Early life risk factors for obesity in childhood: cohort study
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《英国医生杂志》
1 University of Glasgow Division of Developmental Medicine, Yorkhill Hospitals, Glasgow G3 8SJ, 2 Unit of Paediatric and Perinatal Epidemiology, Institute of Child Health, University of Bristol, 3 School of Public Health, Tehran University of Medical Sciences, Islamic Republic of Iran
Correspondence to: J J Reilly jjr2y@clinmed.gla.ac.uk
Objective To identify risk factors in early life (up to 3 years of age) for obesity in children in the United Kingdom.
Design Prospective cohort study.
Setting Avon longitudinal study of parents and children, United Kingdom.
Participants 8234 children in cohort aged 7 years and a subsample of 909 children (children in focus) with data on additional early growth related risk factors for obesity.
Main outcome measures Obesity at age 7 years, defined as a body mass index 3 95th centile relative to reference data for the UK population in 1990.
Results Eight of 25 putative risk factors were associated with a risk of obesity in the final models: parental obesity (both parents: adjusted odds ratio, 10.44, 95% confidence interval 5.11 to 21.32), very early (by 43 months) body mass index or adiposity rebound (15.00, 5.32 to 42.30), more than eight hours spent watching television per week at age 3 years (1.55, 1.13 to 2.12), catch-up growth (2.60, 1.09 to 6.16), standard deviation score for weight at age 8 months (3.13, 1.43 to 6.85) and 18 months (2.65, 1.25 to 5.59); weight gain in first year (1.06, 1.02 to 1.10 per 100 g increase); birth weight, per 100 g (1.05, 1.03 to 1.07); and short (< 10.5 hours) sleep duration at age 3 years (1.45, 1.10 to 1.89).
Conclusion Eight factors in early life are associated with an increased risk of obesity in childhood.
An epidemic of childhood obesity has occurred in recent years, beginning in the late 1980s in the United Kingdom.1 It is of concern because of adverse consequences in the short term and long term.1 2 The identification of risk factors is the key to prevention.3 Evidence on risk factors for childhood obesity is limited at present,4 5 although awareness is increasing for the importance of the environment in early life. Almost all recognised risk factors are potential rather than confirmed. A systematic review found that most previous studies on risk factors for obesity were unable to adequately account for confounding variables (particularly socioeconomic status),5 were mainly cross sectional, were underpowered,4 5 and failed to investigate the effect of several potential risk factors simultaneously.4 5
We identified and quantified risk factors for obesity at age 7 years in children who were participating in the Avon longitudinal study of parents and children (ALSPAC). The study concerns a large contemporary cohort in which confounding variables are being considered and potential risk factors are being tested simultaneously. For the present study, we took into account only risk factors supported by a priori hypotheses.
Methods
The Avon longitudinal study of parents and children is a longitudinal birth cohort study of the determinants of development, health, and disease during childhood and beyond. This study is described in detail elsewhere.6 Briefly, 14 541 pregnant women with an expected date of delivery between April 1991 and December 1992 were enrolled; 13 971 of their children formed the original cohort. About 85-90% of eligible mothers took part in the study. Parents gave informed written consent for their children to participate. Data have been collected from questionnaires completed by the parents, medical records, and biological samples. We randomly selected a subsample of children from the last six months of recruitment (children in focus group), aged from 4 months to 5 years, and invited their parents to bring them in for regular physical examinations. From age 7 years onwards these examinations were extended to the whole cohort.
