Predictors of obesity in childhood, adolescence, and adulthood in a birth cohort

Flexible models of change: using structural equations to match statistical and theoretical models of multiple change processes

OBJECTIVE

To introduce and illustrate recent advances in statistical approaches to simultaneous modeling of multiple change processes.

METHODS

Provide a general overview of how to use structural equations to simultaneously model multiple change processes and illustrate the use of a theoretical model of change to guide selection of an appropriate specification from competing alternatives. The selected latent change score model is then fit to data collected during an adolescent weight-control treatment trial.

RESULTS

A latent change score model is built starting with the foundation of repeated-measures analysis of variance and illustrated using graphical notation.

CONCLUSIONS

The assumptions behind using structural equations to model change are discussed as well as limitations of the approach. Practical guidance is provided on matching the statistical model to the theory underlying the observed change processes and the research question(s) being answered by the analyses.

BMI of the firstborn offspring at age 12 reflects maternal LDL and HDL cholesterol levels at term pregnancy and postpartum

OBJECTIVE

The aim of this study was to assess the relationship between the body mass index (BMI) of the firstborn offspring at age 12 and maternal lipid levels at term and at 6 months postpartum.

DESIGN AND METHODS

The study included children born in the 2nd Department of Obstetrics and Gynecology of the Medical University of Warsaw between 1 November 1991 and 31 May 1993. The end point was BMI in the upper quartile - considered high BMI of the firstborn offspring at age 12.

RESULTS

The risk of high BMI in the offspring at age 12 significantly increased with an increase in the LDL-C level at term (OR = 2.41 per SD increase, 95% CI: 1.01-5.80; p < 0.049), a decrease in the HDL-C% at term (OR = 0.35 per SD increase, 95% CI: 0.14-0.84; p < 0.019) and a decrease in the HDL-C level at 6 months postpartum (OR = 0.25 per SD increase, 95% CI: 0.08-0.82; p < 0.022), regardless of maternal weight status before pregnancy and at 6 months postpartum, gestational weight gain, the offspring's gender and birth weight.

CONCLUSION

LDL and HDL cholesterol levels at term are markers of maternal adaptation to a first pregnancy and predict the future growth of firstborn offspring.

Risk of childhood overweight or obesity associated with excessive weight gain during pregnancy: a meta-analysis

PURPOSE

Several investigations have shown that the risk of childhood overweight and obesity may be associated with excessive gestational weight gain (GWG), but the study samples were limited and results were mixed; hence we conducted this meta-analysis to assess the explicit association between them and present evidence.

METHODS

We searched PubMed, EMbase, Ovid, Web of knowledge and Cochrane library for relevant studies. Bibliographies from retrieved articles were also manually searched. Cohort studies that presented results by OR or RR with 95 % CI for the association of maternal excessive GWG and child overweight/obesity were included. The pooled estimates were calculated by fixed-effect model or random-effect model according to the heterogeneity.

RESULTS

Twelve cohort studies were identified, and the combined OR of excessive GWG and childhood overweight/obesity was 1.33 (95 % CI 1.18-1.50) with evidence of heterogeneity (P = 0.000, I (2) = 71.1 %). Adjustment of maternal BMI, investigation area, age of children, research type, and omission of any single study had little effect on the pooled estimate. After eliminating the effect of publication bias by trim and fill analyses, the result still remained statistically significant (OR 1.21, 95 % CI 1.05-1.40).

CONCLUSIONS

This meta-analysis suggests that the risk of childhood overweight/obesity is significantly associated with excessive gestational weight gain.

Prevalence and determinants of obesity among primary school children in Dar es Salaam, Tanzania

BACKGROUND

Childhood obesity has increased dramatically and has become a public health concern worldwide. Childhood obesity is likely to persist through adulthood and may lead to early onset of NCDs. However, there is paucity of data on obesity among primary school children in Tanzania. This study assessed the prevalence and determinants of obesity among primary school children in Dar es Salaam.

METHODS

A cross sectional study was conducted among school age children in randomly selected schools in Dar es Salaam. Anthropometric and blood pressure measurements were taken using standard procedures. Body Mass Index (BMI) was calculated as weight in kilograms divided by the square of height in meters (kg/m2). Child obesity was defined as BMI at or above 95th percentile for age and sex. Socio-demographic characteristics of children were determined using a structured questionnaire. Logistic regression was used to determine association between independent variables with obesity among primary school children in Dar es Salaam.

