Maternal smoking during pregnancy, growth, and bone mass in prepubertal children

Early-life tobacco smoke elevating later-life osteoporosis risk: Mediated by telomere length and interplayed with genetic predisposition

INTRODUCTION

The growing prevalence of osteoporosis (OP) in an aging global population presents a significant public health concern. Tobacco smoke negatively affects bone turnover, leading to reduced bone mass and heightened OP and fracture risk. However, the impact of early-life tobacco smoke exposure on later-life OP risk remains unclear.

OBJECTIVES

This study was to explore the effects of early-life tobacco smoke exposure on incident OP risk in later life. The mediating role of telomere length (TL) and the interaction with genetic predisposition were also studied.

METHODS

Data on in utero tobacco smoke exposure (IUTSE) status and age of tobacco use initiation from the UK Biobank were used to estimate early-life tobacco smoke exposure. Incident OP cases were identified according to health-related records. Linear, Cox, and Laplace regression models were mainly used for data analysis.

RESULTS

Individuals with IUTSE showed a higher OP risk [hazard ratio (HR): 1.06, 95 % confidence interval (CI): 1.01, 1.11] and experienced earlier OP onset by 0.30 years [50th percentile difference = -0.30, 95 % CI: -0.51, -0.09] compared to those without. Participants initiating tobacco smoke in childhood, adolescence, and adulthood had 1.41 times (95 % CI: 1.23, 1.61), 1.17 times (95 % CI:1.10, 1.24), and 1.14 times (95 % CI: 1.07, 1.20) the risk of OP, respectively, compared to never smokers. They also experienced earlier OP onset by 2.16, 0.95, and 0.71 years, sequentially. The TL significantly mediated the early-life tobacco exposure and OP association. Significant joint and interactive effects were detected between early-life tobacco smoke exposure and genetic elements.

CONCLUSIONS

Our findings implicate that early-life tobacco smoke exposure elevates the later-life OP risk, mediated by telomere length and interplayed with genetic predisposition. These findings highlight the importance of early-life intervention against tobacco smoke exposure and ageing status for precise OP prevention, especially in individuals with a high genetic risk.

Perturbations in Osteogenic Cell Fate Following Exposure to Constituents Present in Tobacco: A Combinatorial Study

Tobacco smoke contains between 7000 and 10,000 constituents, and only an evanescently low number of which have been identified, let alone been evaluated for their toxicity. Recently, the Food and Drug Administration has published a list of 93 chemical tobacco constituents that are harmful or potentially harmful to a number of cellular processes. However, their effect on developing skeletal cells is unknown. In this study, we used ToxPI, a computational tool, to prioritize constituents on this list for screening in osteogenically differentiating human embryonic stem cells and fibroblasts. In selected endpoint assays, we evaluated the potential of these chemicals to inhibit osteogenic differentiation success as well as their cytotoxicity. Six of these chemicals, which were ascribed an embryotoxic potential in our screen, as well as nicotine, which was not found to be osteotoxic in vitro, were then evaluated in combinatorial exposures, either in pairs of two or three. No one single chemical could be pinpointed as the culprit of reduced calcification in response to tobacco exposure. Combining chemicals at their half-maximal inhibitory concentration of differentiation often elicited expected decreases in calcification over the individual exposures; however, cytotoxicity was improved in many of the dual combinations. A reverse response was also noted, in which calcification output improved in combinatorial exposures. Results from ternary combinations reflected those from double combinations. Thus, the results from this study suggest that it may be difficult to isolate single chemicals as the primary drivers of skeletal embryotoxicity and that the full combination of chemicals in tobacco smoke may produce the hypomineralization phenotype that we have so far observed in vitro in human embryonic stem cells as well as in vivo in zebrafish.

Early Life Programming of Skeletal Health

PURPOSE OF REVIEW

Increasing bone mineral accrual during childhood might delay the onset of osteoporosis. We discuss the scientific evidence for early life approaches to optimising skeletal health.

RECENT FINDINGS

There is an ever-growing body of evidence from observational studies suggesting associations between early life exposures, particularly during foetal development, and bone mineral density (BMD). The findings of such studies are often heterogeneous, and for some exposures, for example, maternal smoking and alcohol intake in pregnancy or age at conception, intervention studies are not feasible. The most frequently studied exposures in intervention studies are calcium or vitamin D supplementation in pregnancy, which overall suggest positive effects on offspring childhood BMD. Maternal calcium and/or vitamin D supplementation during pregnancy appear to have positive effects on offspring BMD during early childhood, but further long-term follow-up is required to demonstrate persistence of the effect into later life.

Exposure to Cigarette Smoke Impedes Human Osteoblast Differentiation Independently of Nicotine

INTRODUCTION

Tobacco smoking has been implicated in an array of adverse health outcomes, including those that affect adult bone. However, little is known about the impact of tobacco products on developing bone tissue as it develops in the embryo.

AIMS AND METHODS

Here, human embryonic stem cells were differentiated into osteoblasts in vitro and concomitantly exposed to various concentrations of smoke solutions from two conventional, one additive-free and two harm-reduction brands of cigarettes. Differentiation inhibition was determined by calcium assays that quantified matrix mineralization and compared to the cytotoxicity of the tobacco product.

RESULTS

Exposure to mainstream smoke from conventional and additive-free cigarettes caused no inhibition of cell viability or mineralization, while sidestream smoke (SS) concentration-dependently produced cell death. In contrast, mineralization was inhibited only by the highest mainstream concentration of harm-reduction smoke solution. Additionally, sidestream smoke solution from the harm-reduction cigarettes impeded calcification at concentrations lower than those determined to be cytotoxic for conventional products.

CONCLUSIONS

Sidestream smoke impaired in vitro osteogenesis at subtoxic concentrations. In addition, though often perceived as safer, smoke from harm-reduction cigarettes was more potent in inhibiting in vitro osteogenesis than smoke from conventional cigarettes.

IMPLICATIONS

This study adds to a growing list of adverse outcomes associated with pre-natal tobacco exposure. Specifically, in vitro exposure to tobacco products interfered with osteogenic differentiation of human embryonic stem cells, a well-established surrogate model for human embryonic bone development. Contrasting a diverse array of tobacco products unveiled that sidestream smoke was generally more developmentally osteotoxic than mainstream smoke and that harm-reduction products may not be less harmful than conventional products, adverse effects that were seemingly independent of nicotine.

Developmental programming of macrophages by early life adversity

Macrophages are central elements of all organs, where they have a multitude of physiological and pathological functions. The first macrophages are produced during fetal development, and most adult organs retain populations of fetal-derived macrophages that self-maintain without major input of hematopoietic stem cell-derived monocytes. Their developmental origins make macrophages highly susceptible to environmental perturbations experienced in early life, in particular the fetal period. It is now well recognized that such adverse developmental conditions contribute to a wide range of diseases later in life. This chapter explores the notion that macrophages are key targets of environmental adversities during development, and mediators of their long-term impact on health and disease. We first briefly summarize our current understanding of macrophage ontogeny and their biology in tissues and consider potential mechanisms by which environmental stressors may mediate fetal programming. We then review evidence for programming of macrophages by adversities ranging from maternal immune activation and diet to environmental pollutants and toxins, which have disease relevance for different organ systems. Throughout this chapter, we contemplate appropriate experimental strategies to study macrophage programming. We conclude by discussing how our current knowledge of macrophage programming could be conceptualized, and finally highlight open questions in the field and approaches to address them.

Height and bone mineral content after inhaled corticosteroid use in the first 6 years of life

BACKGROUND

Infants and young children might be particularly susceptible to the potential side effects from inhaled corticosteroid (ICS) on height and bone mineral content (BMC), but this has rarely been studied in long-term prospective studies.

METHODS

Children from two Copenhagen Prospective Studies on Asthma in Childhood cohorts were included. ICS use was registered prospectively from birth to age 6 and the cumulative dose was calculated. Primary outcomes were height and BMC from dual-energy X-ray absorptiometry (DXA) scans at age 6.

RESULTS

At age 6, a total of 930 children (84%) from the cohorts had a valid height measurement and 792 (71%) had a DXA scan. 291 children (31%) received a cumulated ICS dose equivalent to or above 10 weeks of standard treatment before age 6. We found an inverse association between ICS use and height, -0.26 cm (95% CI: -0.45 to -0.07) per 1 year standard treatment from 0 to 6 years of age, p=0.006. This effect was mainly driven by children with ongoing treatment between age 5 and 6 years (-0.31 cm (95% CI: -0.52 to -0.1), p=0.004), while there was no significant association in children who stopped treatment at least 1 year before age 6 (-0.09 cm (95% CI: -0.46 to 0.28), p=0.64). There was no association between ICS use and BMC at age 6.