Anthropometric variables
We measured height to 0.1 cm using the Harpenden stadiometer (Holtain; Crymych, Wales). Weight was measured to 0.1 kg. From these values we calculated the body mass index (weight (kg)/(height (m)2). Body mass indices were converted to standard deviation scores relative to UK reference data in 1990.7
Definition of obesity
We defined obesity as a body mass index equal to or greater than the 95th centile, equivalent to a standard deviation score of 1.64 or more. This definition has high specificity and moderate sensitivity for identifying the children with highest body fat percentage within the British population.8 9 Obesity defined in this way is also biologically meaningful as it identifies those children who are most likely to experience comorbidity, such as persistence of obesity, presence and clustering of cardiovascular risk factors, and psychological problems.2
Potential risk factors
We chose putative risk factors on the basis of previously reported associations with obesity, or plausible prior hypotheses. We cross checked the results of our literature search against a systematic review.5 Overall, we identified 31 potential risk factors. Measures for 21 of these risk factors were available for the entire cohort of the Avon longitudinal study of parents and children. A further four potential risk factors relating to growth in infancy and early childhood were available for the children in focus subsample (table 1).
Table 1 Potential risk factors and confounders, method and time of data collection, and factor level of analysis
Statistical analyses
We carried out a multivariable analysis for the prevalence of obesity in three stages using multivariable binary logistic regression models. Firstly, owing to the strong association between maternal education (as a proxy for socioeconomic status) and childhood obesity, we assessed whether the effect of potential risk factors was confounded by the mother's education. Secondly, in an effort to reduce colinearity and to minimise the likelihood of producing misleading estimates for the variables (data not shown), we analysed putative risk factors for childhood obesity (the effects of which were found to be independent of maternal education) simultaneously within each of the four risk factor groups (intrauterine and perinatal factors; infant feeding and complementary feeding (weaning) practice; family characteristics and demography; and lifestyle in early childhood). Finally, risk factors that were independently significant (P < 0.10) at the within group stage were then entered into a final model in which we analysed all variables simultaneously. In the final model we further adjusted the variables for sex (we had a priori reasons for believing that sex might mediate some of the effects of some risk factors, although in practice its inclusion or exclusion made little difference to the odds ratios in the final model); maternal education (to control or adjust for socioeconomic status); and, for the food group variables,10 the child's estimated energy intake at age 3 years. We used 2 tests for linear trend for ordered categorical variables and Fisher's exact test in contingency tables when the expected frequency in any cell was less than 5.
To assess the effect of the four growth related risk factors (measured in the children in focus subsample only) on obesity, we used multivariable binary logistic regression models, while controlling for all other statistically significant risk factors obtained from the analysis of the whole cohort. Owing to the correlation between these growth related risk factors, we independently assessed their effect on obesity. We produced five separate models for the four risk factors. One risk factor, size in early life, was measured at age 8 and 18 months.
Results
In total, 8234 children attended the clinic at age 7. Measures for height and weight were available for 7758 children (3934 boys and 3824 girls; 55.5% of the original 13 971 children) median age 7.6 years (range 6.9-8.5 years). The prevalence of obesity did not differ significantly between the sexes (9.2% for boys (n = 362) and 8.1% for girls (n = 309; P = 0.08)). Overall, 5493 children (70.8% of those with measures for height and weight who attended at age 7, 39.3% of the original cohort) had complete data for the multivariable analyses.
Risk factors in entire cohort
Intrauterine and perinatal factors
Increasing birth weight was independently and linearly associated with increasing prevalence of obesity at age 7 (table 2). Obesity at age 7 was also significantly associated with maternal smoking between 28 and 32 weeks' gestation, with some indication of a dose response (2 test for linear trend 27.17).
Table 2 Associations between 21 risk factors and obesity at age 7 years in cohort of Avon longitudinal study of parents and children. Values are percentages (numbers) unless stated otherwise
Infant feeding and weaning practice
The apparent protective effect of exclusive breastfeeding on obesity at age 7 observed in the univariable analysis remained when breastfeeding was considered together with the other infant feeding and weaning practice variable (adjusted odds ratio 0.70, 95% confidence interval 0.54 to 0.91), but had disappeared in the final model (table 2). In the final model, timing of introduction of complementary feeding was not significantly related to the risk of obesity at age 7.