RESULTS

A total of 446 children were included in the analysis. The mean age of the participants was 11.1±2.0 years and 53.1% were girls. The mean BMI, SBP and DBP were 16.6±4.0 kg/m2, 103.9±10.3mmHg and 65.6±8.2mmHg respectively. The overall prevalence of child obesity was 5.2% and was higher among girls (6.3%) compared to boys (3.8%). Obese children had significantly higher mean values for age (p=0.042), systolic and diastolic blood pressures (all p<0.001). Most obese children were from households with fewer children (p=0.019) and residing in urban areas (p=0.002). Controlling for other variables, age above 10 years (AOR=3.3, 95% CI=1.5-7.2), female sex (AOR=2.6, 95% CI=1.4-4.9), urban residence (AOR=2.5, 95% CI=1.2-5.3) and having money to spend at school (AOR=2.6, 95% CI=1.4-4.8) were significantly associated with child obesity.

CONCLUSIONS

The prevalence of childhood obesity in this population was found to be low. However, children from urban schools and girls were proportionately more obese compared to their counterparts. Primary preventive measures for childhood obesity should start early in childhood and address socioeconomic factors of parents contributing to childhood obesity.

Nutrient intake in infancy and body mass index at six years in two population-based cohorts recruited before and after revision of infant dietary recommendations

BACKGROUND/AIMS

The dietary intake in infancy can affect growth and the risk of childhood overweight. The aim of this study was to compare the nutrient intake in infancy and the body mass index (BMI) at age 6 years in two population-based cohorts recruited before and after the revision of infant dietary recommendations.

METHODS

Two randomly selected population-based cohorts were recruited at birth and studied until 12 months of age and again at 6 years of age. Subjects were 90 and 170 children born in 1995-1996 and 2005, respectively. The dietary intake at 9 and 12 months was assessed via weighed food records. The height and weight from birth to age 12 months and at age 6 years were measured.

RESULTS

The contribution of protein to the total energy intake (E%) was significantly lower in the 2005 cohort than in the 1995-1996 cohort [11.9 vs. 14.4 E% (p < 0.001) at 9 months and 14.6 vs. 15.6 E% (p = 0.016) at 12 months]. Relatively fewer children were classified as being overweight (including obese) in the 2005 cohort, i.e. 12 versus 21% (p = 0.045).

CONCLUSION

The emphasis placed on the revised infant dietary recommendations resulted in a lower protein intake in the latter half of the first year. Changes in the infants' diets on the population level might have contributed to the lower overweight prevalence seen in the 2005 cohort.

Cesarean section and increased body mass index in school children: two cohort studies from distinct socioeconomic background areas in Brazil

Background

Recent studies have raised controversy regarding the association between cesarean section and later obesity in the offspring. The purpose of this study was to assess the association of cesarean section with increased body mass index (BMI) and obesity in school children from two Brazilian cities with distinct socioeconomic backgrounds.

Methods

Two birth cohorts respectively born in 1994 in Ribeirao Preto, a wealthy city in Southeast, and in 1997/98 in Sao Luis, a less wealthy city in Northeast of Brasil, were evaluated. After birth, 2,846 pairs of mothers-newborns were evaluated in Ribeirao Preto and 2,542 in Sao Luis. In 2004/05, 790 children aged 10/11 years were randomly reassessed in Ribeirao Preto and 673 at 7/9 years in Sao Luis. Information on type of delivery, maternal and child characteristics, socioeconomic position and anthropometric measurements were collected after birth and at school age. Obesity was defined as BMI ≥ 95th percentile at school age.

Results

Obesity rate was 13.0% in Ribeirao Preto and 2.1% in Sao Luis. Cesarean section was associated with obesity and remained significant after adjustment only in Ribeirao Preto [OR = 1.74 (95% CI: 1.04; 2.92)]. The association between cesarean section and BMI remained significant after adjustment for maternal schooling, maternal smoking during pregnancy, duration of breastfeeding, gender, birth weight and gestational age, type of school and, only in Sao Luis, pre-pregnancy maternal weight. In Ribeirao Preto children born by cesarean section had BMI 0.31 kg/m² (95%CI: 0.11; 0.51) higher than those born by vaginal delivery. In Sao Luis BMI of children born by cesarean section was 0.28 kg/m² higher (95%CI: 0.08; 0.49) than those born by vaginal delivery.

