0.077) at the total hip, femoral neck and total body, respectively. In boys, corresponding values were 1.116 (0.147), 1.103 (0.150) and 1.182 (0.097), with significant higher values than the Lunar pediatric reference at 16 years of age. In girls, height and self-reported intensive physical activity of more than 4 h a week and early sexual maturation were positively associated with BMD at both femoral sites (p < 0.047). Among boys age, height, body mass index, physical activity and alcohol intake were positively (p < 0.038), whereas early stages of sexual maturation and smoking was negatively (p < 0.047) related to BMD.

CONCLUSIONS

Despite the heavy fracture burden, Norwegian adolescents' BMD levels are higher than age-matched Caucasians. Physical activity is associated with 1 SD increased BMD levels in those involved in competition or hard training.

Childhood bone mineral content is associated with methylation status of the RXRA promoter at birth

Maternal vitamin D deficiency has been associated with reduced offspring bone mineral accrual. Retinoid-X receptor-alpha (RXRA) is an essential cofactor in the action of 1,25-dihydroxyvitamin D (1,25[OH]2 -vitamin D), and RXRA methylation in umbilical cord DNA has been associated with later offspring adiposity. We tested the hypothesis that RXRA methylation in umbilical cord DNA collected at birth is associated with offspring skeletal development, assessed by dual-energy X-ray absorptiometry, in a population-based mother-offspring cohort (Southampton Women's Survey). Relationships between maternal plasma 25-hydroxyvitamin D (25[OH]-vitamin D) concentrations and cord RXRA methylation were also investigated. In 230 children aged 4 years, a higher percent methylation at four of six RXRA CpG sites measured was correlated with lower offspring bone mineral content (BMC) corrected for body size (β = -2.1 to -3.4 g/SD, p = 0.002 to 0.047). In a second independent cohort (n = 64), similar negative associations at two of these CpG sites, but positive associations at the two remaining sites, were observed; however, none of the relationships in this replication cohort achieved statistical significance. The maternal free 25(OH)-vitamin D index was negatively associated with methylation at one of these RXRA CpG sites (β = -3.3 SD/unit, p = 0.03). Thus, perinatal epigenetic marking at the RXRA promoter region in umbilical cord was inversely associated with offspring size-corrected BMC in childhood. The potential mechanistic and functional significance of this finding remains a subject for further investigation.

Fracture patterns and bone mass in South African adolescent-mother pairs: the Birth to Twenty cohort

The associations of fracture prevalence and bone mass in adolescents with maternal fracture history and bone mass have not been investigated previously in South Africa. Maternal bone mass has a significant inverse association with their adolescents' fracture rates and bone mass across all ethnic groups.

INTRODUCTION

Differences in fracture rates and bone mass between families and individuals of different ethnic origins may be due to differing lifestyles and/or genetic backgrounds. This study aimed to assess associations of fracture prevalence and bone mass in adolescents with maternal fracture history and bone mass, and sibling fracture history.

METHODS

Data from 1,389 adolescent-biological mother pairs from the Birth to Twenty longitudinal study were obtained. Questionnaires were completed on adolescent fractures until 17/18 years of age and on sibling fractures. Biological mothers completed questionnaires on their own fractures prior to the age of 18 years. Anthropometric and bone mass data on adolescent-biological mother pairs were collected.

RESULTS

An adolescent's risk of lifetime fracture decreased with increasing maternal lumbar spine (LS) bone mineral content (BMC; 24 % reduction in fracture risk for every unit increase in maternal LS BMC Z-score) and increased if they were white, male, or had a sibling with a history of fracture. Adolescent height, weight, male gender, maternal bone area and BMC, and white ethnicity were positive predictors of adolescent bone mass. White adolescents and their mothers had a higher fracture prevalence (adolescents 42 %, mothers 31 %) compared to the black (adolescents 20 %, mothers 6 %) and mixed ancestry (adolescents 20 %, mothers 16 %) groups.

CONCLUSION

Maternal bone mass has a significant inverse association with their adolescent off-springs' fracture risk and bone mass. Furthermore, there is a strong familial component in fracture patterns among South African adolescents and their siblings.

