This study examined associations between pregnancy and infant birth outcomes with child telomere length at age 17 years; and investigated if there are sex differences between pregnancy complications and telomere length. We utilised the population-based prospective Raine cohort study in Western Australia, Australia. 2900 pregnant women were recruited at 16–20 weeks’ gestation (Gen 1), and their children (Gen 2) were followed up over several years. Generalised linear models were used to examine relationships between pregnancy or birth outcomes (gestational diabetes, pre-eclampsia, preterm birth, low birth weight, macrosomia), and as a composite, with telomere length, measured via a DNA sample from blood at 17 years of age. Analyses were adjusted for a range of confounders. Among the 1202 included children, there were no differences in child telomere length for any of the individual maternal or birth weight pregnancy outcomes nor were there any significant interactions between each of the complications (individual or composite) and the sex of the child. However, females born from any of the 5 adverse outcomes had shorter telomeres (estimated mean (SE) = -0.159 (0.061), p = 0.010) than females born in the absence of these complications. Specifically, females born from a pre-eclamptic pregnancy had shorter telomeres than females not born from a pre-eclamptic pregnancy (estimated mean (SE) = -0.166 (0.072), p = 0.022). No relationships were observed in males. Further longitudinal studies are needed to understand mediating factors that are important in predicting offspring telomere length and the necessity to investigate females and males independently.

Depression is a major cause of disability in adolescents. Higher dietary fibre intake has been associated with lower depressive symptoms in adults, but there is a lack of research in adolescents. We examined the association between dietary fibre intake (Commonwealth Scientific and Industrial Research Organisation (CSIRO) FFQ) and depressive symptoms (Beck Depression Inventory for Youth) in adolescents with prospective data from the Raine Study Gen2 14- and 17-year follow-ups (n 1260 and 653). Odds of moderate/extreme (clinically relevant) depressive symptoms by quartile of fibre intake were calculated using mixed-effects logistic regression for all participants, in a paired sample without moderate/extreme depressive symptoms at 14 years and in a sub-sample of participants with available inflammatory data at the ages of 14 and 17 years (n 718 and 547). Odds of moderate/extreme depressive symptoms were lower in the fourth (highest) quartile of overall fibre intake (OR 0·273, 95 % CI 0·09, 0·81) compared with the first (lowest) quartile, adjusting for sex, age, energy intake, adiposity, and family and lifestyle factors. However, further adjustment for dietary patterns attenuated the results. Associations of depressive symptoms with cereal or fruit and vegetable fibre intake were not significant in the final model. Adjustment for inflammation had no effect on OR. The association between a higher dietary fibre intake and lower odds of clinically relevant depressive symptoms may be more reflective of a high-fibre diet with all its accompanying nutrients than of an independent effect of fibre.

A high dietary fibre intake has been associated with improvements in inflammatory conditions in adults. However, little is known on whether associations between dietary fibre and inflammation are evident during adolescence. We examined the relationship between dietary fibre intake measured by FFQ and the inflammatory marker high-sensitivity C-reactive protein (hs-CRP) and the adipokines leptin and adiponectin cross-sectionally in 17-year-olds participating in the Raine Study (n 621). In weighted analysis using tobit and linear regression, and after excluding participants with hs-CRP > 10 mg/l, higher total dietary fibre intake (per 5 g/d) was significantly associated with lower leptin (β = –0·13, 95 % CI –0·17, –0·09) and adiponectin (β = –0·28, 95 % CI –0·49, –0·07), but not hs-CRP, in unadjusted analyses. These associations were no longer significant after adjustment for sex, anthropometry and a number of lifestyle factors. However, higher cereal and grain fibre intake was significantly associated with lower leptin (β = –0·06, 95 % CI –0·10, –0·01) in fully adjusted analysis. Our findings suggest that a higher intake of cereal and grain fibre may contribute to lower leptin in adolescents. This may contribute to reductions in low-grade chronic inflammation and improved health outcomes.

The long-term adherence to the dietary guidelines has not been evaluated against emergence of cardiometabolic risks in adolescents with increasing rates of obesity. The present study aimed to (1) determine the level of adherence to the guidelines using the Australian Dietary Guideline Index for Children and Adolescents (DGI-CA) in adolescents of age 14 and 17 years and to (2) examine the relationship between their assessed diet quality and concurrently measured cardiometabolic risk factors over time. Data were analysed from the Western Australian Pregnancy Cohort (Raine) Study. The DGI-CA was determined from a FFQ. Anthropometry and fasting biochemical measures were taken using standard procedures. Hierarchical linear mixed models examined associations between cardiometabolic risk factors and DGI-CA, adjusting for socio-economic status, physical activity, BMI, and sex, and examining for interactions. The mean DGI-CA scores were 47·1 (sd 10·2) at 14 years (n 1419) and 47·7 (sd 11·0) at 17 years (n 843), and were not different between sex. There was a significant inverse association between DGI-CA and insulin, homeostasis model assessment score and heart rate. The DGI-CA was positively associated with BMI (P= 0·029) but negatively with waist:hip ratio (P= 0·026). It was not associated with lipids or blood pressure, with the exception of a negative association with TAG (P= 0·011). The degree of adherence in the Raine Study adolescents was suboptimal but similar to the Australian Children's Nutrition and Physical Activity Survey. The present study shows that, at any particular time, better diet quality was associated with better insulin sensitivity and TAG levels and decreased abdominal fatness.