Conclusion

A positive association between cesarean section and increased BMI z-score was demonstrated in areas with different socioeconomic status in a middle-income country.

Mode of delivery and adiposity: Hong Kong's "Children of 1997" birth cohort

PURPOSE

To examine whether mode of delivery was associated with childhood adiposity in a developed non-Western context.

METHODS

We used generalized estimating equations to estimate the association of mode of delivery (vaginal or cesarean) with body mass index (BMI) z-score and overweight (including obesity) from 3 months to 13 years, in 7809 term birth (94% follow-up) from a population-representative Chinese birth cohort, "Children of 1997." We used multiple imputation for missing data.

RESULTS

The cesarean section rate (26%) was higher for children born in private hospitals, with lower gestational age, lower birth order, higher maternal age, higher maternal BMI, and higher family socioeconomic position. Cesarean section was not associated with BMI z-score from 3 months to 13 years (mean difference, 0.03; 95% confidence interval, -0.02 to 0.09) or overweight from 3 years to 13 years (odds ratio, 0.98; 95% confidence interval, 0.77 to 1.25) after adjusting for infant and maternal characteristics and family socioeconomic position.

CONCLUSIONS

In a non-Western developed setting, mode of delivery was not clearly associated with BMI or overweight (including obesity) into late childhood. From a public health perspective, the role of mode of delivery and its mechanistic pathway in the current burgeoning epidemic of obesity needs to be clarified.

Childhood obesity: a review of increased risk for physical and psychological comorbidities

BACKGROUND

Worldwide estimates of childhood overweight and obesity are as high as 43 million, and rates continue to increase each year. Researchers have taken interest in the childhood obesity epidemic and the impact of this condition across health domains. The consequences of childhood and adolescent obesity are extensive, including both medical and psychosocial comorbidities.

OBJECTIVE

The purpose of this review was to consolidate and highlight the recent literature on the comorbidities associated with childhood obesity, both nationally and internationally.

METHODS

PubMed and PsychINFO searches were conducted on childhood obesity and comorbidities.

RESULTS

The initial search of the terms obesity and comorbidity yielded >5000 published articles. Limits were set to include studies on children and adolescents that were published in peer-reviewed journals from 2002 to 2012. These limits narrowed the search to 938. Review of those articles resulted in 79 that are included in this review. The major medical comorbidities associated with childhood obesity in the current literature are metabolic risk factors, asthma, and dental health issues. Major psychological comorbidities include internalizing and externalizing disorders, attention-deficit hyperactivity disorder, and sleep problems.

CONCLUSIONS

The high prevalence rates of childhood obesity have resulted in extensive research in this area. Limitations to the current childhood obesity literature include differential definitions of weight status and cut-off levels for metabolic risk factors across studies. Additionally, some results are based on self-report of diagnoses rather than chart reviews or physician diagnosis. Even so, there is substantial support for metabolic risk factors, internalizing disorders, attention-deficit hyperactivity disorder, and decreased health-related quality of life as comorbidities to obesity in childhood. Additional investigations on other diseases and conditions that might be associated with childhood obesity are warranted and intervention research in this area is critical.

UK health visitors' role in identifying and intervening with infants at risk of developing obesity

Childhood obesity is associated with a number of modifiable risk factors that can be identified during infancy or earlier. In the UK, health visitors advise parents about infant feeding, but little is known about their role in obesity prevention. The aim of this study was to investigate the beliefs and current practices of UK health visitors in relation to recognising and intervening with infants at risk of developing obesity. Thirty members of the health visiting team were interviewed. The interviews were audio-recorded and transcribed verbatim. Thematic analysis was applied using an interpretative, inductive approach. Health visitors were aware of some of the modifiable risk factors for childhood obesity such as infant feeding practices. They felt they had a role in advising parents about diet but did not formally identify and/or intervene with larger infants. Infant overweight was considered a sensitive issue that was difficult to raise with parents. They believed some parents preferred larger infants and were unaware that their feeding practices might be contributing to obesity risk. A need for training and guidance was identified together with strategies to overcome system barriers. Health visitors do not currently target parents of infants at risk of obesity largely because they do not perceive they have appropriate guidance and skills to enable them to do so. There is an urgent need for tools and training to enable all health care professionals to recognise and manage infants at risk of developing obesity without creating a sense of blame.

