The impact of reproductive and menstrual history on bone mineral density in Chinese women

Adolescent Sport Participation and Age at Menarche in Relation to Midlife Body Composition, Bone Mineral Density, Fitness, and Physical Activity

This study aimed to investigate the associations of competitive sport participation in adolescence and age at menarche (AAM) with body composition, femoral neck bone mineral density (BMD), physical performance, and physical activity (PA) in middle-aged women. 1098 women aged 47–55 years formed the sample of this retrospective study. Participants self-reported their PA level at age 13–16 years and AAM. The protocol also included dual-energy X-ray absorptiometry, physical performance tests, and accelerometer-measured PA. Participants were divided into three groups according to their PA level at the age of 13–16 (no exercise, regular PA, and competitive sport) and according to their AAM (≤12, 13, and ≥14 years). After adjusting for potential confounding factors, participation in competitive sport at age 13–16 was associated with higher midlife lean mass and BMD, and better physical performance compared to groups with no exercise or regular PA. Individuals with AAM ≥ 14 years had lower midlife BMI and fat mass than participants in the other AAM groups and pre- and perimenopausal women with AAM ≥ 14 years had lower BMD than those with AAM ≤ 12. The findings indicate that participation in competitive sport in adolescence is associated with healthier body composition, higher BMD, and better physical performance in midlife, but BMD might be impaired if menarche occurs late.

Association between breastfeeding and osteoporotic hip fracture in women: a dose-response meta-analysis

Objective

Approximately 300 mg of calcium a day is provided into infants to maintain the physical development of infants, and 5 to 10% bone loss occurs in women during breastfeeding. Hip fractures are considered the most serious type of osteoporotic fracture. We performed this meta-analysis to investigate the association between breastfeeding and osteoporotic hip fractures.

Material and methods

PubMed and Embase were searched until May 1, 2019, for studies evaluating the relationship between breastfeeding and osteoporotic hip fracture in women. The quality of the included studies was evaluated by the methodological index for non-randomized studies (MINORS). For the dose-response meta-analysis, we used the “generalized least squares for trend estimation” method proposed by Greenland and Longnecker to take into account the correlation with the log RR estimates across the duration of breastfeeding.

Results

Seven studies were moderate or high quality, enrolling a total of 103,898 subjects. The pooled outcomes suggested that breastfeeding can decrease the incidence of osteoporotic hip fracture (RR = 0.64 (95% CI 0.43, 0.95), P = 0.027). Dose-response analysis demonstrated that the incidence of osteoporotic hip fracture decreased with the increase of breastfeeding time. The RR and 95% CI for 3 months, 6 months, 12 months, and 24 months were RR = 0.93, 95% CI 0.88, 0.98; RR = 0.87, 95% CI 0.79, 0.96; RR = 0.79, 95% CI 0.67, 0.92; and RR = 0.76, 95% CI 0.59, 0.98, respectively, whereas no significant relationship was found between them when the duration of breastfeeding time was more than 25 months.

Conclusions

Our meta-analysis demonstrated that the incidence of osteoporotic hip fracture decreased with the extension of breastfeeding time. However, there is no significant relationship between them when the duration of breastfeeding time was more than 25 months.

Age at menarche and osteoporosis: A Mendelian randomization study

PURPOSE

Traditional epidemiological studies suggest that there is an association between age at menarche (years) (AAM) and bone mineral density (BMD) at the sites of the femoral neck and lumbar spine (FNK and LS BMD), indicating a potentially important relationship between AAM and the development of osteoporosis (OP). However, these findings may be influenced by unmeasured confounding factors that can obscure the true relationship between the phenotypic traits. Therefore, we performed Mendelian randomization (MR) analyses to determine whether there is a causal relationship between AAM and BMD (FNK and LS BMD), where late AAM may increase the risk of developing OP.

METHODS

Adopting a two-sample MR approach we incorporated genome-wide association (GWAS) summary statistics from the Reproductive Genetics (ReproGen) Consortium (n = 182,416) (females only) and the GEnetic Factors for OSteoporosis (GEFOS) Consortium (n = 53,236) (both males and females).

RESULTS

Using this MR approach we discovered that each additional year in AAM is associated with a modest reduction in FNK BMD (β = -0.072 se = 0.022, 95% CI (-0.115, -0.030), p = 0.001) and LS BMD ((β = -0.072, se = 0.025, 95% CI (-0.121, -0.023), p = 0.004), and therefore influences OP susceptibility.