Family characteristics and demographics
When only one parent was obese, the risk of obesity at age 7 was increased. The risk was higher when both parents were obese (adjusted odds ratio 10.44, 5.11 to 21.32; table 2).
Lifestyle in early childhood
Sleep Sleep duration in children aged 30 months was independently associated with prevalence of obesity at age 7 (table 2). Children in the lowest two quarters of sleep duration (< 10.5 hours and 10.5-10.9 hours) were more likely to be obese at age 7 than children in the highest quarter (> 12 hours; 2 test for linear trend 17.8).
Sedentary behaviour The odds ratio for obesity increased linearly as the number of hours of television viewing increased (2 test for linear trend 26.7). For children reported to watch television for 4-8 hours per week at age 3 the adjusted odds ratio for obesity at age 7 was 1.37 (1.02 to 1.83). For those reported to watch more than eight hours per week the adjusted odds ratio was 1.55 (1.13 to 2.12).
Dietary patterns We found no conclusive evidence of an association between dietary patterns at age 3 and risk of obesity at age 7. A junk food type dietary pattern at age 3 was significantly associated with risk of obesity at age 7, although the association only just reached significance at the 10% level in the final model (table 2).
Risk factors in children in focus subsample
The prevalence of obesity at 7 years in the children in focus subsample was not significantly different from that in the entire cohort (8.7%; 79/909). Children in the highest quarter for weight (standard deviation scores) at age 8 months and 18 months were more likely to be obese at age 7 than children in the lower quarters (table 3). Early adiposity or body mass index rebound, catch-up growth between birth and two years, and high rates of weight gain in the first 12 months were also independently associated with obesity at age 7 (table 3).
Table 3 Associations between four risk factors and obesity at age 7 years in children in focus subsample. Values are numbers (percentages) unless stated otherwise
Discussion
Reilly JJ, Dorosty AR. Epidemic of obesity in UK children. Lancet 1999;354: 1874-5.
Reilly JJ, Methven E, McDowell ZC, Hacking B, Alexander D, Stewart L, et al. Health consequences of obesity. Arch Dis Child 2003;88: 748-52.
Dietz WH. Birth weight, socioeconomic class, and adult adiposity among African Americans. Am J Clin Nutr 2000;72: 335-6.
Dietz WH. Breastfeeding may help prevent childhood overweight. JAMA 2001;285: 2506-7.
Parsons TJ, Power C, Summerbell CD. Childhood predictors of adult obesity: systematic review. Int J Obes 1999;23 (suppl 8): S1-107.
Golding J, Pembrey M, Jones R, ALSPAC Study Team. ALSPAC-the Avon longitudinal study of parents and children I: study methodology. Paediatr Perinat Epidemiol 2001;15: 74-87.
Cole TJ, Freeman JV, Preece MA. Body mass index reference curves for the UK, 1990. Arch Dis Child 1995;73: 25-9.
Reilly J, Dorosty AR, Emmett PM, ALSPAC Study Team. Identification of the obese child: adequacy of the BMI for clinical practice and epidemiology. Int J Obes 2000;24: 1623-7.
Reilly JJ, Wilson ML, Summerbell CD, Wilson AC. Obesity: diagnosis, prevention, and treatment; evidence based answers to common questions. Arch Dis Child 2002;86: 392-4.
North K, Emmett P, ALSPAC Study Team. Multivariate analysis of diet among three-year-old children and associations with socio-demographic characteristics. Eur J Clin Nutr 2001;54: 73-80.
Whitaker RC. Obesity prevention in primary care: four behaviors to target. Arch Pediatr Adolesc Med 2003;157: 725-7.
Armstrong J, Reilly JJ. Child Health Information Team. Breastfeeding and lowering the risk of childhood obesity. Lancet 2002;359: 2003-4.
Bogen DL, Hanusa BH, Whitaker RC. The effect of breastfeeding with and without concurrent formula feeding on risk of obesity at 4 years of age. Obes Res 2004;12: 1527-35.