The association between caesarean section and childhood obesity revisited: a cohort study

BACKGROUND

The mode of delivery has recently gained attention as another potential perinatal risk factor for childhood obesity but results are conflicting.

OBJECTIVE

To examine whether caesarean section is independently associated with childhood obesity after adjusting for a broad range of confounding factors.

METHODS

The current study used a population-based survey in Grade 5 students linked to a provincial perinatal registry in the Canadian province of Nova Scotia. Associations between caesarean section and childhood overweight and obesity at age 10/11 years were examined using multiple logistic regression.

RESULTS

Of the 4298 students who participated in the 2003 Children's Lifestyle and School Performance Study (response rate 51.1%), 3426 (80%) could be linked with information in the Atlee Perinatal Database, and 2988 mother-child pairs (70%) had complete information on the exposure and outcome. Compared to vaginal delivery, caesarean section was associated with offspring obesity (OR) 1.49, 95% CI 1.10 to 2.00) in the univariate analysis. After adding maternal prepregnancy weight to the multiple regression model, the OR for obesity dropped from 1.48 to 1.20 (95% CI 0.87 to 1.65). When caesarean section with and without labour were considered separately, we found no statistically significant associations relative to the vaginal delivery group (OR 1.24, 95% CI 0.84 to 1.82 and OR 1.03, 95% CI 0.58 to 1.84).

CONCLUSION

Our results do not support a causal association between caesarean section and childhood obesity. Maternal prepregnancy weight was an important confounder in the association between caesarean delivery and childhood obesity and needs to be considered in future studies.

Cesarean Section Is Associated with Increased Peripheral and Central Adiposity in Young Adulthood: Cohort Study

BACKGROUND

Cesarean section (CS) has been associated with obesity, measured by body mass index (BMI), in some studies. It has been hypothesized that this association, if causal, might be explained by changes in gut microbiota. However, little is known about whether CS is also associated with increased adiposity as measured by indicators other than BMI.

OBJECTIVE

To assess the association between CS and indicators of peripheral and central adiposity in young adults.

METHODS

The study was conducted on 2,063 young adults aged 23 to 25 years from the 1978/79Ribeirão Preto birth cohort, São Paulo, Brazil. CS was the independent variable. The anthropometric indicators of adiposity were: waist circumference (WC), waist-height ratio (WHtR), waist-hip ratio (WHR), tricipital skinfold (TSF), and subscapular skinfold (SSF). The association between CS and indicators of adiposity was investigated using a Poisson model, with robust adjustment of variance and calculation of incidence rate ratio (IRR) with 95% confidence interval (95%CI), and adjustment for birth variables.

RESULTS

Follow-up rate was 31.8%. The CS rate was 32%. Prevalences of increased WC, WHtR, WHR were 32.1%, 33.0% and 15.2%, respectively. After adjustment for birth variables, CS was associated with increased risk of adiposity when compared to vaginal delivery: 1.22 (95%CI 1.07; 1.39) for WC, 1.25 (95%CI 1.10;1.42) for WHtR, 1.45 (95%CI 1.18;1.79) for WHR, 1.36 (95%CI 1.04;1.78) for TSF, and 1.43 (95%CI 1.08;1.91) for SSF.

CONCLUSION

Subjects born by CS had a higher risk for increased peripheral and central adiposity during young adult age compared to those born by vaginal delivery. The association of CS with adiposity was consistently observed for all indicators and was robust after adjustment for a variety of early life confounders.

Gestational weight gain in accordance to the IOM/NRC criteria and the risk for childhood overweight: a meta-analysis

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Gestational weight gain is a modifiable risk factor for childhood overweight.

WHAT THIS STUDY ADDS

Exceeding the recommended gestational weight gain increases the risk for childhood overweight by about 30%. Interventions to avoid excessive weight gain are needed.

BACKGROUND

Overweight and obesity in children are thought to be related to prenatal priming. Gestational weight gain (GWG) might be a potential modifiable risk factor for childhood overweight.

