Malcolm Riley

Maternal Smoking During Pregnancy, Growth, and Bone Mass in Prepubertal Children

There have been no studies of smoking during pregnancy and bone mineralization in children. The objective of this population‐based longitudinal study was to determine whether maternal smoking during pregnancy is associated with bone mass and other growth variables in prepubertal children. We studied 330 8‐year‐old male and female children representing 47% of those who originally took part in a study of risk factors for Sudden Infant Death Syndrome in 1988. The main outcome measures were bone mineral density measured by a Hologic QDR2000 densitometer: birth weight, placental weight, height, and weight. Maternal smoking during pregnancy was associated with deficits in growth with these children having lower height (−1.53 cm, 95% confidence interval [CI] −3.03 to −0.03) and a trend to lower weight (−1.35 kg, 95% CI −2.75 to 0.11) at age 8. Furthermore, there was a disproportionate deficit in bone mass such that those children whose mothers smoked during pregnancy had lower size adjusted bone mass at the lumbar spine (−0.019 g/cm2, 95% CI −0.033 to −0.005) and femoral neck (−0.018 g/cm2, 95%CI −0.034 to −0.002) but not total body (−0.005 g/cm2, 95% CI −0.015 to 0.005). This association was only present for children born at term. Mothers who smoked during pregnancy also had lower placental weight (− 56 g, 95% CI −95 to −17), and further adjustment for placental weight led to nonsignificant results for smoking with both growth and bone parameters, suggesting that these associations may be mediated through placental size and function. Maternal smoking habit in 1996 was not significantly associated with bone mass at any site. In conclusion, this study has demonstrated a long‐term negative association between maternal smoking during pregnancy and both growth and bone mass in children born at term, and suggests that the timing of exposure rather than the dose or duration is critical. If these associations are present in other populations and they persist until the attainment of peak bone mass, then our findings suggest that osteoporosis prevention programs should start very early in the life cycle.

Breastfeeding in early life and bone mass in prepubertal children: a longitudinal study.

Abstract: The aim of this study was to determine whether breastfeeding in early life is associated with bone mass in prepubertal children. We studied 330 8-year-old male and female children from Southern Tasmania representing 47% of those who originally took part in a birth cohort study of risk factors for Sudden Infant Death Syndrome in 1988. Breastfeeding intention and habit were assessed in both 1988 and 1996. Bone mineral density was measured by dual-energy X-ray densitometry. Children who were breastfed had higher bone mineral density at the femoral neck (+0.20 SD, p= 0.07), lumbar spine (+0.25 SD, p= 0.03) and total body (+0.29 SD, p= 0.006) compared with those who were bottle-fed. This association with breastfeeding was present in children born at term (femoral neck: +0.26 SD, p= 0.05; lumbar spine: +0.34 SD, p= 0.007; total body: +0.41 SD, p= 0.0008) but not those born preterm, and remained significant after adjustment for size, lifestyle factors and socioeconomic factors. Breastfeeding for less than 3 months was not associated with increased bone mass at any site. In conclusion, this study has demonstrated a beneficial association between breastfeeding in early life and bone mass in 8-year-old children born at term, particularly those breastfed for 3 months or longer, which appears biological. If this association is confirmed in other populations and persists until the attainment of peak bone mass then the implication would be that osteoporosis prevention programs need to start very early in the life cycle.

The effect on behavior and bone mineral density of individualized bone mineral density feedback and educational interventions in premenopausal women: a randomized controlled trial [NCT00273260]

BackgroundLimited information is available on ways to influence osteoporosis risk in premenopausal women. This study tested four hypotheses regarding the effects of individualized bone density (BMD) feedback and different educational interventions on osteoporosis preventive behavior and BMD in pre-menopausal women, namely: that women are more likely to change calcium intake and physical activity if their BMD is low; that group education will be more efficacious at changing behavior than an information leaflet; that BMD feedback and group education have independent effects on behavior and BMD; and, that women who improve their physical activity or calcium intake will have a change in bone mass over 2 years that is better than those who do not alter their behavior.MethodsWe performed a 2-year randomized controlled trial of BMD feedback according to T-score and either an osteoporosis information leaflet or small group education in a population-based random sample of 470 healthy women aged 25–44 years (response rate 64%). Main outcome measures were dietary calcium intake, calcium supplement use, smoking behavior, physical activity, endurance fitness, lower limb strength and BMD. We used paired t-tests, one-way ANOVA and linear regression techniques for data analysis.ResultsWomen who had feedback of low BMD had a greater increase in femoral neck BMD than those with normal BMD (1.6% p.a. vs. 0.7% p.a., p = 0.0001), but there was no difference in lumbar spine BMD change between these groups (0.1% p.a. vs. 0.08% p.a., p = 0.9). Both educational interventions had similar increases in femoral neck BMD (Leaflet = +1.0% p.a., Osteoporosis self-management course = + 1.3% p.a., p = 0.4). Femoral neck BMD change was only significantly associated with starting calcium supplements (1.3 % p.a, 95%CI +0.49, +2.17) and persistent self-reported change in physical activity levels (0.7% p.a., 95%CI +0.22, +1.22).ConclusionIndividualized BMD feedback combined with a minimal educational intervention is effective at increasing hip but not spine bone density in premenopausal women. The changes in behavior through which this was mediated are potentially important in the prevention of other diseases, thus measuring BMD at a young age may have substantial public health benefits, particularly if these changes are sustained.