Von Kries R, Toschke AM, Koletzko B, Slikker W Jr. Maternal smoking during pregnancy and childhood obesity. Am J Epidemiol 2002;156: 954-61.
Grove KL, Sekhon HS, Brogan RS, Keller JA, Smith MS, Spindel ER. Chronic maternal nicotine exposure alters neuronal systems in the arcuate nucleus that regulate feeding behavior in the newborn rhesus macaque. J Clin Endocrinol Metab 2001;86: 5420-6.
Dorosty AR, Emmett PM, Reilly JJ, ALSPAC Study Team. Factors associated with early adiposity rebound. Pediatrics 2000;105: 1115-8.
Francis LA, Lee Y, Birch LL. Parental weight status and girls television viewing, snacking, and body mass indexes. Obes Res 2003;11: 143-51.
Gortmaker SL, Must A, Sobol AM, Petgerson K, Colditz GA, Dietz WH. Television viewing as a cause of increasing obesity among children in the United States 1986-1990. Arch Pediatr Adolesc Med 1996;150: 356-62.
Robinson TN. Reducing children's television viewing to prevent obesity: randomized controlled trial. JAMA 1999;282: 1561-7.
Stettler N, Zemel BS, Kumanyika S, Stallings VA. Infant weight gain and childhood overweight status in a multicenter cohort study. Pediatrics 2002;109: 194-9.
Ong KK, Ahmed ML, Emmett PM, Preece MA, Dunger DB. Association between postnatal catch-up growth and obesity in childhood: prospective cohort study. BMJ 2000;320: 967-71.
Birch LL, Fisher JO. Development of eating behaviors among children and adolescents. Pediatrics 1998;101: 539-49.
Dabelea D, Hanson RL, Lindsay RS, Pettitt DJ, Imperatore G, Gabir MM, et al. Intrauterine exposure to diabetes conveys risks for type 2 diabetes and obesity: a study of discordant sibships. Diabetes 2000;49: 2208-11.
Dietz WH. Periods of risk in childhood for the development of adult obesity—what do we need to learn? J Nutr 1997;127(suppl 4): S1884-6.(John J Reilly, reader in paediatric ener)
Correspondence to: J J Reilly jjr2y@clinmed.gla.ac.uk
Objective To identify risk factors in early life (up to 3 years of age) for obesity in children in the United Kingdom.
Design Prospective cohort study.
Setting Avon longitudinal study of parents and children, United Kingdom.
Participants 8234 children in cohort aged 7 years and a subsample of 909 children (children in focus) with data on additional early growth related risk factors for obesity.
Main outcome measures Obesity at age 7 years, defined as a body mass index 3 95th centile relative to reference data for the UK population in 1990.
Results Eight of 25 putative risk factors were associated with a risk of obesity in the final models: parental obesity (both parents: adjusted odds ratio, 10.44, 95% confidence interval 5.11 to 21.32), very early (by 43 months) body mass index or adiposity rebound (15.00, 5.32 to 42.30), more than eight hours spent watching television per week at age 3 years (1.55, 1.13 to 2.12), catch-up growth (2.60, 1.09 to 6.16), standard deviation score for weight at age 8 months (3.13, 1.43 to 6.85) and 18 months (2.65, 1.25 to 5.59); weight gain in first year (1.06, 1.02 to 1.10 per 100 g increase); birth weight, per 100 g (1.05, 1.03 to 1.07); and short (< 10.5 hours) sleep duration at age 3 years (1.45, 1.10 to 1.89).
Conclusion Eight factors in early life are associated with an increased risk of obesity in childhood.