Growth from birth to adulthood and bone phenotype in early old age: a British birth cohort study

There is growing evidence that early growth influences bone mass in later life but most studies are limited to birth weight and/or early infant growth and dual-energy X-ray absorptiometry (DXA) measurements. In a British birth cohort study with prospective measures of lifetime height and weight, we investigated the growth trajectory in relation to bone in males (M) and females (F) at 60 to 64 years old. Outcomes were DXA measures of hip and spine areal bone density (aBMD) (n = 1658) and pQCT measures of distal and diaphyseal radius cross-sectional area (CSA), strength, and volumetric bone density (vBMD) (n = 1350 of the 1658). Regression models examined percentage change in bone parameters with standardized measures of birth weight, height, and weight. A series of conditional growth models were fitted for height and weight gain (using intervals: birth-2, 2-4, 4-7, 7-15, 15-20, 20-36, and 36-64 years) and height gain (using intervals: 2-4, 4-7, 7-15, and 15-36 years). Birth weight was positively related to bone CSA (M: 1.4%; 95% confidence interval [CI], 0.3%-2.5%; F: 1.3%; 95% CI, 0.3%-2.4% per 1 SD increase in birth weight for diaphyseal CSA) and strength (M: 1.8%; 95% CI, 0.3-3.4; F: 2.0%; 95% CI, 0.5-3.5). No positive associations were found with trabecular, total, or cortical vBMD. One SD change in prepubertal and postpubertal height and weight velocities were associated with between 2% and 5% greater bone CSA and strength. Height gain in later years was negatively associated with trabecular vBMD. Weight gain velocity during the adult years was positively associated with up to 4% greater trabecular and total BMD, and 4% greater aBMD at hip and spine. In a cohort born in the early post-war period, higher birth weight, gaining weight and height faster than others, particularly through the prepubertal and postpubertal periods, was positively related to bone strength, mostly through greater bone CSA, at 60 to 64 years.

Birth weight and adult bone metabolism are unrelated: results from birth weight-discordant monozygotic twins

Low birth weight (BW) has been associated with poor bone health in adulthood. The aim of this study was to investigate the association between BW and bone mass and metabolism in adult BW-discordant monozygotic (MZ) twins. A total of 153 BW-extremely discordant MZ twin pairs were recruited from the Danish Twin Registry. Serum vitamin D (25-hydroxyvitamin D [25OHD]) and bone turnover markers (BTMs) amino-terminal propeptide of type I procollagen (P1NP), pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (1CTP), and cross-linked C-telopeptide (CTX) were quantified. Femoral neck (FN), total hip (TH), lumbar spine (LS), and whole-body (WB) bone mineral density (BMD) (ie, FN-BMD, TH-BMD, LS-BMD, and WB-BMD, respectively) were measured using dual-energy X-ray absorptiometry (DXA). Twins were studied as single individuals using regression analyses with or without adjustment for height, weight, age, sex, and intrapair correlation. Within-pair differences were assessed using Student's t test and fixed-regression models. BW was not associated with BTMs, LS-BMD, TH-BMD, FN-BMD, or WB-BMD, but BW was associated with WB-BMC, and WB-Area after adjustments. Compared to the co-twin, twins with the highest BW were heavier and taller in adulthood (mean differences ± SD): 3.0 ± 10.5 kg; 1.6 ± 2.6 cm; both p < 0.001). Within-pair analyses showed that LS-BMD, TH-BMD, and FN-BMD tended to be higher in twins with highest BW (for all: mean difference 0.01 ± 0.1 g/cm(2) ; p = 0.08, 0.05, and 0.10, respectively). No difference was observed after adjustment for adult body size. Intrapair differences in BW were not associated with differences in any of the biochemical parameters or BMD. Small differences between twins in BMD were explained by dissimilarities in body size. These results suggest that BW and adult bone metabolism are unrelated.

Fetal and infant growth predict hip geometry at 6 y old: findings from the Southampton Women's Survey

BACKGROUND

We investigated relationships between early growth and proximal femoral geometry at age 6 y in a prospective population-based cohort, the Southampton Women's Survey.

METHODS

In 493 mother-offspring pairs, we assessed linear size using high-resolution ultrasound at 11, 19, and 34 wk gestation (femur length) and at birth and 1, 2, 3, 4, and 6 y (crown-heel length/height). SD scores were created and conditional regression modeling generated mutually independent growth variables. Children underwent hip dual-energy X-ray absorptiometry (DXA) at 6 y; hip structure analysis software yielded measures of geometry and strength.