OBJECTIVE

To quantify the associations of inadequate and excessive GWG with childhood overweight.

METHODS

The electronic literature search in six databases was complemented by a hand search for relevant articles. Papers were selected and quality was assessed. The effect estimates of the individual studies were pooled using a random-effects model.

RESULTS

The literature search yielded 1492 results in total, of which seven observational studies met the inclusion criteria. The studies had medium to good quality. The pooled estimate for the association between excessive GWG and childhood overweight yielded an odds ratio (OR) of 1.38 (95% confidence interval [CI]: 1.21-1.57). The association between inadequate GWG and childhood overweight yielded an OR of 0.91 (95% CI: 0.85-0.98).

CONCLUSION

These data provide evidence for at least a 21% risk for childhood overweight related to excessive GWG. Therefore, further efforts to design appropriate interventions against excessive GWG may appear warranted.

Validity of self-reported weight and stature in adolescents from Cuiabá, Central-Western Brazil

OBJECTIVE: This study assessed the agreement between self-reported and measured weight and stature in adolescents. METHODS: Ninety-seven students from public and private high schools of Cuiabá, in the state of Mato Grosso, Brazil (14 to 19 years old), were examined to assess the validity of self-reported weight and stature. The adolescents reported their weight and stature, which were subsequently measured by standard procedures. The body mass index was calculated from both self-reported and measured data. Weight status was classified according to body mass index Z-score and World Health Organization criteria. The differences between the self-reported and measured means were tested by the Student's paired t-test. Weighted Kappa's coefficient of agreement was used to assess the variations in weight status categorization using informed and measured data. Agreement between measurements was assessed by the Bland-Altman method and intraclass correlation coefficient. RESULTS: The means of self-reported and measured weights (p=0.30), statures (p=0.76) and body mass index (p=0.47) were not significantly different. There was high agreement between self-reported and measured measurements according to intraclass correlation coefficient (weight: r=0.99; stature: r=0.96; body mass index: r=0.97) and the mean agreements estimated by the Bland-Altman method were 99% for weight and 100% for stature. CONCLUSION: Given the excellent agreement with measured data, self-reported weight and stature are considered valid to be used in epidemiological studies on adolescents of Cuiabá, Mato Grosso, Brazil.

The Impact of Cigarette Quitting during Pregnancy on Other Prenatal Health Behaviors

Several economic studies have evaluated the effects of cigarette smoking and quitting on other health behaviors such as alcohol use and weight gain. However, there is little research that evaluates the effects of cigarette quitting during pregnancy on other health behaviors such as caloric intake, alcohol consumption, multivitamin use, and caffeine intake. In this paper, we evaluate these effects and employ a genetic variant that predicts cigarette quitting to aid in identification. We find some evidence that cigarette quitting during pregnancy may increase multivitamin use and caloric intake and reduce caffeine consumption.

Early predictors of obesity and cardiovascular risk among American Indian children

American Indian (AI) children have the highest rates of obesity among ethnic groups in the United States, and rates continue to increase. This study was designed to examine the effects of prenatal and early postnatal factors on AI children's body mass index (BMI) trajectories, adiposity, and cardiovascular risk markers during early childhood. We screened 471 AI children (ages 5-8) from three Wisconsin tribes. Screenings included anthropometric and body fat measures and non-fasting lipid and glucose via fingerstick blood samples. Tribal records from Women Infants and Children (WIC) programs and clinic charts provided data on children's BMI trajectories, maternal prenatal factors, and the early postnatal feeding environment. Forty-seven percent of children were overweight or obese. Analysis of growth trajectories showed that children's BMI category was largely determined within the 1 year of life. Significant predictors of children's BMI category at age 1 included macrosomia (OR 4.38), excess gestational weight gain (OR 1.64) and early termination of breastfeeding (OR 1.66). Children who were overweight/obese at age 1 had greater odds of being overweight (OR 3.42) or obese (OR 3.36), and having unhealthy levels of body fat (OR 2.95) and LDL cholesterol (OR 1.64) at ages 5-8. Children's BMI category is determined in the early post-natal environment, within the 1 year of life, by factors including excess gestational weight gain and early termination of breastfeeding. In turn, children's BMI category at age 1 predicts the emergence of cardiovascular risk markers in early childhood.