CONCLUSIONS

ICS use in early childhood was associated with reduced height at age 6 years but only in children with continued treatment in the sixth year of life.

Extracellular Vesicles in Premature Aging and Diseases in Adulthood Due to Developmental Exposures

The developmental origins of health and disease (DOHaD) is a paradigm that links prenatal and early life exposures that occur during crucial periods of development to health outcome and risk of disease later in life. Maternal exposures to stress, some psychoactive drugs and alcohol, and environmental chemicals, among others, may result in functional changes in developing fetal tissues, creating a predisposition for disease in the individual as they age. Extracellular vesicles (EVs) may be mediators of both the immediate effects of exposure during development and early childhood as well as the long-term consequences of exposure that lead to increased risk and disease severity later in life. Given the prevalence of diseases with developmental origins, such as cardiovascular disease, neurodegenerative disorders, osteoporosis, metabolic dysfunction, and cancer, it is important to identify persistent mediators of disease risk. In this review, we take this approach, viewing diseases typically associated with aging in light of early life exposures and discuss the potential role of EVs as mediators of lasting consequences.

An Evaluation of Human Induced Pluripotent Stem Cells to Test for Cardiac Developmental Toxicity

To prevent congenital defects arising from maternal exposure, safety regulations require pre-market developmental toxicity screens for industrial chemicals and pharmaceuticals. Traditional embryotoxicity approaches depend heavily on the use of low-throughput animal models which may not adequately predict human risk. The validated embryonic stem cell test (EST) developed in murine embryonic stem cells addressed the former problem over 15 years ago. Here, we present a proof-of-concept study to address the latter challenge by updating all three endpoints of the classic mouse EST with endpoints derived from human induced pluripotent stem cells (hiPSCs) and human fibroblasts. Exposure of hiPSCs to selected test chemicals inhibited differentiation at lower concentrations than observed in the mouse EST. The hiPSC-EST also discerned adverse developmental outcomes driven by novel environmental toxicants. Evaluation of the early cardiac gene TBX5 yielded similar toxicity patterns as the full-length hiPSC-EST. Together, these findings support the further development of hiPSCs and early molecular endpoints as a biologically relevant embryotoxicity screening approach for individual chemicals and mixtures.

Associations between Inhaled Corticosteroid in the First 6 Years of Life and Obesity Related Traits

Rationale Infants and young children might be particularly susceptible to the potential clinical side effects of inhaled corticosteroids (ICS) on body mass index (BMI), adiposity rebound and body composition, but this has rarely been studied in long-term studies in this age-group. Objective To determine the association between ICS exposure in the first 6 years of life on BMI, adiposity rebound, body composition and blood lipid levels. Methods Children from the two Copenhagen Prospective Studies on Asthma in Childhood mother-child cohorts were included. ICS use was registered prospectively to age 6 and the cumulative dose was calculated. Multiple linear regression models were used for analysis. Measurements and Main Results A total of 932 (84%) of the 1111 children from the COPSAC cohorts had data on BMI, 786 (71%) had DXA scan data at age 6 years, and 815 (73%) had adiposity rebound age calculated. 291 children (31%) received a cumulative ICS dose > 10 weeks of standard treatment before age 6. ICS treatment during 0-6 years of age was associated with an increased BMI z-score; 0.05 SD [95% CI: 0.005 to 0.09] per one-year standard treatment, p=0.03, an earlier age at adiposity rebound; -0.18 year [95% CI: -0.28 to -0.08], p=0.0006, and a 2 % increased geometric mean android fat percentage, p=0.05. ICS exposure and DXA scan data were not associated. Conclusions ICS use in early childhood was associated with increased BMI z-score at age six, an earlier adiposity rebound and a trend of association with increased android body fat percentage.

Association between maternal smoking during pregnancy and risk of bone fractures in offspring: a systematic review and meta-analysis

This study aimed to investigate the effect of maternal smoking during pregnancy (MSDP) on the risk of bone fractures in the offspring through a systematic review and meta-analysis. The PubMed, Web of Science, and Scopus databases were systematically searched for relevant articles published through July 2019. According to heterogeneity, the pooled risk ratio (RR) and odds ratio (OR) and their corresponding 95% confidence interval (CI) were obtained using fixed or random effects models. The heterogeneity and quality of the included studies were assessed by the I-squared (I2 ) statistic and the Newcastle-Ottawa scale, respectively. Sensitivity analyses were performed to test the effect of MSDP misclassification on the results. The review of 842 search records yielded 5 studies including 8,746 mother-child pairs that were included in the meta-analysis. Pooling adjusted effect measures showed that MSDP was not associated with a later risk of bone fractures in the offspring (pooled RR, 1.15; 95% CI, 0.84-1.58; I2 =66.8%; P=0.049). After the adjustment for misclassification, MSDP may be associated with a 27% increased risk of bone fracture (pooled OR, 1.27; 95% CI, 1.00-1.62; I2 =0%; P=0.537). After the adjustment for misclassification, MSDP is associated with an increased risk of bone fractures among children whose mothers smoked during pregnancy.

Firstborn sex defines early childhood growth of subsequent siblings

Animal studies have shown that maternal resource allocation can be sex-biased in order to maximize reproductive success, yet this basic concept has not been investigated in humans. In this study, we explored relationships between maternal factors, offspring sex and prenatal and postnatal weight gain. Sex-specific regression models not only indicated that maternal ethnicity impacted male (n = 2456) and female (n = 1871) childrens postnatal weight gain differently but also that parity and mode of feeding influenced weight velocity of female (β ± s.e. = -0.31 ± 0.11 kg, p = 0.005; β ± s.e. = -0.37 ± 0.11 kg, p < 0.001) but not male offspring. Collectively, our findings imply that maternal resource allocation to consecutive offspring increases after a male firstborn. The absence of this finding in formula fed children suggests that this observation could be mediated by breast milk. Our results warrant further mechanistic and epidemiological studies to elucidate the role of breastfeeding on the programming of infant growth as well as of metabolic and cardiovascular diseases, with potential implications for tailoring infant formulae according to sex and birth order.

Nutrients, Diet, and Other Factors in Prenatal Life and Bone Health in Young Adults: A Systematic Review of Longitudinal Studies

Optimizing skeletal health in early life has potential effects on bone health later in childhood and in adulthood. We aimed to evaluate the existing evidence that maternal exposures during pregnancy have an impact on the subsequent bone health among offspring in young adults aged between 16 and 30 years. The protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO) (ID: CRD42019126890). The search was conducted up to 2 April 2019. We included seven observational prospective cohort studies that examined the association between maternal dietary factors, vitamin D concentration, age, preeclampsia, and smoking with any bone indices among offspring. The results indicated that high concentrations of maternal vitamin D; low fat intake; and high intakes of calcium, phosphorus, and magnesium may increase the bone mineral density in offspring at age 16. Evidence also suggests that the offspring of younger mothers may have a higher peak bone mass. It remains inconclusive whether there is an influence of preeclampsia or maternal smoking on bone health among young adults. Our assessment of internal validity warrants a cautious interpretation of these results, as all of the included studies were judged to have serious risks of bias. High-quality studies assessing whether prenatal prognostic factors are associated with bone health in young adults are needed.

Associations of Breastfeeding, Maternal Smoking, and Birth Weight With Bone Density and Microarchitecture in Young Adulthood: a 25-Year Birth-Cohort Study

We have found that early-life exposures are associated with areal bone mineral density (aBMD) at ages 8 and 16 years. This study aimed to assess whether these associations persist into young adulthood when peak bone mass (PBM) is achieved and extend this analysis to microarchitecture. Participants were followed from perinatal period to 25 years old (n = 201). Outcomes were total body, spine, and hip aBMD (by dual-energy X-ray absorptiometry [DXA]), and cortical and trabecular bone measures at the distal radius and tibia (by high-resolution peripheral quantitative computed tomography [HRpQCT]). Early-life exposures including breastfeeding, maternal smoking during pregnancy, and birth weight. Sex, weight, height, vegetables, fruit and calcium intake at age 25 years were regarded as potential confounders in the analysis. There were significant interactions between period of gestation and early-life exposures for bone measures, so all analyses were stratified by period of gestation. Breastfeeding was beneficially associated with hip and total body aBMD, total, cortical and trabecular volumetric BMD (vBMD), cortical thickness, porosity, trabecular number (Tb.N), separation (Tb.Sp), and bone volume fraction (Tb.BV/TV) at radius and/or tibia at age 25 years in participants born prematurely (β ranged from -0.92 to 0.94), but there were no associations in those born at term. Maternal smoking had no association with any DXA/HRpQCT measures in those born prematurely but was detrimentally associated with inner transitional zone porosity and Tb.N (β = 0.40 and β = -0.37, respectively) in those full-term participants. Associations of birth weight with bone measures did not persist after adjustment for weight gain since birth. Breastfeeding was associated with a lower risk of lower limb fractures and maternal smoking had a deleterious association with upper limb fractures. In conclusion, breastfeeding and maternal smoking may have effects on peak bone microarchitecture whereas the association with birth weight is countered by subsequent growth. © 2020 American Society for Bone and Mineral Research.