RESULTS

There were strong associations between early linear growth and femoral neck section modulus (Z) at 6 y, with the strongest relationships observed for femur growth from 19 to 34 wk gestation (β = 0.26 cm(3)/SD, P < 0.0001), and for height growth from birth to 1 y (β = 0.25 cm(3)/SD, P < 0.0001) and 1 to 2 y (β = 0.33 cm(3)/SD, P < 0.0001), with progressively weaker relationships over years 3 (β = 0.23 cm(3)/SD, P = 0.0002) and 4 (β = 0.10 cm(3)/SD, P = 0.18).

CONCLUSION

These results demonstrate that growth before age 3 y predicts proximal femoral geometry at 6 y old. These data suggest critical periods in which there is capacity for long-term influence on the later skeletal growth trajectory.

Programming of osteoporosis and impact on osteoporosis risk

Osteoporosis is a skeletal disorder characterized by reduced bone quantity and quality and an increased susceptibility to fracture, and seems to be one of many chronic conditions that might be influenced by events early in life. Specifically, there is growing evidence of an interaction between the genome and the environment in the expression of the disease.

Growth from birth to adulthood and peak bone mass and density data from the New Delhi Birth Cohort

Growth in early life may predict adult bone health. Our data showed that greater height and body mass index (BMI) gain in utero and infancy are associated with higher peak bone mass, and greater BMI gain in childhood/adolescence with higher peak bone density. These associations are mediated by attained adult height and BMI.

INTRODUCTION

To study the relationship of height and BMI during childhood with adult bone mineral content (BMC), areal density (aBMD) and apparent density (BMAD, estimated volumetric density).

METHODS

Participants comprised 565 men and women aged 33-39 years from the New Delhi Birth Cohort, India, whose weight and height were recorded at birth and annually during infancy (0-2 years), childhood (2-11 years) and adolescence (11 years-adult). Lumbar spine, femoral neck and forearm BMC and aBMD were measured using dual X-ray absorptiometry; lumbar spine and femoral neck BMAD were calculated.

RESULTS

Birth length, and height and height gain during infancy, childhood and adolescence were positively correlated with adult BMC (p≤0.01 all sites except birth length with femoral neck). Correlations increased with height from birth to 6 years, then remained constant for later height measurements. There were no associations with BMAD. BMI at birth, and during childhood and adolescence was also positively correlated with BMC (p < 0.01 all sites). BMI at 11 years, and BMI gain in childhood and adolescence, were correlated with aBMD and BMAD (p < 0.001 for all); these correlations strengthened with increasing age of BMI measurement. The associations with height and BMI in early life became non-significant after adjustment for adult height and BMI.

CONCLUSIONS

Greater skeletal growth and BMI gain in utero and during infancy are associated with higher peak BMC, and greater BMI gain in childhood and adolescence is associated with higher peak aBMD and BMAD. These associations are mediated by the attainment of adult height and BMI, respectively.

Using cohort studies in lifecourse epidemiology

The UK Medical Research Council (MRC) Population Health Sciences Research Network is a network of MRC research units and centres that aims to bring together and add value to existing MRC investment in public health, health services and epidemiological research. This symposium held in August 2011 at the World Congress of Epidemiology, Edinburgh, discussed a range of topics including methodology and analytical issues based on a number of examples of cohort studies within the context of lifecourse epidemiology.

Season of birth and the risk of hip fracture in danish men and women aged 65+

Vitamin D status in pregnant women has been linked to childhood bone mineral density in their offspring but it is unclear if effects extend to fracture risk in adulthood or even old age. As vitamin D levels in the population show pronounced seasonal variation in Denmark, we performed an epidemiological analysis of hip fracture rates as a function of season of birth, age, and sex. We retrieved information on all hip fractures in the 9-year period between 1997 and 2005 in all men and women aged 65-95, excluded hip fractures that occurred in current and recent prednisolone users, and subsequently calculated fracture rates and relative risks. The analysis covered 541,109 men and 691,522 women. In women, we observed a small but statistically significant difference between fracture rates by season of birth for all age intervals expect the youngest (age 65-69). A similar pattern was seen in men, but this was only statistically significant in the two oldest age groups (age 85-89 and 90-95). These findings suggest that vitamin D availability in the first and second trimester of intrauterine life could have a small but lasting impact on bone health and the risk of osteoporotic fractures. Further studies are needed.

Epidemiology of bone fracture across the age span in blacks and whites

BACKGROUND

Gender and racial disparities in injury mortality have been well established, but less is known regarding differences in fracture-related hospitalizations across the age span.