An epidemic of childhood obesity has occurred in recent years, beginning in the late 1980s in the United Kingdom.1 It is of concern because of adverse consequences in the short term and long term.1 2 The identification of risk factors is the key to prevention.3 Evidence on risk factors for childhood obesity is limited at present,4 5 although awareness is increasing for the importance of the environment in early life. Almost all recognised risk factors are potential rather than confirmed. A systematic review found that most previous studies on risk factors for obesity were unable to adequately account for confounding variables (particularly socioeconomic status),5 were mainly cross sectional, were underpowered,4 5 and failed to investigate the effect of several potential risk factors simultaneously.4 5
We identified and quantified risk factors for obesity at age 7 years in children who were participating in the Avon longitudinal study of parents and children (ALSPAC). The study concerns a large contemporary cohort in which confounding variables are being considered and potential risk factors are being tested simultaneously. For the present study, we took into account only risk factors supported by a priori hypotheses.
Methods
The Avon longitudinal study of parents and children is a longitudinal birth cohort study of the determinants of development, health, and disease during childhood and beyond. This study is described in detail elsewhere.6 Briefly, 14 541 pregnant women with an expected date of delivery between April 1991 and December 1992 were enrolled; 13 971 of their children formed the original cohort. About 85-90% of eligible mothers took part in the study. Parents gave informed written consent for their children to participate. Data have been collected from questionnaires completed by the parents, medical records, and biological samples. We randomly selected a subsample of children from the last six months of recruitment (children in focus group), aged from 4 months to 5 years, and invited their parents to bring them in for regular physical examinations. From age 7 years onwards these examinations were extended to the whole cohort.
Anthropometric variables
We measured height to 0.1 cm using the Harpenden stadiometer (Holtain; Crymych, Wales). Weight was measured to 0.1 kg. From these values we calculated the body mass index (weight (kg)/(height (m)2). Body mass indices were converted to standard deviation scores relative to UK reference data in 1990.7
Definition of obesity
We defined obesity as a body mass index equal to or greater than the 95th centile, equivalent to a standard deviation score of 1.64 or more. This definition has high specificity and moderate sensitivity for identifying the children with highest body fat percentage within the British population.8 9 Obesity defined in this way is also biologically meaningful as it identifies those children who are most likely to experience comorbidity, such as persistence of obesity, presence and clustering of cardiovascular risk factors, and psychological problems.2
Potential risk factors
We chose putative risk factors on the basis of previously reported associations with obesity, or plausible prior hypotheses. We cross checked the results of our literature search against a systematic review.5 Overall, we identified 31 potential risk factors. Measures for 21 of these risk factors were available for the entire cohort of the Avon longitudinal study of parents and children. A further four potential risk factors relating to growth in infancy and early childhood were available for the children in focus subsample (table 1).
Table 1 Potential risk factors and confounders, method and time of data collection, and factor level of analysis
Statistical analyses
We carried out a multivariable analysis for the prevalence of obesity in three stages using multivariable binary logistic regression models. Firstly, owing to the strong association between maternal education (as a proxy for socioeconomic status) and childhood obesity, we assessed whether the effect of potential risk factors was confounded by the mother's education. Secondly, in an effort to reduce colinearity and to minimise the likelihood of producing misleading estimates for the variables (data not shown), we analysed putative risk factors for childhood obesity (the effects of which were found to be independent of maternal education) simultaneously within each of the four risk factor groups (intrauterine and perinatal factors; infant feeding and complementary feeding (weaning) practice; family characteristics and demography; and lifestyle in early childhood). Finally, risk factors that were independently significant (P < 0.10) at the within group stage were then entered into a final model in which we analysed all variables simultaneously. In the final model we further adjusted the variables for sex (we had a priori reasons for believing that sex might mediate some of the effects of some risk factors, although in practice its inclusion or exclusion made little difference to the odds ratios in the final model); maternal education (to control or adjust for socioeconomic status); and, for the food group variables,10 the child's estimated energy intake at age 3 years. We used 2 tests for linear trend for ordered categorical variables and Fisher's exact test in contingency tables when the expected frequency in any cell was less than 5.