Maternal alcohol consumption during pregnancy associates with bone fractures in early childhood. A birth-cohort study of 6718 participants

Fractures are common injuries in children, but their underlying biological and environmental risk factors are not well known. Maternal alcohol consumption during pregnancy is a known risk factor for bone malformations and impaired growth, in connection with Fetal Alcohol Spectrum Disorders (FASD). There is evidence that even lower doses of alcohol than what is needed for FASD can cause changes in the developing bone. Birth weight and length may also associate to childhood fractures. The aim of this study was to find out whether there exist associations between maternal alcohol use during pregnancy, birth weight or length and fractures of the long bones in childhood. A prospective birth cohort was performed, including all women in Northern Finland with an expected date of delivery between July 1985 and June 1986, and their offspring (N = 9432). The National Hospital Discharge Register (NHDR) provided the information on inpatient treated fractures. The subjects who declined participation or were treated as outpatient were excluded. The final study population consisted of 6718 children (71.2%). 98 (1.5%) of them suffered from inpatient treated fracture of a long bone (N = 105). Maternal alcohol consumption during pregnancy was inquired by questionnaires during late pregnancy or shortly after parturition. The birth length and weight were recorded immediately after birth. Binomial regression analysis was used to determine the association between the potential explanatory variables and bone fractures. Gender, socioeconomic status of the family, maternal age, premature birth, body mass index (BMI) of the children and maternal smoking during pregnancy were taken as possible confounders. In this study, the maternal alcohol consumption during pregnancy was associated to 2.22-fold (CI 1.09-4.12, p < 0.02) increased risk of a long bone fracture before the age of eight. Birth weight or length did not associate to childhood fractures. Bone fractures are an important cause of morbidity in childhood. Their prevention should start from the prenatal period by protecting the fetus from the alcohol exposure.

Association between maternal smoking and child bone mineral density: a systematic review and meta-analysis

Maternal smoking during pregnancy has detrimental effects on fetal development. The current review examined the differences in offspring's bone mineral density (BMD) between mothers smoked during pregnancy and those who did not. A systematic review and meta-analysis on the studies investigating the influence of maternal smoking during pregnancy on children or neonates' bone measures published up to October 30, 2018, was performed. BMD results measured at different body sites were pooled and then fixed or random effect models were used based on the presence of heterogeneity. The desired pooled effect size was the offspring's BMD mean difference with 95% confidence interval between smoker and non-smoker mothers. Sensitivity analysis was performed for birth weight and current weight, two important mediator/confounders causing heterogeneity. Overall, eight studies consisting of 17,931 participants aged from infancy to 18 years were included. According to the fixed effect model, the mean of BMD in offspring whose mothers smoked during pregnancy was 0.01 g/cm² lower than those with non-smoker mothers (95% CI = - 0.02 to - 0.002). However, subgroup meta-analysis adjusted for birth weight and current weight demonstrated no significant mean difference between BMD of children with smoker and non-smoker mothers (d = 0.06, 95% CI = -0.04 to 0.16, p value = 0.25 and d = - 0.005, 95% CI = - 0.01 to 0.004, p value = 0.28, respectively). According to available studies, it is suggested that maternal smoking during pregnancy does not have direct effect on the offspring's BMD. Instead, this association might be confounded by other factors such as placental weight, birth weight, and current body size of children.

Association of solid fuel use with risk of stunting in children living in China

Stunting adversely affects physical and mental outcomes of children. It has not been examined whether household air pollution from solid fuel combustion is a risk factor for stunting in children. In a total of 41,439 children aged 6-17 across China, height was measured using a unified protocol. Multivariable linear regression models and logistic regression models were used to assess the associations of solid fuel use for cooking/heating with stunting in children. Adjusted for covariates, cooking/heating with solid fuel was significantly associated with a lower z-score for height for age and sex (β = -0.21 [-0.32 to -0.09] and -0.17 [-0.31 to -0.03], respectively) and an increased risk of stunting with an estimated ORs of 1.34 [1.07~1.68] and 1.37 [1.02~1.83], respectively. The risk of stunting associated with solid fuel use was statistically significant in high-age children. And the effect was greater on girls than on boys, though the difference was not statistically significant. Our study suggested that Chinese children living in households using solid fuel had a significantly higher risk of stunting than those living in households using cleaner fuel.

Maternal smoking during pregnancy and fractures in offspring: national register based sibling comparison study

OBJECTIVE

To study the impact of maternal smoking during pregnancy on fractures in offspring during different developmental stages of life.

DESIGN

National register based birth cohort study with a sibling comparison design.

SETTING

Sweden.

PARTICIPANTS

1 680 307 people born in Sweden between 1983 and 2000 to women who smoked (n=377 367, 22.5%) and did not smoke (n=1 302 940) in early pregnancy. Follow-up was until 31 December 2014.

MAIN OUTCOME MEASURE

Fractures by attained age up to 32 years.

RESULTS

During a median follow-up of 21.1 years, 377 970 fractures were observed (the overall incidence rate for fracture standardised by calendar year of birth was 11.8 per 1000 person years). The association between maternal smoking during pregnancy and risk of fracture in offspring differed by attained age. Maternal smoking was associated with a higher rate of fractures in offspring before 1 year of age in the entire cohort (birth year standardised fracture rates in those exposed and unexposed to maternal smoking were 1.59 and 1.28 per 1000 person years, respectively). After adjustment for potential confounders the hazard ratio for maternal smoking compared with no smoking was 1.27 (95% confidence interval 1.12 to 1.45). This association followed a dose dependent pattern (compared with no smoking, hazard ratios for 1-9 cigarettes/day and ≥10 cigarettes/day were 1.20 (95% confidence interval 1.03 to 1.39) and 1.41 (1.18 to 1.69), respectively) and persisted in within-sibship comparisons although with wider confidence intervals (compared with no smoking, 1.58 (1.01 to 2.46)). Maternal smoking during pregnancy was also associated with an increased fracture incidence in offspring from age 5 to 32 years in whole cohort analyses, but these associations did not follow a dose dependent gradient. In within-sibship analyses, which controls for confounding by measured and unmeasured shared familial factors, corresponding point estimates were all close to null. Maternal smoking was not associated with risk of fracture in offspring between the ages of 1 and 5 years in any of the models.

CONCLUSION

Prenatal exposure to maternal smoking is associated with an increased rate of fracture during the first year of life but does not seem to have a long lasting biological influence on fractures later in childhood and up to early adulthood.

Maternal and child factors associated with bone length traits in children at 3 years of age

BACKGROUND

Exposure to sub-optimal maternal vitamin D status during pregnancy has been linked to inadequate in utero bone growth with potential for post-natal deficits, but reported findings are inconsistent. Possible reasons include measurement error in assessing bone length/height, or lack of adjustment for confounding variables such as maternal/infant diet, physical activity and season of birth. The objective of this study was to determine the maternal and child factors associated with bone length traits in children at 3 years of age as part of a longitudinal follow-up of a pregnancy cohort.

METHODS

Mother-child dyads enrolled in the Family Atherosclerosis Monitoring In early Life study were included. Maternal serum 25-hydroxyvitamin D (25(OH)D) concentration was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Anthropometry, physical activity by questionnaire and dietary assessment by food frequency questionnaire were completed for mothers during pregnancy (27-40 weeks gestation) and for children at 3 years with diet by 3-day food records (Nutritionist Pro). Whole body bone mineral density in mother and child (n = 473) was measured by dual-energy absorptiometry (DXA) at the 3 year visit. A software program was developed using MATLAB to derive bone length measurements from whole body DXA images using 8 long bones of each child. Association between maternal and child variables with offspring bone length was assessed using unadjusted and adjusted multivariate linear regression analyses.