Evaluation of the association between maternal smoking, childhood obesity, and metabolic disorders: a national toxicology program workshop review

BACKGROUND

An emerging literature suggests that environmental chemicals may play a role in the development of childhood obesity and metabolic disorders, especially when exposure occurs early in life.

OBJECTIVE

Here we assess the association between these health outcomes and exposure to maternal smoking during pregnancy as part of a broader effort to develop a research agenda to better understand the role of environmental chemicals as potential risk factors for obesity and metabolic disorders.

METHODS

PubMed was searched up to 8 March 2012 for epidemiological and experimental animal studies related to maternal smoking or nicotine exposure during pregnancy and childhood obesity or metabolic disorders at any age. A total of 101 studies-83 in humans and 18 in animals-were identified as the primary literature.

DISCUSSION

Current epidemiological data support a positive association between maternal smoking and increased risk of obesity or overweight in offspring. The data strongly suggest a causal relation, although the possibility that the association is attributable to unmeasured residual confounding cannot be completely ruled out. This conclusion is supported by findings from laboratory animals exposed to nicotine during development. The existing literature on human exposures does not support an association between maternal smoking during pregnancy and type 1 diabetes in offspring. Too few human studies have assessed outcomes related to type 2 diabetes or metabolic syndrome to reach conclusions based on patterns of findings. There may be a number of mechanistic pathways important for the development of aberrant metabolic outcomes following perinatal exposure to cigarette smoke, which remain largely unexplored.

CONCLUSIONS

From a toxicological perspective, the linkages between maternal smoking during pregnancy and childhood overweight/obesity provide proof-of-concept of how early-life exposure to an environmental toxicant can be a risk factor for childhood obesity.

Improving breastfeeding rates in an "at risk" population

A new public health frontier challenging maternity care is addressing the sub-optimal breastfeeding rates of women who are obese. Despite the World Health Organisation's recommendation that breastfeeding is initiated within the first hour of birth and continued exclusively for six months, less than half of infants and young children globally are optimally breastfed. While initiation rates of exclusive breastfeeding immediately after birth are as high as 90 percent in Australia, this rate dramatically declines in the first few weeks postpartum, with only approximately 15 percent of infants exclusively breastfed to five months of age (less than 6 months). The aim of this paper was to highlight difficulties obese women have breastfeeding and highlight implications for research and practice.

The impact of cesarean section on offspring overweight and obesity: a systematic review and meta-analysis

Studies have reported inconsistent results concerning the association of cesarean section with offspring obesity. We performed a systematic review and meta-analysis to examine whether cesarean section increases the risk of later overweight and obesity. Pubmed, Embase and Web of Science were searched using different combinations of two groups of keywords: 'cesarean' and 'overweight/obesity'. Cohort or case-control studies that reported the association of cesarean section with childhood (3-8 years), adolescence (9-18 years) and/or adult (>19 years) overweight/obesity were eligible. Where possible, adjusted risk estimates were pooled using a random effects model; otherwise unadjusted estimates were pooled. Statistical heterogeneity was assessed with I(2) statistics; the values of 25%, 50% and 75% were considered to indicate low, medium and high heterogeneity, respectively. We conducted a subgroup analysis to identify the sources of heterogeneity according to study quality defined on the basis of the Newcastle-Ottawa Scale. In total, two case-control and seven cohort studies were identified for the literature review and 15 separate risk estimates were included in the meta-analysis. The overall pooled odds ratio (OR) of overweight/obesity for offspring delivered by cesarean section compared with those born vaginally was 1.33 (95% confidence interval (CI) 1.19, 1.48; I(2)=63%); the OR was 1.32 (1.15, 1.51) for children, 1.24 (1.00, 1.54) for adolescents and 1.50 (1.02, 2.20) for adults. In subgroup analysis, the overall pooled OR was 1.18 (1.09, 1.27; I(2)=29%) for high-quality studies and 1.78 (1.43, 2.22; I(2)=24%) for medium-quality (P for interaction=0.0005); no low-quality studies were identified. The ORs for children, adolescents and adults all tended to be lower for high-quality studies compared with medium-quality studies. Our results indicated that cesarean section was moderately associated with offspring overweight and obesity. This finding has public health implications, given the increase in cesarean births in many countries.