Vitamin D levels in prepubertal children in Southern Tasmania: prevalence and determinants.

Objective: To describe the prevalence and determinants of 25-hydroxy D3(25(OH)D) in children.Design: Cross-sectional study.Setting: Southern Tasmania between June and November 1997.Subjects: Two hundred and one 8-y old male and female children taking part in a cohort study whose principal endpoints were blood pressure and high-density lipoprotein (HDL) cholesterol.Results: The mean 25(OH)D level was 79 nmol/l (s.d. 29.5, median 73, range 12–222). Boys had higher levels than girls (82.1 vs 72.8 nmol/l, P=0.02). 25(OH)D was associated with sunlight exposure in winter school holidays (r=0.20, P=0.005) and winter weekends (r=0.16, P=0.02), the month after school holidays (87.5 vs 69.5 nmol, P<0.0001) and body mass index (r=−0.23, P=0.001). Dietary intake of vitamin D was low (mean 40 IU/day, range 5.2–384) and was not associated with 25(OH)D levels (r=0.01, P=0.91). Variation in skin melanin density was weakly associated with 25(OH)D (r=0.09, P=0.19).Conclusions: Sunlight is the major determinant of vitamin D stores in our population. Neither variation in skin type within Caucasians nor diet modified this association to any significant extent. Extrapolation of these findings to sunlight bone mass associations in a very similar population suggests that a minimum level of around 50 nmol/l in the population is required for optimal bone development in prepubertal children but this needs to be confirmed with further controlled trials of vitamin D supplementation and bone mass.Sponsorship: Arthritis Foundation of Australia, Roche Pharmaceuticals.

Maternal diet during pregnancy is associated with bone mineral density in children: a longitudinal study.

Objective: To describe the association between maternal diet during the third trimester of pregnancy and bone mass in 8 y-old male and female children.Design: Longitudinal study.Setting: Southern Tasmania between 1988 and 1996.Subjects: One-hundred and seventy-three 8 -y-old male and female children with adequate maternal dietary information taking part in a study of bone mineralization.Results: After adjustment for confounders, femoral neck bone mineral density (BMD) was positively associated with magnesium and phosphorus density of the maternal diet; lumbar spine BMD was positively associated with magnesium, phosphorus and potassium and negatively associated with fat density while total body BMD was positively associated with magnesium, potassium and protein and negatively associated with fat density (all P<0.05). After further adjustment for other significant dietary factors, the only significant remaining associations observed were for phosphorus and fat at the lumbar spine, although the adjusted goodness of fit of the models improved compared to those including one dietary variable. A child in the ‘optimal’ levels of dietary exposures had significantly higher adjusted BMD at all sites (femoral neck, +5.5%, lumbar spine, +12%, total body, +6.8%). Calcium intake was not associated with BMD at any site, possibly due to a high average intake.Conclusions: This study reports a substantial association between in utero diet in a well-nourished population and later bone mass in their children. However, it does not allow identification of the dietary components of greatest importance, indicating that these results should be regarded as hypothesis-generating. Further longitudinal studies in other populations are required to confirm that dietary manipulation during pregnancy has a role to play in the early life prevention of osteoporosis.Sponsorship: National Health and Medical Research Council of Australia, Tasmanian Government and the Royal Hobart Hospital Acute Care Program.European Journal Of Clinical Nutrition (2000) 24, 749–756

The association between maternal diet during pregnancy and bone mass of the children at age 16

Background/Objectives:Fetal life may be a critical period for the development and/or programming of metabolic systems, including the skeleton. However, it is unclear on the association between maternal nutrition during pregnancy and bone mass in their offspring at adolescence.Subjects/Methods:This was a birth cohort study of 216 adolescents (16.2±0.4 years). Dietary intake was measured by food frequency questionnaire. Bone densitometry was measured at the femoral neck, lumbar spine and total body by DXA.Results:After adjustment for confounders, bone mineral density (BMD) of the femoral neck was positively associated with magnesium density and negatively associated with fat density (all P-values <0.05). BMD of the lumbar spine was positively associated with calcium, magnesium and phosphorus density and negatively associated with fat density (all P-values <0.05). Maternal milk intake was significantly positively associated with lumbar spine BMD. After considering all significant nutrients in the same model, fat density remained significant negatively for the femoral neck and lumbar spine, whereas magnesium density remained significant positively for the femoral neck. No nutrient was significant for the total body.Conclusions:Maternal intake of milk, fat and magnesium during the third trimester of pregnancy is predictive of BMD at age 16, suggesting that in utero diet influences peak bone mass possibly through programming bone responses.