RESULTS

In the final adjusted multivariate regression model, factors associated with child bone length were maternal height (p = 0.05), child birth length (p = 0.005) and child weight z-score at 3 years (p < 0.001). No association was observed between maternal serum 25(OH)D concentrations in pregnancy (of which 77% were in normal range) and child bone length.

CONCLUSION

In healthy Canadian mothers and their children, the factors associated with child bone length achieved at 3 years of age appear to be related to genetic traits rather than environmental exposures. Measures of the length of long bones in children using DXA scans may have provided a more accurate assessment of bone length than whole body height measures.

Prenatal influences on bone health in children

INTRODUCTION

Optimising bone health might reduce the burden of both fractures in childhood and fragility fractures in later life. A number of maternal dietary and non-dietary factors have been identified that might influence offspring bone health and represent targets for intervention.

AREAS COVERED

This article will outline the accrual of bone mineral throughout the life course and how observational and intervention studies have shown that maternal diet, in particular maternal calcium and 25-hydroxyvitamin D [25(OH)D] status, and lifestyle are associated with offspring bone mineralization. Studies examining the effects of maternal micronutrient supplementation on offspring bone mineral density (BMD) will also be discussed.

EXPERT COMMENTARY

There is a wealth of observational evidence relating maternal diet to offspring BMD. However, high quality randomized controlled trials, such as the ongoing MAVIDOS study, are needed before these findings can be definitively translated into public health advice.

Video-based kinetic analysis of calcification in live osteogenic human embryonic stem cell cultures reveals the developmentally toxic effect of Snus tobacco extract

Epidemiological studies suggest tobacco consumption as a probable environmental factor for a variety of congenital anomalies, including low bone mass and increased fracture risk. Despite intensive public health initiatives to publicize the detrimental effects of tobacco use during pregnancy, approximately 10-20% of women in the United States still consume tobacco during pregnancy, some opting for so-called harm-reduction tobacco. These include Snus, a type of orally-consumed yet spit-free chewing tobacco, which is purported to expose users to fewer harmful chemicals. Concerns remain from a developmental health perspective since Snus has not reduced overall health risk to consumers and virtually nothing is known about whether skeletal problems from intrauterine exposure arise in the embryo. Utilizing a newly developed video-based calcification assay we determined that extracts from Snus tobacco hindered calcification of osteoblasts derived from pluripotent stem cells early on in their differentiation. Nicotine, a major component of tobacco products, had no measurable effect in the tested concentration range. However, through the extraction of video data, we determined that the tobacco-specific nitrosamine N'-nitrosonornicotine caused a reduction in calcification with similar kinetics as the complete Snus extract. From measurements of actual nitrosamine concentrations in Snus tobacco extract we furthermore conclude that N'-nitrosonornicotine has the potential to be a major trigger of developmental osteotoxicity caused by Snus tobacco.

Effects of prenatal exposure to cigarettes on anthropometrics, energy intake, energy expenditure, and screen time in children

BACKGROUND

Maternal prenatal smoking is associated with downstream childhood obesity. Although animal research suggests reduced resting energy expenditure (REE), decreased physical activity (PA), and increased energy intake as mechanisms, these relationships are unclear in humans. The objectives were to examine the association of prenatal maternal smoking with non-volitional energy expenditure (REE and the thermic effect of feeding [TEF]), child adiposity, energy intake, free-living PA (daily light PA (LPA), daily moderate-to-vigorous PA (MVPA), daily sedentary behavior (SB)), and screen time (television and computer/video game) in children.

METHODS

As part of a longitudinal study, 46 children (n = 27 controls and n = 19 smoking exposed) with mean age 7.6 ± 2 years were recruited. Body weight and composition (Bioelectrical Impedance), height (Stadiometer), waist circumference (cm; tape), BMI (kg/m²), REE (kcal/day; indirect calorimetry), PA (minutes; Accelerometry), screen time (hours; self-report) and ad libitum energy intake (lunch buffet; 7-day food log) were measured. Effects sizes were evaluated using Cohen's d.

RESULTS

Relative to controls, after controlling for age and family income, children who were exposed to cigarette smoke in utero exhibited greater waist circumference (p = 0.04, Cohen's d = 1.03), percent body fat (%BF; p = 0.02, Cohen's d = 0.97), and a trend for BMI (p = 0.05, Cohen's d = 0.86). Exposed children did not differ in REE (trend for lower: p = 0.1, Cohen's d = 0.42) or TEF but were shown to have significantly higher ad libitum energy intake (p = 0.02, Cohen's D = 0.70) from the palatable lunch buffet, but not from the out of laboratory 7-day energy intake (p = 0.8). Examining screen time behaviors, exposed children spent more time watching television during the week (p = 0.03, Cohen's D = 0.82), and overall television watching (p = 0.02, Cohen's D = 0.80); there were no group differences in any other screen time behaviors.

CONCLUSIONS

Children exposed to cigarette smoke in utero exhibit greater adiposity, and this exposure may have as contributing factors higher screen time, ad libitum energy intake, and a trend for reduced REE. The data suggest that lifestyle factors such as diet and screen time represent targets for obesity prevention in a high-risk population of young children exposed to prenatal cigarette smoke. Findings also highlight the need for smoking cessation programs to reduce downstream obesity in offspring.

Familial resemblance in trabecular and cortical volumetric bone mineral density and bone microarchitecture as measured by HRpQCT

To estimate the heritability of bone geometry, volumetric bone mineral density (vBMD) and microarchitecture of trabecular (Tb) and cortical (Ct) bone measured by high resolution peripheral quantitative computerised tomography (HRpQCT) at the distal radius and tibia and to investigate the genetic correlations of these measures. Participants were 177 mother-offspring pairs from 162 families (mothers, mean age (SD) = 52.1 (4.7) years; offspring, 25.6 (0.73) years). Trabecular and cortical bone measures were obtained by HRpQCT. Multivariable linear regression was used to analyse the association of bone measures between mother and offspring. Sequential Oligogenic Linkage Analysis Routines (SOLAR) software was utilised to conduct quantitative genetic analyses. All maternal bone measures were independently associated with the corresponding bone measures in the offspring before and after adjustment for age, sex, weight and height. Heritability estimates ranged from 24% to 67% at the radius and from 42% to 74% at the tibia. The relationship for most bone geometry measures was significantly stronger in mother-son pairs (n = 107) compared with mother-daughter pairs (n = 70) (p < 0.05). In contrast, the heritability for most vBMD and microarchitecture measures were higher in mother-daughter pairs. Bivariate analyses found moderate to strong genetic correlations across all measures between radius and tibia (R_g = 0.49 to 0.93). Genetic factors have an important role in the development of bone geometry, vBMD and microarchitecture. These factors are strongly shared for the radius and tibia but vary by sex implying a role for imprinting.

Maternal smoking during pregnancy and offspring overweight: is there a dose-response relationship? An individual patient data meta-analysis

BACKGROUND/OBJECTIVES

A number of meta-analyses suggest an association between any maternal smoking in pregnancy and offspring overweight obesity. Whether there is a dose-response relationship across number of cigarettes and whether this differs by sex remains unclear.

SUBJECT/METHODS

Studies reporting number of cigarettes smoked during pregnancy and offspring BMI published up to May 2015 were searched. An individual patient data meta-analysis of association between the number of cigarettes smoked during pregnancy and offspring overweight (defined according to the International Obesity Task Force reference) was computed using a generalized additive mixed model with non-linear effects and adjustment for confounders (maternal weight status, breastfeeding, and maternal education) and stratification for sex.

RESULTS

Of 26 identified studies, 16 authors provided data on a total of 238,340 mother-child-pairs. A linear positive association was observed between the number of cigarettes smoked and offspring overweight for up to 15 cigarettes per day with an OR increase per cigarette of 1.03, 95% CI = [1.02-1.03]. The OR flattened with higher cigarette use. Associations were similar in males and females. Sensitivity analyses supported these results.

CONCLUSIONS

A linear dose-response relationship of maternal smoking was observed in the range of 1-15 cigarettes per day equally in boys and girls with no further risk increase for doses above 15 cigarettes.