CONCLUSIONS

This study demonstrates that AAM in females may play a causal role in OP etiology and provides novel insights into the pathophysiology of bone related diseases like osteoporosis, osteopenia and fracture.

SUMMARY

Our study demonstrates that AAM in females may play a causal role in OP etiology and provides novel insights into the pathophysiology of bone related diseases like osteoporosis, osteopenia and fracture. By adopting Mendelian Randomization approaches, our study was not susceptible to bias from unmeasured confounders or reverse causation.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

O efeito da amamentação na massa óssea de mulheres na pós-menopausa: revisão sistemática de estudos observacionais

Objetivos:avaliar o efeito da amamentação na massa óssea de mulheres na pós-menopausa.Métodos:trata-se de revisão sistemática de estudos observacionais. A pesquisa da literatura foi realizada nas bases de dados bibliográficos Lilacs, Medline e Scopus, em junho de 2015, sem restrição quanto ao ano de publicação. Para ser incluído nesta revisão, o artigo deveria avaliar o histórico de amamentação e a massa óssea na pós-menopausa, sendo suas referências checadas para busca de novos estudos. Dois revisores, de forma independente, realizaram a extração de dados e a avaliação da suscetibilidade a vieses dos estudos.Resultados:foram selecionados 34 estudos, dos quais seis (26,5%) mostraram que a prática de amamentação aumentou significativamente a massa óssea e 15 (44%) encontraram o inverso. Constatou-se grande diversidade entre os estudos quanto à população de estudo, mensuração da exposição e sítios de avaliação da massa óssea, dificultando a comparabilidade entre os resultados.Conclusões:a marcante heterogeneidade dos estudos torna inconclusiva a direção da associação entre a amamentação e a massa óssea em mulheres na pós-menopausa, sendo necessários estudos com maior rigor metodológico para avaliar esse problema de grande relevância para as áreas clínica e de saúde pública.

Incidence of and factors for self-reported fragility fractures among middle-aged and elderly women in rural Korea: an 11-year follow-up study

Objectives:

This community-based cohort study was performed to investigate the incidence of and factors related to self-reported fragility fractures among middle-aged and elderly women living in rural Korea.

Methods:

The osteoporosis cohort recruited 430 women 40 to 69 years old in 1999, and 396 of these women were followed over 11 years. In 1999, questionnaires from all participants assessed general characteristics, medical history, lifestyle, menstrual and reproductive characteristics, and bone mineral density. In 2010, self-reported fractures and the date, site, and cause of these fractures were recorded. Cox proportional hazards models were used to calculate hazard ratios (HRs).

Results:

Seventy-six participants among 3949.7 person-years experienced fragility fractures during the 11-year follow-up. The incidence of fragility fractures was 1924.2 per 100 000 person-years (95% confidence interval [CI], 1491.6 to 2356.8). In the multivariate model, low body mass index (HR, 2.66; 95% CI, 1.13 to 6.24), a parental history of osteoporosis (HR, 2.03; 95% CI, 1.18 to 3.49), and postmenopausal status (HR, 3.50; 95% CI, 1.05 to 11.67) were significantly related to fragility fracture.

Conclusions:

Fracture prevention programs are needed among postmenopausal, rural, Korean women with a low body mass index and parental history of osteoporosis Korea.

Association analyses of RANKL/RANK/OPG gene polymorphisms with femoral neck compression strength index variation in Caucasians

Femoral neck compression strength index (fCSI), a novel phenotypic parameter that integrates bone density, bone size, and body size, has significant potential to improve hip fracture risk assessment. The genetic factors underlying variations in fCSI, however, remain largely unknown. Given the important roles of the receptor activator of the nuclear factor-kappaB ligand/receptor activator of the nuclear factor-kappaB/osteoprotegerin (RANKL/RANK/OPG) pathway in the regulation of bone remodeling, we tested the associations between RANKL/RANK/OPG polymorphisms and variations in fCSI as well as its components (femoral neck bone mineral density [fBMD], femoral neck width [FNW], and weight). This was accomplished with a sample comprising 1873 subjects from 405 Caucasian nuclear families. Of the 37 total SNPs studied in these three genes, 3 SNPs, namely, rs12585014, rs7988338, and rs2148073, of RANKL were significantly associated with fCSI (P = 0.0007, 0.0007, and 0.0005, respectively) after conservative Bonferroni correction. Moreover, the three SNPs were approximately in complete linkage disequilibrium. Haplotype-based association tests corroborated the single-SNP results since haplotype 1 of block 1 of the RANKL gene achieved an even more significant association with fCSI (P = 0.0003) than any of the individual SNPs. However, we did not detect any significant associations of these genes with fBMD, FNW, or weight. In summary, our findings suggest that the RANKL gene may play an important role in variation in fCSI, independent of fBMD and non-fBMD components.