Almost all previous studies examining the associations between glycaemic load (GL) and metabolic syndrome risk have used a daily GL value. The daily value does not distinguish between peaks of GL intake over the day, which may be more closely associated with the risk of the metabolic syndrome. The aim of the present study was to investigate the cross-sectional associations between daily and mealtime measures of GL and metabolic syndrome risk, including metabolic syndrome components, in adolescents. Adolescents participating in the 14-year follow-up of the Western Australian Pregnancy Cohort (Raine) Study completed 3 d food records and metabolic assessments. Breakfast GL, lunch GL, dinner GL and a score representing meal GL peaks over the day were determined in 516 adolescents. Logistic regression models were used to investigate whether GL variables were independent predictors of the metabolic syndrome in this population-based cohort (3·5 % prevalence of the metabolic syndrome). Breakfast GL was found to be predictive of the metabolic syndrome in girls (OR 1·15, 95 % CI 1·04, 1·27; P <0·01), but not in boys. Other meal GL values and daily GL were found to be not significant predictors of the metabolic syndrome. When breakfast GL was examined in relation to each of the components of the metabolic syndrome in girls, it was found to be negatively associated with fasting HDL-cholesterol concentrations (P= 0·037; β = − 0·004; 95 % CI − 0·008, − 0·002) and positively associated with fasting TAG concentrations (P= 0·008; exp(β) = 1·002; 95 % CI 1·001, 1·004). The results of the present study suggest that there may be an association between breakfast composition and metabolic syndrome components in adolescent girls. These findings support further investigation into including lower-GL foods as part of a healthy breakfast in adolescence, particularly for girls.

Despite the importance of skeletal growth during adolescence, there is limited research reporting vitamin D status and its predictors in adolescents. Using prospective data from the Western Australian Pregnancy Cohort (Raine) Study, we investigated vitamin D status and predictors of serum 25-hydroxyvitamin D (25(OH)D) concentrations in adolescents. Serum 25(OH)D concentrations were measured in the same participants at 14 and 17 years (n 1045 at both time points). The percentage of adolescents with serum 25(OH)D concentrations < 50, 50–74·9 and ≥ 75 nmol/l was reported year-round and by month of blood collection. We examined the predictors of serum 25(OH)D concentrations, including sex, race, month of blood collection, physical activity, BMI, family income, and Ca and vitamin D intakes (n 919 at 14 years; n 570 at 17 years), using a general linear mixed model. At 14 years, 31 % of adolescents had serum 25(OH)D concentrations between 50 and 74·9 nmol/l and a further 4 % had concentrations < 50 nmol/l. At 17 years, 40 % of adolescents had serum 25(OH)D concentrations between 50 and 74·9 nmol/l and 12 % had concentrations < 50 nmol/l. Caucasian ethnicity, being sampled at the end of summer, exercising more, having a lower BMI, a higher Ca intake and a higher family income were significantly associated with higher serum 25(OH)D concentrations. The proportion of adolescents with serum 25(OH)D concentrations < 50 nmol/l was low in this Western Australian cohort. There is a need for international consensus on defining adequate vitamin D status in order to determine whether strategies to increase vitamin D status in adolescents are warranted.

Despite the increasing use of dietary patterns (DP) to study diet and health outcomes, relatively few studies have examined the reliability of DP using different dietary assessment methods. Reduced-rank regression (RRR) is an emerging statistical method that incorporates a priori information to characterise DP related to specific outcomes of interest. The aim of the present study was to compare DP identified using the RRR method in a FFQ with those in a 3 d food record (FR). Participants were 783 adolescents from the Western Australian Pregnancy (Raine) Cohort Study who completed both a FFQ and FR at 14 years of age. A similar ‘energy-dense, high-fat and low-fibre’ DP was identified in the FFQ and FR that was characterised by high intakes of processed meat and sugar-sweetened beverages, and low intakes of vegetables and fresh fruit. Nutrient profiles for this DP were consistent in the FFQ and FR. Pearson's correlation coefficient between participants' z-scores for the DP identified in the FFQ and FR was 0·35 for girls and 0·49 for boys (P< 0·05). The mean difference between DP z-scores derived from the FFQ and FR was − 0·08 (95 % CI − 0·21, 0·04) for girls and − 0·05 (95 % CI − 0·17, 0·07) for boys. The 95 % limits of agreement were − 2·55 to 2·39 for girls and − 2·52 to 2·41 for boys. These findings suggest that very similar DP may be identified and their z-scores show modest agreement when applying the RRR method to dietary intake data collected from adolescents using a FFQ or FR.