Maternal smoking during pregnancy is associated with childhood bone fractures in offspring - A birth-cohort study of 6718 children

In children there is limited understanding about the biological and environmental risk factors of fractures. Therefore, we aimed to study the effect of maternal smoking on preschool children's fractures hypothesizing that the fracture risk might be programmed during intrauterine growth in means of disturbed bone formation. A prospective birth cohort included women living in Northern Finland with an expected date of delivery between July 1st, 1985 and June 30th, 1986 (N=9362), and their offspring (N=9432). Smoking was inquired during pregnancy and when the offspring reached seven years of age. Information on in-hospital-treated fractures among the children was collected from the National Hospital Discharge Register (NHDR). The cases who declined to participate or suffered from any bone dysplasia such as osteogenesis imperfecta or any malignancy were excluded, thus 6718 subjects (71.2%) were finally included. Poisson regression analysis with adjustment for gender, asthma, rheumatoid arthritis, socioeconomic status of the family, maternal age and body mass index (BMI) of the children was used to determine the association between maternal smoking during pregnancy and bone fractures. Maternal smoking during pregnancy was associated with a 1.83-fold (95% CI 1.06-3.02, p=0.022) increased risk of in-hospital-treated fractures at pre-school age. The fracture risk in childhood is perhaps increased as a result of modified bone development of the fetus due to maternal smoking.

Biochemical Markers of Bone Turnover and Fracture Prediction

Low bone mineral density is a strong risk factor for fractures in the older woman. Biochemical markers of bone turnover may predict fracture risk independently of bone mineral density. High levels of bone resorption markers are associated with increased risk of fracture in both retrospective and prospective studies, although the evidence for bone formation markers and fracture risk is equivocal. For example, the risk of fracture is increased up to two-fold in women with elevated levels of several markers of bone resorption. Prediction models have been developed to predict the 10–year risk of fracture using bone mineral density and biochemical markers of bone turnover and these could prove very useful in clinical practice.

Parental smoking during pregnancy shortens offspring's legs

One of the most severe detrimental environmental factors acting during pregnancy is foetal smoke exposure. The aim of this study was to assess the effect of maternal, paternal and parental smoking during pregnancy on relative leg length in 7- to 10-year-old children. The research conducted in the years 2001-2002 included 978 term-born children, 348 boys and 630 girls, at the age of 7-10 years. Information concerning the birth weight of a child was obtained from the health records of the women. Information about the mother's and the father's smoking habits during pregnancy and about the mothers' education level was obtained from a questionnaire. The influence of parental smoking on relative leg length, controlled for age, sex, birth weight and the mother's education, as a proxy measure of socioeconomic status, and controlled for an interaction between sex and birth weight, was assessed by an analysis of covariance, where relative leg length was the dependent variable, smoking and sex were the independent variables, and birth weight as well as the mother's education were the covariates. Three separate analyses were run for the three models of smoking habits during pregnancy: the mother's smoking, the father's smoking and both parents' smoking. Only both parents' smoking showed a significant effect on relative leg length of offspring. It is probable that foetal hypoxia caused by carbon monoxide contained in smoke decelerated the growth of the long bones of foetuses.

Does fetal smoke exposure affect childhood bone mass? The Generation R Study

We assessed the intrauterine influence of maternal smoking on childhood bone mass by comparing parental prenatal and postnatal smoking habits. We observed higher bone mass in children exposed to maternal smoking, explained by higher body weight. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth.

INTRODUCTION

Maternal smoking during pregnancy may adversely affect bone health in later life. By comparing the associations of maternal and paternal smoking and of prenatal and postnatal exposure with childhood bone measures, we aimed to explore whether the suggested association could be explained by fetal programming or reflects confounding by familial factors.

METHODS

In 5565 mothers, fathers and children participating in a population-based prospective cohort study, parental smoking habits during pregnancy and current household smoking habits were assessed by postal questionnaires. Total body bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry (DXA) at the median age of 6.0 years (IQR 0.37).

RESULTS

In confounder-adjusted models, maternal smoking during pregnancy was associated with a higher BMC of 11.6 g (95 % confidence interval (CI) 5.6, 17.5), a larger BA of 9.7 cm(2) (95 % CI 3.0, 16.4), a higher BMD of 6.7 g/cm(2) (95 % CI 2.4, 11.0) and a higher BMC of 5.4 g (95 % CI 1.3, 9.6) adjusted for BA of the child. Current weight turned out to mediate these associations. Among mothers who did not smoke, paternal smoking did not show evident associations with childhood bone measures. Also, household smoking practices during childhood were not associated with childhood bone measures.

CONCLUSIONS

Our results do not support the hypothesis of fetal smoke exposure affecting childhood bone mass via intrauterine mechanisms. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth.

Lifecourse relationship between maternal smoking during pregnancy, birth weight, contemporaneous anthropometric measurements and bone mass at 18years old. The 1993 Pelotas Birth Cohort

BACKGROUND

Maternal smoking during pregnancy is associated with short-term and also long-term harmful effects on offspring.

OBJECTIVE

The aim of this study is to evaluate the associations of maternal smoking during pregnancy with offspring bone health at 18years old, and the role of birth weight and contemporaneous height, weight and body mass index (BMI) in this association. Data from the 1993 Pelotas Birth Cohort were analyzed using path analysis stratified by sex. Adolescents at 18 years old (N=1512 males, 1563 females). DXA-determined total body bone mineral density (BMD) and bone mineral content (BMC) were assessed at 18 years old.

RESULTS

Each additional cigarette smoked during pregnancy was associated with a lower BMC by -4.20 g in males (95% CI -8.37; -0.05), but not in females [-2.22 g (95% CI -5.49; 1.04)]; weaker inverse associations were observed for BMD. This inverse association was explained by the influence of maternal smoking on birth weight and contemporaneous anthropometry, particularly height. A 1 kg higher birth weight was associated with a higher BMC by around 144 g in males and by around 186 g in females, and also with a higher BMD by around 0.019 g/cm(2) in males and by around 0.018 g/cm(2) in females, respectively.

CONCLUSIONS

Lifecourse analysis using path models has enabled to evaluate the role of mediators in the associations of maternal smoking during pregnancy and birth weight with bone mass in the offspring, thus generating improved understanding of the etiology of bone health and the importance of early life experiences.

Maternal predictors of neonatal bone size and geometry: the Southampton Women's Survey

Early growth is associated with later risk of osteoporosis and fractures. In this study, we aimed to evaluate the relationships between maternal lifestyle and body composition and neonatal bone size, geometry and density in the offspring. Participants were recruited from the Southampton Women's Survey, a unique prospective cohort of 12,500 initially non-pregnant women aged 20-34 years, resident in Southampton, UK. These women were studied in detail before and during pregnancy, and the offspring underwent anthropometric and bone mineral assessment (using dual energy-X-ray absorptiometry) at birth. A total of 841 mother-baby pairs were studied (443 boys and 398 girls). The independent predictors of greater neonatal whole body bone area (BA) and bone mineral content included greater maternal birthweight, height, parity, triceps skinfold thickness and lower walking speed in late pregnancy. Maternal smoking was independently associated with lower neonatal bone mass. Neonatal BA adjusted for birth length (a measure of bone width) was predicted positively by maternal parity and late pregnancy triceps skinfold thickness and negatively by late pregnancy walking speed. These findings were similar in both genders. We have confirmed, in a large cohort, previous findings that maternal lifestyle and body build predict neonatal bone mineral; additionally, maternal parity and fat stores and walking speed in late pregnancy were associated with neonatal bone geometry. These findings may suggest novel public health strategies to reduce the burden of osteoporotic fracture in future generations.

Early development and osteoporosis and bone health

Osteoporosis is a skeletal disorder characterized by low bone mass and micro-architectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. Evidence is now accumulating from human studies that programming of bone growth might be an important contributor to the later risk of osteoporotic fracture. Body weight in infancy is a determinant of adult bone mineral content, as well as of the basal levels of activity of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) and hypothalamo-pituitary-adrenal (HPA) axes, and recent work has suggested a central role for vitamin D. Epidemiological studies have shown that maternal smoking and nutrition during pregnancy influence intrauterine skeletal mineralization. Childhood growth rates have been directly linked to the risk of hip fracture many decades later, and now evidence is emerging from experimental animal studies that support these observational data. Recent studies have also highlighted epigenetic phenomena as potential mechanisms underlying the findings from epidemiological studies.

The association between breastfeeding, maternal smoking in utero, and birth weight with bone mass and fractures in adolescents: a 16-year longitudinal study

The aim of this birth cohort study was to determine whether early life factors (birth weight, breastfeeding, and maternal smoking) were associated with bone mass and fractures in 16-year-old adolescents. The results suggest that breastfeeding is associated with higher bone mass and lower fracture risk at age 16 but not in utero smoking or birth weight.

INTRODUCTION

There are limited data on early life influences on bone mass in adolescence but we have previously reported in utero smoking, breastfeeding, and birth weight were associated with bone mass at age 8.