Effect of parity on phalangeal bone mineral density in post-menopausal Sri Lankan women: a community based cross-sectional study

There is paucity of studies related to parity and bone mineral density in South Asian countries. We recruited 713 healthy, community dwelling post-menopausal women from seven provinces in Sri Lanka for this survey. The number of pregnancies, including miscarriages beyond 20 weeks of gestation, was recorded. Women with diseases and those who have taken drugs that can affect bone mineral density (BMD) were excluded (n = 15). Phalangeal BMD and bone mineral content (BMC) were measured using AccuDEXA in 713 women. Mean (SE) BMD of nulliparous women (n = 32), women with one to two pregnancies (n = 284), three to four pregnancies (n = 290) and more than four pregnancies (n = 107) were 0.437(0.014), 0.454(0.005), 0.455(0.005) and 0.417(0.006) g/cm(2), respectively (P < 0.001). Corresponding mean (SE) BMCs were 1.30(0.063), 1.41(0.021), 1.43(0.022) and 1.32(0.033) g, respectively (P < 0.001). Women with more than four pregnancies were older and lighter when compared with other groups. When results were adjusted for current age and current weight, differences in mean BMD and BMC between groups became non-significant. BMD of nulliparous women remained low in all analyses. We report a significant difference in unadjusted phalangeal BMD in women categorized according to their parity. Women with one to four pregnancies had the highest phalangeal BMD and BMC, while multi-parous (more than four pregnancies) and nulliparous women had lower values. However, in an adjusted analysis, the differences in BMD and BMC were partially explained by the differences of age and body weight between the groups and the unique effect of parity was difficult to determine. Women with lower BMD may have a higher risk of future fractures.

Prevalence and determinants of osteoporosis among men aged 50 years or more in Sri Lanka: a community-based cross-sectional study

SUMMARY: This study, based on phalangeal bone mineral density (BMD) of 1,174 community dwelling male volunteers aged 50 years or more from seven provinces in Sri Lanka, shows 5.8% prevalence of osteoporosis among them. Advancing age, less physical activity, and low body weight were associated with low BMD. Men with larger families were more likely to have a lower bone mineral density. PURPOSE: The prevalence of osteoporosis among Sri Lankans is not well-known. We wished to estimate the prevalence and determinants of osteoporosis among older men in Sri Lanka. METHODS: One thousand one hundred seventy-four healthy, community dwelling male volunteers, aged 50 years or more from seven out of nine provinces in Sri Lanka underwent phalangeal bone mineral density estimation using an AccuDXA(R) scanner. We calculated T scores using the local reference data, and subjects with T score equal or less than -2.5 was considered to have osteoporosis. RESULTS: Sixty-six men (5.8%) were detected to have osteoporosis. In contrast to men in the highest tertile of bone mineral density, men in the lowest tertile were older (60.0 versus 55.8 years, p < 0.001), lighter (56.3 versus 65.6 kg, p < 0.001), less physically active (16.1% versus 5.5%, p < 0.001) and had larger families consisting of four or more children (36% versus 20.9%, p < 0.001). Smoking, alcohol, or milk consumption showed no association with bone mineral density. CONCLUSIONS: We report 5.8% prevalence of osteoporosis among men older than 50 years in Sri Lanka, and advancing age, less physical activity, and low body weight were associated with low bone mineral density. Men with larger families were more likely to have a lower bone mineral density.

Cross-calibration and minimum precision standards for dual-energy X-ray absorptiometry: the 2005 ISCD Official Positions

The International Society for Clinical Densitometry (ISCD) Committee on Standards of Bone Measurement (CSBM) consists of experts in technical aspects of bone densitometry. The CSBM recently reviewed the scientific literature on cross-calibration and precision assessment. A report with recommendations was presented at the 2005 ISCD Position Development Conference (PDC). Based on a thorough review of the data by the ISCD Expert Panel during the conference, the ISCD adopted Official Positions with respect to (1) cross-calibration when changing or replacing hardware; (2) the approach to cross-calibration when an entire system is changed to one made by either the same or a different manufacturer; (3) when no cross-calibration study or bone mineral density (BMD) comparison is done between facilities; and (4) the minimum acceptable precision for an individual technologist. We present here the ISCD Official Positions on these topics that were established as a result of the 2005 PDC, together with the associated rationales and supportive evidence.