Differences in HDL Cholesterol Concentrations in Japanese, American, and Australian Children

BACKGROUND Mortality from coronary heart disease is relatively low in Japan compared with other developed countries and has remained low despite an increasing standard of living and an apparent increase in mean plasma cholesterol concentration in adults over the past three decades. Important differences in childhood plasma lipoprotein profile might contribute to some of the difference in coronary heart disease mortality seen between Japan and both Australia and North America. METHODS AND RESULTS Plasma HDL cholesterol and total cholesterol were surveyed in representative populations of schoolchildren in Australia, Japan, and Bogalusa, La. The mean concentration of plasma HDL cholesterol (but not total cholesterol) was higher for Japanese schoolchildren than for Australian or US schoolchildren (P<.001). In addition, the difference in plasma HDL cholesterol between the ages of 8 to 10 years and 12 to 15 years was much greater for Australian (boys, 15.2%; girls, 2.6%) and US (boys, 9.1%; girls, 2.7%) children than for their Japanese counterparts (boys, 4.2%; girls, 1.9%). An examination of potential explanatory factors revealed little difference in body mass index between samples, higher physical activity levels for the Japanese compared with the Australians, and substantial differences in dietary intake between Japanese and Australian schoolchildren. CONCLUSIONS The relatively high ratio of plasma HDL cholesterol to total cholesterol in Japanese schoolchildren and the relatively small negative difference of plasma HDL cholesterol with age may help to explain why the coronary heart disease mortality rate in Japan is low compared with that in other developed countries.

Comparative Validity of a Food Frequency Questionnaire for Adults with IDDM

OBJECTIVE To investigate the characteristics of a food frequency questionnaire (FFQ) in measuring dietary intake in an adult insulin-dependent diabetes mellitus (IDDM) population. FFQs have been widely used in developed countries to assess usual dietary intake; however, information regarding the application of the method to individuals advised to follow a specific dietary regimen (such as people with IDDM) is scarce. RESEARCH DESIGN AND METHODS The measurement of energy and macronutrients by an interviewer-administered FFQ was assessed in 84 adults, who were representative of adults with IDDM in Tasmania, Australia, by comparing it with 2 days of weighed dietary records. Mean daily energy and macronutrient intakes by each method were compared, and Pearson correlation coefficients were calculated for both unadjusted and energy-adjusted macronutrient intakes. RESULTS The ratio of within-person to between-person variance in dietary estimates from weighed records was 0.53 for energy, 0.70 for fat, 2.55 for protein, 0.50 for carbohydrate, 0.78 for saturated fat, and 3.56 for dietary cholesterol. The correlation coefficient between the FFQ and a 2-day weighed dietary record for the same nutrients ranged from 0.38 for protein intake to 0.60 for saturated fat intake. The correlation coefficient between the FFQ and true usual dietary intake was estimated to be 0.60 for energy-adjusted fat intake, 0.36 for energy-adjusted protein intake, 0.72 for energy-adjusted carbohydrate intake, 0.55 for energy-adjusted saturated fat intake, and 0.77 for energy-adjusted cholesterol intake. CONCLUSIONS People with IDDM had a low ratio of within-person to between-person variance in daily energy, fat, carbohydrate, saturate fat, and cholesterol intake. The performance of the FFQ in the IDDM population is consistent with similar questionnaires in nondiabetic populations; however, there was a significant decrease in the dietary energy estimate upon readministration of the questionnaire. Validation studies such as this are important to provide information to guide the design and analysis of investigations that use dietary questionnaires.

Sociodemographic factors associated with calcium intake in premenopausal women: a cross-sectional study

Objective:To describe associations between sociodemographic factors and calcium intake in premenopausal women.Design:Cross-sectional study.Setting:Population-based.Subjects:A total of 467 randomly selected, predominantly Caucasian Tasmanian women aged 25–44 y, response rate 63%.Main outcome measures:calcium intake, sociodemographic factors, anthropometrics, osteoporosis knowledge and self-efficacy.Results:Education level, calcium-specific osteoporosis knowledge and self-efficacy were all independently associated with calcium intake (P<0.05). The odds of achieving the recommended dietary intake for calcium increased with higher levels of calcium-specific self-efficacy and knowledge, and decreased in smokers or if the households main financial provider was unemployed (P<0.05).Conclusions:Women who have lower levels of education, who are in households where the main financial provider is unemployed, who are smokers, and those with low levels of calcium-specific self-efficacy and knowledge are at risk of not achieving adequate calcium intake. This information will assist targeting of public health strategies aimed at improving the calcium intake of premenopausal women.Sponsorship:This study was supported by a National Health and Medical Research Council grant and the Government of Tasmania.

Water fluoridation, bone mass and fracture: a quantitative overview of the literature

Objective: To use the technique of metaanalysis to address the following research questions: Is water fluoridation associated with altered fracture risk at a population level and are the differences between studies consistent with confounding or chance variation between studies?