METHODS

Birth weight, breastfeeding intention and habit, and maternal smoking during pregnancy were assessed at phase one in 1988-1999 and by recall during phase two in 1996-1997. Bone mineral density (BMD) was measured by dual-energy X-ray densitometry. Fractures were assessed by questionnaire. Subjects included 415 male and female adolescents from Southern Tasmania representing 29 % of those who originally took part in a birth cohort study in 1988 and 1989.

RESULTS

Breastfeeding (assessed in a number of ways) was associated with a 2-3 % increase in BMD at all sites apart from the radius and around a one third reduction in fracture risk which persisted after adjustment for confounders. In univariate analysis, birth weight was associated with BMD at the hip, radius, and total body but this did not persist in multivariate analysis and there was no association with fracture. Smoking in utero had no association with BMD at any site or fracture.

CONCLUSIONS

Breastfeeding is associated with a beneficial increase in bone mass at age 16 and a reduction in fracture risk during adolescence. The association previously observed at 8 years of age is no longer present for birth weight or smoking in utero.

Bone status and associated factors measured by quantitative ultrasound in preterm and full-term newborn infants

BACKGROUND

A clear understanding of the factors associated with bone status in newborn infants is essential for devising strategies for preventing osteoporotic fracture in future generations.

OBJECTIVE

The aims of this study were to perform bone speed of sound (SOS) to assess the status of the tibia in preterm and full-term newborns, and to evaluate factors associated with bone status at birth.

STUDY DESIGNS

Bone SOS was measured by quantitative ultrasonography on the left tibia in full-term and preterm newborn infants immediately after birth. A birth chart and maternal history were recorded. Univariate and multivariate analyses were performed to identify factors affecting bone SOS at birth.

SUBJECTS

The study analyzed 667 infants, including 370 males and 297 females, during study period.

RESULTS

Univariate analysis revealed that gender, gestational age (GA) and birth anthropometrics significantly affected tibial bone SOS at birth whereas maternal factors did not. Multivariate multiple regression analysis revealed that gender (male-to-female coefficient of 45.71 and 32.52 in premature and full-term infants, respectively), GA (coefficient of 32.55 and 31.27 in premature and full-term infants, respectively, for every 1-week increase), and birth weight (coefficient of -0.11 and -0.103 in premature and full-term infants, respectively, for every 1-gram increase) were important factors affecting tibial bone SOS in both preterm and full-term newborn infants at birth.

CONCLUSIONS

Male gender and advanced GA have a positive effect on increasing tibial bone SOS at birth, while birth weight had a negative effect on increasing tibial bone SOS. Tibial bone SOS is higher in small-for-gestational-age infants than in those of appropriate-for-gestational-age infants.

MAVIDOS Maternal Vitamin D Osteoporosis Study: study protocol for a randomized controlled trial. The MAVIDOS Study Group

MAVIDOS is a randomised, double-blind, placebo-controlled trial (ISRCTN82927713, registered 2008 Apr 11), funded by Arthritis Research UK, MRC, Bupa Foundation and NIHR.

Exposure to antiretroviral agents during pregnancy does not alter bone status in infants

The use of combined antiretroviral agents during pregnancy is important to prevent mother-to-child transmission of human immunodeficiency virus (HIV). Antiretroviral treatment (ARV) is associated with reduced bone mass and altered bone metabolism in HIV-infected patients. There are no data regarding the effect of ARV exposure during pregnancy on newborns and infants. We therefore studied 38 subjects born from HIV-infected mothers, and we measured the speed-of-sound (SOS) at the tibia by quantitative ultrasonography (QUS) just after birth. QUS measurements at mid-tibia is easily performed in infants with the appropriate probe. Nevertheless, at this skeletal site only cortical bone is present, and therefore QUS measurements reflect the status of only one kind of bone tissue. We also measured bone alkaline phosphatase (BAP) and C-terminal telopeptide of type I collagen (CTX) in the cord blood as bone formation and resorption markers, respectively. SOS measurements were repeated at 4 and 12 months of age. As a control group we studied 94 subjects born from HIV-negative mothers. At birth the median (range) SOS of ARV-exposed neonates was 3006 (2870-3168) m/s, while that of control subjects was 3007 (2757-3311) m/s. The difference was not significant. BAP concentration of ARV-exposed was 103.6 (31.6-182.8) U/L, not different from that of control subjects (104.4 [43.2-227.2] U/L). CTX concentrations were 1.07 (0.26-2.8) ng/mL, and 1.38 (0.34-4.2) ng/mL in ARV-exposed and control subjects, respectively. SOS measurements at 4 months and 12 months of age were available for 17 ARV-exposed subjects and for 57 control subjects. SOS values changed significantly over time in both groups (F=6.1; P<0.0001). No differences were present between ARV-exposed and control subjects at 4 and 12 months. Our study suggests that ARV exposure during intrauterine life does not affect negatively bone metabolism and bone development, and that the changes occurring in bone QUS measurements during the first year of life in ARV-exposed subjects are similar to those occurring in healthy control infants.

Association between passive smoking in adulthood and phalangeal bone mineral density: results from the KRAM study--the Danish Health Examination Survey 2007-2008

The study investigates an association between phalangeal bone mineral density (BMD) and self-reported passive smoking using data on 15,038 persons (aged 18-95 years), who underwent a BMD scan in the Danish KRAM study. BMD was significantly lower in persons exposed to long-term passive smoking in their home during adulthood.

INTRODUCTION

Smoking is associated with decreased bone mineral density (BMD) and increased risk of osteoporotic fractures. This study aimed to investigate a possible association between BMD at the phalangeal bones and self-reported passive smoking.

METHODS

The study included a cohort of 15,544 men and women aged 18-95 years, who underwent a BMD scan in the Danish KRAM study. BMD scans of the middle phalanges of the second, third and fourth digits of the non-dominant hand were performed with a compact radiographic absorptiometry system (Alara MetriScan®). Also, height, weight and body fat percentage were measured and 96.7% (n = 15,038) of the participants answered a self-reported questionnaire with information on passive smoking, other lifestyle factors, education, etc. The association between passive smoking and BMD was examined using multiple linear regression analysis.

RESULTS

A total of 39.1% (n = 5,829) of the participants had been exposed to passive smoking in adulthood at home. BMD was significantly lower in subjects exposed to passive smoking, 0.343 vs. 0.331 g/cm(2); p < 0.01 (unadjusted) and 0.339 vs. 0.337 g/cm(2); p < 0.05 (adjusted for age, gender, height and weight, and smoking). Multiple linear regression analysis showed that exposure to passive smoking for more than 20 years in adulthood at home was significantly related to BMD when adjusted for potential confounders (men, β = -4.4 × 10(-3); r = -0.05; p < 0.01 and women, β = -2.3 × 10 (-3); r = -0.03; p < 0.05). This relationship was also seen in the group of never smokers (β = -3.3 × 10(-3); r = -0.03; p = 0.01).

CONCLUSION

Our study supports a potential negative effect of long-term passive smoking in adulthood at home on phalangeal BMD.

Parental smoking during pregnancy and offspring bone mass at age 10 years: findings from a prospective birth cohort

We investigated an intrauterine influence of maternal smoking during pregnancy on childhood bone mass. Daughters, but not sons, of mothers who smoked had higher bone mass at age 10years. This appears to be due to familial factors related to parental smoking influencing increased offspring adiposity rather than a direct intrauterine effect.

INTRODUCTION

Neonatal studies have demonstrated an adverse relationship between maternal smoking in pregnancy and foetal bone mineral accrual. We aimed to investigate an intrauterine influence of maternal smoking during pregnancy on offspring bone mass at mean age 9.9 years.

METHODS

We compared associations of maternal and paternal smoking in pregnancy with offspring total body less head (TBLH) and spine bone mineral content (BMC), bone area (BA), bone mineral density (BMD) and area-adjusted BMC (ABMC) in 7,121 children in the Avon Longitudinal Study of Parents and Children.

RESULTS

Maternal smoking in any trimester was associated with increased TBLH BMC, BA and BMD in girls (mean difference [95% CI] (sex-specific SD scores), 0.13 [0.05-0.22], 0.13 [0.04-0.21], 0.13 [0.04-0.22], respectively) but not boys (0.01 [-0.07-0.09], 0.00 [-0.08-0.08], 0.04 [-0.05-0.12]), and also with spine BMC, BA and BMD in girls (0.13 [0.03-0.23], 0.12 [0.03-0.22], 0.10 [0.00-0.21]) but not boys (0.03 [-0.06-0.12], 0.00 [-0.09-0.09], 0.05 [-0.04-0.14]), but not with ABMC. Paternal smoking associations were similar, with no statistical evidence for a difference between maternal and paternal effects. Maternal associations increased on adjustment for offspring birth weight and gestational age, but attenuated to the null after adjustment for current height and weight.