To assess the effect of the four growth related risk factors (measured in the children in focus subsample only) on obesity, we used multivariable binary logistic regression models, while controlling for all other statistically significant risk factors obtained from the analysis of the whole cohort. Owing to the correlation between these growth related risk factors, we independently assessed their effect on obesity. We produced five separate models for the four risk factors. One risk factor, size in early life, was measured at age 8 and 18 months.
Results
In total, 8234 children attended the clinic at age 7. Measures for height and weight were available for 7758 children (3934 boys and 3824 girls; 55.5% of the original 13 971 children) median age 7.6 years (range 6.9-8.5 years). The prevalence of obesity did not differ significantly between the sexes (9.2% for boys (n = 362) and 8.1% for girls (n = 309; P = 0.08)). Overall, 5493 children (70.8% of those with measures for height and weight who attended at age 7, 39.3% of the original cohort) had complete data for the multivariable analyses.
Risk factors in entire cohort
Intrauterine and perinatal factors
Increasing birth weight was independently and linearly associated with increasing prevalence of obesity at age 7 (table 2). Obesity at age 7 was also significantly associated with maternal smoking between 28 and 32 weeks' gestation, with some indication of a dose response (2 test for linear trend 27.17).
Table 2 Associations between 21 risk factors and obesity at age 7 years in cohort of Avon longitudinal study of parents and children. Values are percentages (numbers) unless stated otherwise
Infant feeding and weaning practice
The apparent protective effect of exclusive breastfeeding on obesity at age 7 observed in the univariable analysis remained when breastfeeding was considered together with the other infant feeding and weaning practice variable (adjusted odds ratio 0.70, 95% confidence interval 0.54 to 0.91), but had disappeared in the final model (table 2). In the final model, timing of introduction of complementary feeding was not significantly related to the risk of obesity at age 7.
Family characteristics and demographics
When only one parent was obese, the risk of obesity at age 7 was increased. The risk was higher when both parents were obese (adjusted odds ratio 10.44, 5.11 to 21.32; table 2).
Lifestyle in early childhood
Sleep Sleep duration in children aged 30 months was independently associated with prevalence of obesity at age 7 (table 2). Children in the lowest two quarters of sleep duration (< 10.5 hours and 10.5-10.9 hours) were more likely to be obese at age 7 than children in the highest quarter (> 12 hours; 2 test for linear trend 17.8).
Sedentary behaviour The odds ratio for obesity increased linearly as the number of hours of television viewing increased (2 test for linear trend 26.7). For children reported to watch television for 4-8 hours per week at age 3 the adjusted odds ratio for obesity at age 7 was 1.37 (1.02 to 1.83). For those reported to watch more than eight hours per week the adjusted odds ratio was 1.55 (1.13 to 2.12).
Dietary patterns We found no conclusive evidence of an association between dietary patterns at age 3 and risk of obesity at age 7. A junk food type dietary pattern at age 3 was significantly associated with risk of obesity at age 7, although the association only just reached significance at the 10% level in the final model (table 2).
Risk factors in children in focus subsample
The prevalence of obesity at 7 years in the children in focus subsample was not significantly different from that in the entire cohort (8.7%; 79/909). Children in the highest quarter for weight (standard deviation scores) at age 8 months and 18 months were more likely to be obese at age 7 than children in the lower quarters (table 3). Early adiposity or body mass index rebound, catch-up growth between birth and two years, and high rates of weight gain in the first 12 months were also independently associated with obesity at age 7 (table 3).
Table 3 Associations between four risk factors and obesity at age 7 years in children in focus subsample. Values are numbers (percentages) unless stated otherwise
Discussion
Reilly JJ, Dorosty AR. Epidemic of obesity in UK children. Lancet 1999;354: 1874-5.
Reilly JJ, Methven E, McDowell ZC, Hacking B, Alexander D, Stewart L, et al. Health consequences of obesity. Arch Dis Child 2003;88: 748-52.
Dietz WH. Birth weight, socioeconomic class, and adult adiposity among African Americans. Am J Clin Nutr 2000;72: 335-6.