Systematic review and meta-analyses of risk factors for childhood overweight identifiable during infancy

OBJECTIVE

To determine risk factors for childhood overweight that can be identified during the first year of life to facilitate early identification and targeted intervention.

DESIGN

Systematic review and meta-analysis.

SEARCH STRATEGY

Electronic database search of MEDLINE, EMBASE, PubMed and CAB Abstracts.

ELIGIBILITY CRITERIA

Prospective observational studies following up children from birth for at least 2 years.

RESULTS

Thirty prospective studies were identified. Significant and strong independent associations with childhood overweight were identified for maternal pre-pregnancy overweight, high infant birth weight and rapid weight gain during the first year of life. Meta-analysis comparing breastfed with non-breastfed infants found a 15% decrease (95% CI 0.74 to 0.99; I(2)=73.3%; n=10) in the odds of childhood overweight. For children of mothers smoking during pregnancy there was a 47% increase (95% CI 1.26 to 1.73; I(2)=47.5%; n=7) in the odds of childhood overweight. There was some evidence associating early introduction of solid foods and childhood overweight. There was conflicting evidence for duration of breastfeeding, socioeconomic status at birth, parity and maternal marital status at birth. No association with childhood overweight was found for maternal age or education at birth, maternal depression or infant ethnicity. There was inconclusive evidence for delivery type, gestational weight gain, maternal postpartum weight loss and 'fussy' infant temperament due to the limited number of studies.

CONCLUSIONS

Several risk factors for both overweight and obesity in childhood are identifiable during infancy. Future research needs to focus on whether it is clinically feasible for healthcare professionals to identify infants at greatest risk.

Role of environmental chemicals in diabetes and obesity: a National Toxicology Program workshop review

BACKGROUND

There has been increasing interest in the concept that exposures to environmental chemicals may be contributing factors to the epidemics of diabetes and obesity. On 11-13 January 2011, the National Institute of Environmental Health Sciences (NIEHS) Division of the National Toxicology Program (NTP) organized a workshop to evaluate the current state of the science on these topics of increasing public health concern.

OBJECTIVE

The main objective of the workshop was to develop recommendations for a research agenda after completing a critical analysis of the literature for humans and experimental animals exposed to certain environmental chemicals. The environmental exposures considered at the workshop were arsenic, persistent organic pollutants, maternal smoking/nicotine, organotins, phthalates, bisphenol A, and pesticides. High-throughput screening data from Toxicology in the 21st Century (Tox21) were also considered as a way to evaluate potential cellular pathways and generate -hypotheses for testing which and how certain chemicals might perturb biological processes related to diabetes and obesity.

CONCLUSIONS

Overall, the review of the existing literature identified linkages between several of the environmental exposures and type 2 diabetes. There was also support for the "developmental obesogen" hypothesis, which suggests that chemical exposures may increase the risk of obesity by altering the differentiation of adipocytes or the development of neural circuits that regulate feeding behavior. The effects may be most apparent when the developmental exposure is combined with consumption of a high-calorie, high-carbohydrate, or high-fat diet later in life. Research on environmental chemical exposures and type 1 diabetes was very limited. This lack of research was considered a critical data gap. In this workshop review, we outline the major themes that emerged from the workshop and discuss activities that NIEHS/NTP is undertaking to address research recommendations. This review also serves as an introduction to an upcoming series of articles that review the literature regarding specific exposures and outcomes in more detail.

Associations of maternal prepregnancy body mass index and gestational weight gain with adult offspring cardiometabolic risk factors: the Jerusalem Perinatal Family Follow-up Study

BACKGROUND

Accumulating evidence demonstrates that both maternal prepregnancy body mass index (mppBMI) and gestational weight gain (GWG) are associated with adult offspring adiposity. However, whether these maternal attributes are related to other cardiometabolic risk factors in adulthood has not been comprehensively studied.