CONCLUSIONS

We found little evidence that maternal smoking was related to bone mass in boys. In girls, maternal smoking associations were similar to those of paternal smoking, suggesting that these were attributable to shared familial characteristics, not intrauterine mechanisms.

Vitamin D status in pregnant Indian women across trimesters and different seasons and its correlation with neonatal serum 25-hydroxyvitamin D levels

The present cross-sectional study was conducted to determine the vitamin D status of pregnant Indian women and their breast-fed infants. Subjects were recruited from the Department of Obstetrics, Armed Forces Clinic and Army Hospital (Research and Referral), Delhi. A total of 541 apparently healthy women with uncomplicated, single, intra-uterine gestation reporting in any trimester were consecutively recruited. Of these 541 women, 299 (first trimester, ninety-seven; second trimester, 125; third trimester, seventy-seven) were recruited in summer (April–October) and 242 (first trimester, fifty-nine, second trimester, ninety-three; third trimester, ninety) were recruited in winter (November–March) to study seasonal variations in vitamin D status. Clinical, dietary, biochemical and hormonal evaluations for the Ca–vitamin D–parathormone axis were performed. A subset of 342 mother–infant pairs was re-evaluated 6 weeks postpartum. Mean serum 25-hydroxyvitamin D (25(OH)D) of pregnant women was 23·2 (sd 12·2) nmol/l. Hypovitaminosis D (25(OH)D < 50 nmol/l) was observed in 96·3 % of the subjects. Serum 25(OH)D levels were significantly lower in winter in the second and third trimesters, while serum intact parathormone (iPTH) and alkaline phosphatase levels were significantly higher in winter in all three trimesters. A significant negative correlation was found between serum 25(OH)D and iPTH in mothers (r − 0·367, P = 0·0001) and infants (r − 0·56, P = 0·0001). A strong positive correlation was observed between 25(OH)D levels of mother–infant pairs (r 0·779, P = 0·0001). A high prevalence of hypovitaminosis D was observed in pregnancy, lactation and infancy with no significant inter-trimester differences in serum 25(OH)D levels.

The morphology and mineralization of dental hard tissue in the offspring of passive smoking rats

OBJECTIVE

To study the effects of maternal passive smoking on the morphology and mineralization of dental hard tissue in offspring rats.

DESIGN

We have established a maternal passive smoking model. Offspring rats were sacrificed on the 20th day of gestation (E20) or the 3rd (D3) or 10th day (D10) after birth. We observed hard tissue morphology using Haematoxylin-Eosin (H&E) staining sections, used micro computer tomography (Micro-CT) to measure hard tissue thickness and volume on the mandibular first molars of the offspring rats, and used Micro-CT and energy dispersive X-ray spectroscopy with scanning electron microscopy (SEM/EDS) to determine the hard tissue mineral density and the ratio of calcium atom number/calcium atom+phosphorus atom number (Ca(2+)/P(3-)+Ca(2+)).

RESULTS

Overall, the development of dental hard tissue was delayed in the offspring of passive smoking rats. The thickness and volume of hard tissue were lower in the offspring of the maternal passive smoking group than in the offspring of the control group. Mineral density of the hard tissue and the ratio of (Ca(2+)/P(3-)+Ca(2+)) were also reduced in the offspring of the maternal passive smoking group.

CONCLUSION

Maternal passive smoking inhibits the morphological development and mineralization level of hard tissue on the mandibular first molars of offspring rats.

Maternal smoking and the vitamin D-parathyroid hormone system during the perinatal period

OBJECTIVE

To evaluate the effect of smoking on the vitamin D-parathyroid hormone (PTH) system during the perinatal period.

STUDY DESIGN

Sixty-one healthy women with singleton pregnancies and their newborns participated in a cohort study. We compared serum PTH and BsmI polymorphism of the vitamin D receptor gene, 25 hydroxyvitamin D (25(OH)D), 1,25 dihydroxyvitamin D, calcium, phosphorus, and bone alkaline phosphatase (bALP) in a smoking group (n = 32) versus a non-smoking group (n = 29), controlling for lifestyle confounders. The mothers were examined at 30 to 32 weeks and 38 to 40 weeks of pregnancy, and the infants were examined at 2 to 3 days of postnatal life.

RESULTS

Mothers who smoked and their newborns showed decreased serum PTH (30-32 weeks, 26.9 +/- 10.7 pg/mL versus 37.1+/-19.5 pg/mL; 38-40 weeks, 32.2 +/- 13.5 pg/mL versus 46.2 +/- 21.9 pg/mL, P = .005; newborns, 43.4 +/- 21.8 versus 64.1 +/- 34.2 pg/mL, P = .02) and increased phosphorus. Newborns of mothers who smoked also had significantly lower anthropometric measurements and serum 25(OH)D (14.2 +/- 6.2 ng/mL versus 22.3 +/- 11.3 ng/mL, P = .009). In addition, pregnant women who smoked had lower bALP (30-32 weeks, 31 +/- 15 U/L versus 44+/-29 U/L; 38-40 weeks, 55 +/- 32 U/L versus 97 +/- 62 U/L, P = .005).

CONCLUSIONS

Smoking during pregnancy negatively influences calcium-regulating hormones, leading to relative hypoparathyroidism in both the mother and their newborns.

Maternal smoking during pregnancy and child overweight: systematic review and meta-analysis

OBJECTIVE

Perform a systematic review of studies reporting on the association between maternal prenatal cigarette smoking and child overweight.

DESIGN

Meta-analysis of observational studies.

DATA SOURCES

Medline search and review of reference lists among studies published through June 2006.

REVIEW METHODS

Included studies reported an association between maternal smoking during pregnancy and risk of overweight among children at least 2 years of age. We did not include in the meta-analysis studies that provided only a continuous measure of adiposity, although those studies are discussed separately.

RESULTS

Based on results of 84 563 children reported in 14 observational studies, children whose mothers smoked during pregnancy were at elevated risk for overweight (pooled adjusted odds ratio (OR) 1.50, 95% CI: 1.36, 1.65) at ages 3-33 years, compared with children whose mothers did not smoke during pregnancy. The pooled estimate from unadjusted odds ratios (OR 1.52, 95% CI: 1.36, 1.69) was similar to the adjusted estimate, suggesting that sociodemographic and behavioral differences between smokers and nonsmokers did not explain the observed association. Although we observed evidence for publication bias, simulating a symmetric set of studies yielded a similar estimate (OR 1.40, 95% CI: 1.26, 1.55).

CONCLUSIONS

Prenatal smoking exposure appears to increase rates of overweight in childhood. In parts of the world undergoing the epidemiologic transition, the continuing increase in smoking among young women could contribute to spiraling increases in rates of obesity-related health outcomes in the 21st century.

Are birth weight and maternal smoking during pregnancy associated with malnutrition and excess weight among school age children?

In the late 1980's child malnutrition was still prevalent in Brazil, and child obesity was beginning to rise in the richest regions of the country. To assess the extent of the nutritional transition during the period and the influence of birth weight and maternal smoking on the nutritional condition of schoolchildren, we estimated the prevalence of excess weight and malnutrition in a cohort of Brazilian schoolchildren from 1987 to 1989. We calculated the body mass index (BMI) of 8- to 10-year-old schoolchildren born in Ribeirão Preto in 1978/79. We considered children with a BMI <5th percentile (P5) to be malnourished, children with P5 > or = BMI<P85 to be thin and normal, and children with BMI > or = P85 to be overweight. We evaluated the association of these nutritional disorders with birth factors (infant weight, sex, preterm delivery, number of pregnancies, maternal smoking during pregnancy, marital status, and schooling) and type of school using nominal logistic regression. A total of 2797 schoolchildren were evaluated. There was a significant prevalence of malnutrition (9.5%) and excess weight already tended to increase (15.7%), while 6.4% of the children were obese. Excess weight was more prevalent among children attending private schools (odds ratio, OR = 2.27) and firstborn children (OR = 1.69). Maternal smoking during pregnancy protected against malnutrition (OR = 0.56), while children with lower birth weight were at higher risk for malnutrition (OR = 4.23). We conclude that a nutritional transition was under way while malnutrition was still present, but excess weight and related factors were already emerging.