METHODS

Cross-sectional analysis of annual incident fracture hospital admissions used statewide acute care hospital discharge data (Statewide Program and Research Cooperative System) for non-Hispanic White (n = 138,763) and non-Hispanic Black (n = 19,588) residents of New York State between 2000 and 2002. US census data with intercensal estimates were used to ascertain the population at risk. Gender- and race-specific incident fracture was calculated in 5-year age intervals. The χ test was used to analyze categorical variables.

RESULTS

Mechanisms of injury vary by race and gender in their relative contribution to injury-related fractures across the age span. Black males exhibited higher fracture incidence until approximately age 62, while incidence in women diverged around age 45. Total motor vehicle traffic-related fracture hospitalization is bimodal in Whites but not in Blacks. Over the life span, all groups exhibited bimodal pedestrian fractures with pedestrian fractures accounting for 8.8% and 2.5% of all fractures in Blacks and Whites, respectively. Racial disparities were present from preschool through age 70. Violence-related fractures were 10 times higher in Blacks, accounting for 18.2% of hospitalizations. Black males exhibit higher fracture incidence due to violence by age 5 and higher gun violence by age 10; both remain elevated through age 75.

CONCLUSIONS

Despite historical studies demonstrating higher bone density in Blacks, this study found racial disparities with increased fracture risk in both Black children and adults across most nonfall-related injury mechanisms examined.

Pubertal timing and body mass index gain from birth to maturity in relation with femoral neck BMD and distal tibia microstructure in healthy female subjects

Childhood body mass index (BMI) gain is linked to hip fracture risk in elderly. In healthy girls, menarcheal age is inversely related to BMI gain during childhood and to femoral neck areal bone mass density (aBMD) and distal tibia structural components at maturity. This study underscores the importance of pubertal timing in age-related fragility fracture risk.

INTRODUCTION

Recent data point to a relationship between BMI change during childhood and hip fracture risk in later life. We hypothesized that BMI development is linked to variation in pubertal timing as assessed by menarcheal age (MENA) which in turn, is related to peak bone mass (PBM) and hip fracture risk in elderly.

METHODS

We studied in a 124 healthy female cohort the relationship between MENA and BMI from birth to maturity, and DXA-measured femoral neck (FN) aBMD at 20.4 year. At this age, we also measured bone strength related microstructure components of distal tibia by HR-pQCT.

RESULTS

At 20.4 ± 0.6 year, FN aBMD (mg/cm(2)), cortical thickness (μm), and trabecular density (mg HA/cm(3)) of distal tibia were inversely related to MENA (P = 0.023, 0.015, and 0.041, respectively) and positively to BMI changes from 1.0 to 12.4 years (P = 0.031, 0.089, 0.016, respectively). Significant inverse (P < 0.022 to <0.001) correlations (R = -0.21 to -0.42) were found between MENA and BMI from 7.9 to 20.4 years, but neither at birth nor at 1.0 year. Linear regression indicated that MENA Z-score was inversely related to BMI changes not only from 1.0 to 12.4 years (R = -0.35, P = 0.001), but also from 1.0 to 8.9 years, (R = -0.24, P = 0.017), i.e., before pubertal maturation.

CONCLUSION

BMI gain during childhood is associated with pubertal timing, which in turn, is correlated with several bone traits measured at PBM including FN aBMD, cortical thickness, and volumetric trabecular density of distal tibia. These data complement the reported relationship between childhood BMI gain and hip fracture risk in later life.

Low birth weight, bone metabolism and fracture risk

As for other diseases of higher age, low birth weight was expected to be a risk factor for an altered bone metabolism and osteoporosis.ON THE FIRST GLANCE THIS EXPECTATION APPEARS TO BE CONFIRMED BY ANIMAL DATA: rats with intrauterine growth restriction following maternal protein malnutrition show a reduction of bone mineral density going in line with a decrease in serum vitamin D concentrations.HOWEVER, THE SITUATION IS LESS CLEAR IN NEWBORNS WITH LOW BIRTH WEIGHT: Some studies show a relation of birth weight and bone mineral density whereas others don't. The older the former low birth weight patients the fainter the effect seems to be. In fact young adults with idiopathic short stature have a low bone mineral density than the low birth weight group irrespective of whether they have experienced catch-up growth or not. As a consequence low birth weight is can not be identified as a relevant risk factor for hip fractures in menopausal women. Postmenopausal women with low birth weight even show higher vitamin D concentrations than normal birth weight individuals.In conclusion, there is no consistent long term effect of low birth weight on bone mineral density or hip fracture risk later in life. Whether methodological weaknesses in the studies performed so far are causal or whether postnatal factors such as physical activity and nutrition are of higher importance can only be speculated upon at present.