Two pregnancy cohorts were used to investigate the association between single-nucleotide polymorphisms (SNPs) in genes within the insulin-like growth factor (IGF)-axis and antenatal and postnatal growth from birth to adolescence. Longitudinal analyses were conducted in the Raine pregnancy cohort (n = 1162) using repeated measures of fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) from 18 to 38 weeks gestation and eight measures of postnatal height and weight (1–17 years). Replications of significant associations up to birth were undertaken in the Generation R Study (n = 2642). Of the SNPs within the IGF-axis genes, 40% (n = 58) were associated with measures of antenatal growth (P ⩽ 0.05). The majority of these SNPs were in receptors; IGF-1R (23%; n = 34) and IGF-2R (13%; n = 9). Fifteen SNPs were associated with antenatal growth (either AC or HC or FL) in Raine (P ⩽ 0.005): five of which remained significant after adjusting for multiple testing. Four of these replicated in Generation R. Associations were identified between 38% (n = 55) of the IGF-axis SNPs and postnatal height and weight; 21% in IGF-1R (n = 31) and 9% in IGF-2R (n = 13). Twenty-six SNPs were significantly associated with both antenatal and postnatal growth; 17 with discordant effects and nine with concordant effects. Genetic variants in the IGF-axis appear to play a significant role in antenatal and postnatal growth. Further replication and new analytic methods are required in order to better understand this key metabolic pathway integrating biologic knowledge about the interaction between IGF-axis components.

Obesity has origins extending to antenatal and early postnatal periods; however, the relationship between early postnatal diet and subsequent obesity is not well defined. The aims of this study were to determine whether early childhood dietary quality was associated with (a) infant and adolescent nutrition and (b) body mass index (BMI) in childhood and adolescence. The degree to which early nutrition and growth factors determine BMI throughout childhood and adolescence was also explored. This research was conducted using the Raine Study, a longitudinal survey of Australian children assessed from mid-gestation to 17 years of age. A dietary quality index, the Raine Eating Assessment in Toddler score, was assigned to 2562 participants to assess early nutrition. Linear regression determined that breastfeeding was associated with dietary quality at 1–3 years. Dietary elements at 14 years of age were related to earlier dietary quality. There were no consistent associations between early diet and BMI at 3, 5, 8, 10, 14 or 17 years. In contrast, birth weight and infant weight gain were significantly associated with BMI at these ages. This study suggests that early dietary patterns are associated with aspects of diet in adolescence, likely reflecting the influence of maternal reporting. Birth weight and early growth appear to be more important determinants of adolescent BMI than early diet and nutrition. While optimizing early diet by maternal nutritional education has potential to influence later nutrition, interventions focussing on early weight gain may have a greater impact on the obesity epidemic.

Interest in empirically derived dietary patterns has increased over the past decade. However, relatively few studies have evaluated dietary patterns using different dietary methods, or in young populations. We quantitatively compared dietary patterns from a FFQ with those from a 3 d food record (FR) in a cohort of adolescents. Subjects from the Western Australian Pregnancy Cohort (Raine) Study completed a semi-quantitative FFQ and a 3 d FR at 14 years of age (n 783). Major dietary patterns were identified using exploratory factor analysis on thirty-eight food groups. Dietary pattern z-scores were compared using 95 % limits of agreement (LOA) and Spearman's r. Two major dietary patterns were identified in the FFQ and FR: a ‘Healthy’ pattern, which was high in fresh fruit, vegetables, whole grains and grilled or canned fish, and a ‘Western’ pattern, which was high in take-away foods, confectionery, soft drinks, crisps and fried potato. The nutrient profiles of these dietary patterns were similar when estimated by the FFQ and FR. The LOA between dietary pattern scores from the FFQ and FR were − 1·69 to 1·75 (‘Healthy’) and − 1·89 to 1·82 (‘Western’). Minor differences in agreement were observed when boys and girls were analysed separately. Spearman's correlation coefficients between the FFQ and the FR were r 0·45 (‘Healthy’) and r 0·36 (‘Western’). Comparable dietary patterns may be obtained from the FFQ and FR using exploratory factor analysis. This supports the use of major dietary patterns identified using the FFQ in this adolescent cohort.