Genetic regulation of femoral bone mineral density: complexity of sex effect in chromosome 1 revealed by congenic sublines of mice

The findings that sex-specific effects on femoral structure and peak bone mineral density (BMD) are linked to quantitative trait loci (QTL) provide evidence for the involvement of specific genes that contribute to gender variation in skeletal phenotype. Based on previous findings that the BMD QTL in chromosome 1 (Chr 1) exerts a sex-specific effect on femoral structure, we predicted that congenic sublines of mice that carry one or more of the Chr 1 BMD loci would exhibit gender difference in the volumetric BMD (vBMD) phenotype. To test this hypothesis, we compared skeletal parameters of male and female of five C57BL/6J (B6).CAST/EiJ (CAST)-1 congenic sublines of mice that carry overlapping CAST chromosomal segments from the vBMD loci in Chr 1. Femur vBMD measurements were performed by the peripheral quantitative computed tomography in male and female mice at 16 weeks of age. The skeletal phenotype of the C175-185 and C178-185 congenic sublines of mice provided evidence for the presence of the BMD1-4 locus at 178-180 Mb from the centromere. This QTL affects femur vBMD only in female mice. In contrast, CAST chromosomal region carrying BMD1-1 locus increased femur vBMD both in male and female mice. Furthermore, a gender specific effect on BMD of femur mid-shaft region (mid-BMD) was identified at 168-176 Mb in Chr 1 (F=16.49, P=0.0002), while no significant effect was found on total femur BMD (F=2.67, P=0.11). Moreover, this study allowed us to locate a body weight QTL at 168-172 Mb of Chr 1, the effect of this locus was altered in female mice that carry CAST chromosomal segment 168-176 Mb of Chr 1. Based on this study, we conclude that Chr 1 carries at least two vBMD gender-dependent loci; one genetic locus at 178-180 Mb (BMD1-4 locus) which affects both mid-shaft and total femur vBMD in female mice only, and another gender-dependent locus at 168-176 Mb (BMD1-2 locus) which affects femur mid-shaft vBMD in female but not male mice.

Course of growth during the first 6 years in children exposed in utero to tobacco smoke

OBJECTIVES

Postnatal growth in children exposed in utero to tobacco smoke is not well understood. This study investigated growth during the first 6 years in children whose mothers smoked during pregnancy.

MATERIALS AND METHODS

Weight, length, and head circumference were measured annually for 6 years in 100 children in each group of smoking (study) and nonsmoking (control) mothers.

RESULTS

Weight and head circumference were significantly smaller in the neonates whose mothers smoked >or=15 cigarettes/day, but the difference disappeared by 3 years of life. Length was significantly smaller in the study neonates at birth, followed by increasing divergence from normality up to 2 years, when the mean difference of children whose mothers smoked >or=15 cigarettes/day from control children was -3.4 cm (p <or= 0.0001). Subsequently, they manifested catch-up growth ,and the difference from the controls at 3, 4, 5, and 6 years was -2.5 cm (p <or= 0.0001), -2.2 cm (p = 0.005), -2.1 cm (p = 0.013), and -1.9 cm (p = 0.055), respectively.

DISCUSSION

The delayed growth was related to smoking per se and appeared to be independent of several confounding factors. At birth, there was a significant negative correlation between the number of cigarettes smoked per day and the growth parameters studied; it remained significant up to the 6 year only for length.

CONCLUSION

Length exhibits the most persistent growth delay of the parameters studied, but catch-up growth occurs after the second year of life, and thus, intrauterine exposure to tobacco smoke seems to have no permanent effect on children's growth.

Infant programming of bone size and bone mass in 10-year-old black and white South African children

In developed countries, the earliest of factors shown to identify those at a high risk of having low bone mass and so be prone to osteoporosis in later life is that of quality of early life reflected by low birthweight (BW) and size in infancy. It is unclear whether such relationships exist in developing countries and in black populations. Associations were studied between BW, weight (WT1) and length (LT1) at 1 year and bone size and bone mass in 476 children (boys: 182 black, 72 white; girls: 158 black, 64 white) aged 10 years, who formed part of a longitudinal cohort of children born in Johannesburg, South Africa, during 1990. Bone area (BA) and bone mineral content (BMC) measurements were made of the whole body, femoral neck and lumbar spine (L1-L4) by dual-energy X-ray absorptiometry (DXA). After adjusting BA and BMC for race, gender, age, socio-economic status, bone age, height and weight at 10 years, on which BA and BMC in children are so dependent, WT1, LT1 and BW were significant predictors of whole body BA (WT1, P < 0.0001; LT1, P < 0.01; BW, P < 0.05) and BMC (WT1, P < 0.01; LT1, P < 0.05; BW, P < 0.05) and of BMC of the femoral neck (WT1, P < 0.01; LT1, P < 0.05). When BMC was in addition corrected for BA, then BW, WT1 and LT1 were predictive of femoral neck BMC (BW, P < 0.05; WT1, P < 0.05; LT1, P < 0.01) but not whole body BMC. Thus, BMC at 10 years appears to be independently associated with weight and length at 1 year, which is not completely mediated by the tracking of skeletal growth. Low BW and small size at 1 year resulted in smaller bones and/or bones of lower BMC at the femoral neck. The findings support the hypothesis that growth and development, both intrauterine and in the first year, which are measures of genetic, intrauterine and postnatal environmental factors, may have long-term consequences when compromised, and may be associated with the risk of osteoporosis in later life.

Fractures and recurrent fractures in children; varying effects of environmental factors as well as bone size and mass

BACKGROUND

Fractures are frequent in childhood and cause considerable morbidity. Previous reports have indicated a variety of potential contributors to fracture risk including low bone mineral content and density, milk avoidance, lack of exercise, asthma, obesity, and a high consumption of carbonated beverages.

AIMS

We wished to test the hypothesis that children who sustain recurrent fractures have a lower bone mass and a higher prevalence of underlying risk factors for fracture than those who fracture once or not at all.

METHODS

We studied 150 children aged 4-16 years: 50 who had suffered recurrent fractures, 50 who had fractured for the first time, and 50 fracture-free controls. Subjects underwent assessment of bone size and mass by total body (TB) and lumbar spine (L2-4) dual energy X-ray absorptiometry (DXA). Values were adjusted for body size, based on the control group measurements as unadjusted DXA values are substantially influenced by size in children. Anthropometry and grip dynamometry were carried out, and information about factors implicated in fracture aetiology such as milk intake, physical activity levels, asthma prevalence and carbonated beverage consumption were recorded using questionnaires.

RESULTS

Children who had sustained one or more fractures had a significantly lower BMC and aBMD at all sites than controls after conversion to size adjusted z scores (L2-4 BMC P = 0.0002; L2-4 aBMD P < 0.0001; TB BMC P < 0.0001; TB aBMD P < 0.0001); estimates for TB excluded fracture sites. There was, however, no difference in adjusted bone mass between children with one and those with recurrent fractures. Children with recurrent fractures had a significantly lower milk intake, lower levels of physical activity, a higher BMI, and a higher consumption of carbonated beverages than controls. The prevalence of risk factors was not, however, significantly higher than controls in children with a single fracture.

CONCLUSIONS

Children with fractures have a lower bone mass for body size than children without fractures. Modifiable risk factors such as diet and exercise increase the risk of recurrent fractures.

Maternal and early life influences on calcaneal ultrasound parameters and metacarpal morphometry in 7- to 9-year-old children

We investigated the relationship between maternal and early life influences, calcaneal ultrasound parameters, and metacarpal morphometry in 7- to 9-year-old children (n = 109) of mixed ancestral origin from a working class community. Their mothers had participated in a nutrition and pregnancy study at the time of the birth. Demographic and maternal data were collected. Anthropometry was assessed. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) were measured in the children and a subsample of the mothers (n = 94), using calcaneal ultrasound. Hand radiographs were used to measure metacarpal morphometry. There was no relationship between the ultrasound parameters, birthweight, current weight, or height. The ponderal index was correlated with BUA (r = 0.25; P = 0.036). BUA was lower in children whose mothers smoked during pregnancy compared to children whose mothers did not smoke (P = 0.054). Children whose mothers consumed alcohol during pregnancy had a lower Barnett-Nordin metacarpal index compared to children whose mothers did not consume alcohol (P < 0.05), after covarying for sex, age, gestational age, weight, and height of the child. Children's BUA was negatively correlated with housing density (r = -0.23; P = 0.021). In this study, we found an association between maternal and early life influences on calcaneal ultrasound parameters and metacarpal morphometry in prepubertal children, an association that was also influenced by sociodemographic and environmental factors.