Self-reported weight at birth predicts measures of femoral size but not volumetric BMD in eldery men: MrOS

The mechanism whereby poor intrauterine growth increases risk of adult hip fracture is unclear. We report the association between birth weight and proximal femoral geometry and density in community-dwelling elderly men. We used self-reported birth weight, measured adult height and weight and proximal femoral quantitative computed tomography (QCT) measurements of femoral neck axis length, cross-sectional area, and volumetric BMD (vBMD) among the participants in the Osteoporotic Fractures in Men (MrOS), a cohort study of community-dwelling US men aged 65 and older. We compared men with birth weight <7 pounds (lower birth weight [LBW]; n = 501) and ≥ 9 pounds (higher birth weight [HBW]; n = 262) with those weighing 7-8.9 pounds (medium birth weight [MBW], referent group; n = 1068) using linear regression adjusting for current age, height, and BMI. The mean age of the 1831 men who had both birth weight and QCT measurements was 73 years (SD 5.9). Compared with the referent MBW, HBW men had concordantly longer femoral neck (+0.16 SD; p = .028) and cross-sectional area (+0.24 SD, p = .001). LBW men had a smaller cross-sectional (-0.26 SD, p < .001) but longer femoral neck for their height (+0.11 SD, p = .05). Neither cortical nor trabecular vBMD at the femoral neck was associated with birth weight. These findings support the hypothesis that the skeletal envelope, but not density, is set, in part, at birth. Further research exploring the association between early developmental factors and lifetime fracture risk is needed and may inform primary preventative strategies for fracture prevention.

Fetal origins of adult disease

Dr. David Barker first popularized the concept of fetal origins of adult disease (FOAD). Since its inception, FOAD has received considerable attention. The FOAD hypothesis holds that events during early development have a profound impact on one's risk for development of future adult disease. Low birth weight, a surrogate marker of poor fetal growth and nutrition, is linked to coronary artery disease, hypertension, obesity, and insulin resistance. Clues originally arose from large 20th century, European birth registries. Today, large, diverse human cohorts and various animal models have extensively replicated these original observations. This review focuses on the pathogenesis related to FOAD and examines Dr. David Barker's landmark studies, along with additional human and animal model data. Implications of the FOAD extend beyond the low birth weight population and include babies exposed to stress, both nutritional and nonnutritional, during different critical periods of development, which ultimately result in a disease state. By understanding FOAD, health care professionals and policy makers will make this issue a high health care priority and implement preventive measures and treatment for those at higher risk for chronic diseases.

Serum dioxins and polychlorinated biphenyls are associated with growth among Russian boys

OBJECTIVE

We evaluated the associations of serum dioxins and polychlorinated biphenyls (PCBs) with longitudinally assessed growth measurements among peripubertal Russian boys.

METHODS

A total of 499 boys from Chapaevsk, Russia, aged 8 to 9 years were enrolled in the study from 2003 to 2005 and were followed prospectively for 3 years. Blood samples were collected and physical examinations were conducted at entry and repeated at annual study visits. Multivariate mixed-effects regression models for repeated measures were used to examine the associations of serum dioxins and PCBs with longitudinal measurements of BMI, height, and height velocity.

RESULTS

Serum dioxin (total 2005 toxic equivalency [TEQ] median: 21.1 pg/g lipid) and PCBs (median sum of PCBs: 250 ng/g lipid) were measured in 468 boys. At study entry and during 3 years of follow-up, >50% of the boys had age-adjusted BMI and height z scores within 1 SD of World Health Organization-standardized mean values for age. Boys in the highest exposure quintile of the sum of dioxin and PCB concentrations and total TEQs had a significant decrease in mean BMI z scores of 0.67 for dioxins and TEQs and 1.04 for PCBs, compared with boys in the lowest exposure quintile. Comparison of the highest versus the lowest quintile revealed that higher serum PCB concentrations were associated with significantly lower height z scores (mean z-score decrease: 0.41) and height velocity (mean decrease: 0.19 cm/year) after 3 years of follow-up.

CONCLUSIONS

Our findings suggest that exposures to dioxins and PCBs are associated with reduced growth during the peripubertal period and may compromise adult body mass, stature, and health.