Dietz WH. Breastfeeding may help prevent childhood overweight. JAMA 2001;285: 2506-7.
Parsons TJ, Power C, Summerbell CD. Childhood predictors of adult obesity: systematic review. Int J Obes 1999;23 (suppl 8): S1-107.
Golding J, Pembrey M, Jones R, ALSPAC Study Team. ALSPAC-the Avon longitudinal study of parents and children I: study methodology. Paediatr Perinat Epidemiol 2001;15: 74-87.
Cole TJ, Freeman JV, Preece MA. Body mass index reference curves for the UK, 1990. Arch Dis Child 1995;73: 25-9.
Reilly J, Dorosty AR, Emmett PM, ALSPAC Study Team. Identification of the obese child: adequacy of the BMI for clinical practice and epidemiology. Int J Obes 2000;24: 1623-7.
Reilly JJ, Wilson ML, Summerbell CD, Wilson AC. Obesity: diagnosis, prevention, and treatment; evidence based answers to common questions. Arch Dis Child 2002;86: 392-4.
North K, Emmett P, ALSPAC Study Team. Multivariate analysis of diet among three-year-old children and associations with socio-demographic characteristics. Eur J Clin Nutr 2001;54: 73-80.
Whitaker RC. Obesity prevention in primary care: four behaviors to target. Arch Pediatr Adolesc Med 2003;157: 725-7.
Armstrong J, Reilly JJ. Child Health Information Team. Breastfeeding and lowering the risk of childhood obesity. Lancet 2002;359: 2003-4.
Bogen DL, Hanusa BH, Whitaker RC. The effect of breastfeeding with and without concurrent formula feeding on risk of obesity at 4 years of age. Obes Res 2004;12: 1527-35.
Von Kries R, Toschke AM, Koletzko B, Slikker W Jr. Maternal smoking during pregnancy and childhood obesity. Am J Epidemiol 2002;156: 954-61.
Grove KL, Sekhon HS, Brogan RS, Keller JA, Smith MS, Spindel ER. Chronic maternal nicotine exposure alters neuronal systems in the arcuate nucleus that regulate feeding behavior in the newborn rhesus macaque. J Clin Endocrinol Metab 2001;86: 5420-6.
Dorosty AR, Emmett PM, Reilly JJ, ALSPAC Study Team. Factors associated with early adiposity rebound. Pediatrics 2000;105: 1115-8.
Francis LA, Lee Y, Birch LL. Parental weight status and girls television viewing, snacking, and body mass indexes. Obes Res 2003;11: 143-51.
Gortmaker SL, Must A, Sobol AM, Petgerson K, Colditz GA, Dietz WH. Television viewing as a cause of increasing obesity among children in the United States 1986-1990. Arch Pediatr Adolesc Med 1996;150: 356-62.
Robinson TN. Reducing children's television viewing to prevent obesity: randomized controlled trial. JAMA 1999;282: 1561-7.
Stettler N, Zemel BS, Kumanyika S, Stallings VA. Infant weight gain and childhood overweight status in a multicenter cohort study. Pediatrics 2002;109: 194-9.
Ong KK, Ahmed ML, Emmett PM, Preece MA, Dunger DB. Association between postnatal catch-up growth and obesity in childhood: prospective cohort study. BMJ 2000;320: 967-71.
Birch LL, Fisher JO. Development of eating behaviors among children and adolescents. Pediatrics 1998;101: 539-49.
Dabelea D, Hanson RL, Lindsay RS, Pettitt DJ, Imperatore G, Gabir MM, et al. Intrauterine exposure to diabetes conveys risks for type 2 diabetes and obesity: a study of discordant sibships. Diabetes 2000;49: 2208-11.
Dietz WH. Periods of risk in childhood for the development of adult obesity—what do we need to learn? J Nutr 1997;127(suppl 4): S1884-6.(John J Reilly, reader in paediatric ener)