METHODS AND RESULTS

We used a birth cohort of 1400 young adults born in Jerusalem who had extensive archival data and clinical information at 32 years of age to prospectively examine the associations of mppBMI and GWG with adiposity and related cardiometabolic outcomes. Greater mppBMI, independently of GWG and confounders, was significantly associated with higher offspring BMI, waist circumference, systolic and diastolic blood pressures, insulin, and triglycerides and with lower high-density lipoprotein cholesterol. For example, the effect sizes were translated to nearly 5 kg/m(2) higher mean BMI, 8.4 cm higher waist circumference, 0.13 mmol/L (11.4 mg/dL) higher triglycerides, and 0.10 mmol/L (3.8 mg/dL) lower high-density lipoprotein cholesterol among offspring of mothers within the upper mppBMI quartile (mppBMI >26.4 kg/m(2)) compared with the lower quartile (mppBMI <21.0 kg/m(2)). GWG, independently of mppBMI, was positively associated with offspring adiposity; differences of 1.6 kg/m(2) in BMI and 2.4 cm in waist were observed when offspring of mothers in the upper (GWG >14 kg) and lower (GWG <9 kg) quartiles of GWG were compared. Further adjustment for offspring adiposity attenuated the observed associations to the null.

CONCLUSIONS

Maternal size both before and during pregnancy is associated with cardiometabolic risk factors in young adult offspring. The associations appear to be driven mainly by offspring adiposity. Future studies that explore mechanisms underlying the intergenerational cycle of obesity are warranted to identify potentially novel targets for cardiometabolic risk-reduction interventions.

Intergenerational cycle of obesity and diabetes: how can we reduce the burdens of these conditions on the health of future generations?

Prepregnancy overweight or obesity and excessive gestational weight gain have been associated with increased risk of maternal and neonatal complications. Moreover, offspring from obese women are more likely to develop obesity, diabetes mellitus, and cardiovascular diseases in their lifetime. Gestational diabetes mellitus (GDM) is one of the most common complications associated with obesity and appears to have a direct impact on the future metabolic health of the child. Fetal programming of metabolic function induced by obesity and GDM may have intergenerational effect and thus perpetuate the epidemic of cardiometabolic conditions. The present paper thus aims at discussing the impact of maternal obesity and GDM on the developmental programming of obesity and metabolic disorders in the offspring. The main interventions designed to reduce maternal obesity and GDM and their ability to break the vicious circle that perpetuates the transmission of obesity and metabolic conditions to the next generations are also addressed.

Limiting weight gain in overweight and obese women during pregnancy to improve health outcomes: the LIMIT randomised controlled trial

Background

Obesity is a significant global health problem, with the proportion of women entering pregnancy with a body mass index greater than or equal to 25 kg/m² approaching 50%. Obesity during pregnancy is associated with a well-recognised increased risk of adverse health outcomes both for the woman and her infant, however there is more limited information available regarding effective interventions to improve health outcomes.

The aims of this randomised controlled trial are to assess whether the implementation of a package of dietary and lifestyle advice to overweight and obese women during pregnancy to limit gestational weight gain is effective in improving maternal, fetal and infant health outcomes.

Methods/Design

Design: Multicentred randomised, controlled trial.

Inclusion Criteria: Women with a singleton, live gestation between 10⁺⁰-20⁺⁰ weeks who are obese or overweight (defined as body mass index greater than or equal to 25 kg/m²), at the first antenatal visit.

Trial Entry & Randomisation: Eligible, consenting women will be randomised between 10⁺⁰ and 20⁺⁰ weeks gestation using a central telephone randomisation service, and randomisation schedule prepared by non-clinical research staff with balanced variable blocks. Stratification will be according to maternal BMI at trial entry, parity, and centre where planned to give birth.

Treatment Schedules: Women randomised to the Dietary and Lifestyle Advice Group will receive a series of inputs from research assistants and research dietician to limit gestational weight gain, and will include a combination of dietary, exercise and behavioural strategies.

Women randomised to the Standard Care Group will continue to receive their pregnancy care according to local hospital guidelines, which does not currently include routine provision of dietary, lifestyle and behavioural advice.

Outcome assessors will be blinded to the allocated treatment group.

Primary Study Outcome: infant large for gestational age (defined as infant birth weight ≥ 90^th centile for gestational age).

Sample Size: 2,180 women to detect a 30% reduction in large for gestational age infants from 14.40% (p = 0.05, 80% power, two-tailed).

Discussion

This is a protocol for a randomised trial. The findings will contribute to the development of evidence based clinical practice guidelines.

Trial Registration

Australian and New Zealand Clinical Trials Registry ACTRN12607000161426