In a nationally representative cohort of 5362 children born in one week in March 1946 weights and heights were recorded at 6, 7, 11, 14, 20, and 26 years. Overweight was defined as a weight that exceeded the standard weight for height, age, and sex by more than 20% (relative weight > 120%). The prevalence of overweight was 1-7% and 2 9% in boys and girls respectively at 6 years; 2 0% and 3 8% at 7 years; 64% and 9-6% at 11 years; 6-5% and 9 6% at 14 years; 54% and 6 5% at 20 years; and 12-3% and 11-2% at 26 years. The risk of being overweight in adulthood was related to the degree of overweight in childhood and was about four in 10 for overweight 7-year-olds. Analysis of the data in the reverse direction showed that 7% and 13% respectively of 26-year-old overweight men and women had been overweight at the age of 7.These results suggest that there is no optimal age during childhood for the prediction of overweight in adult life and that excessive weight gain may begin at any time. Overweight children are more likely to remain overweight than their contemporaries of normal weight are to become overweight.

In girls, menarche is an indicator of pubertal timing but the mechanism that controls the onset of puberty and triggers menarche is not known. It has been suggested that early menarche in obese girls may be due to overweight resulting from overeating.6 7 Some studies do not support this hypothesis, however, and the association between overweight and menarche remains unclear.8Using data derived from the National Child Development Study,9 we describe the association between age at menarche and relative weight (weight adjusted for height) and estimate the incidence of early menarche in girls who were overweight and underweight at 7 and 11 years of age. As the data are longitudinal it was also possible to relate age at menarche to birth weight and to changes in relative weight between the ages of 7 and 11 years. The hypothesisl' that nutrition plays a leading role in the timing of the menarche is discussed in the light of the findings of the study. MethodThe National Child Development Study (NCDS) is a longitudinal follow up study of all children in England, Scotland, and Wales who were born in one week in March 1958. The original cohort of nearly 17 000 was studied at birth and again at the ages of 7, 11, and 16 years. Information on health, education, family, and socioeconomic class was collected at each follow up visit. At the medical examination when they were 16 years old, girls were asked at what age they had first menstruated. Of those who responded, 4427 had had their weight and height measured when they were 16, 3653 when they were 7, and 3675 when they were 11 years old. Complete information on age at menarche and weight and height at 7, 11, and 16 years of age was available for 3018 girls. The analysis of response rates and the assessment of expected weight for height have been previously described."1 Relative weight, which is observed weight expressed as a percentage of the weight expected from a regression of log weight on log height, was calculated for each girl at each age. This assumes that expected weight=c(height)P, where c and p are constants. Overweight was defined as weight that exceeded the expected weight by 20% (relative weight more than 120). In the previous study of prevalence of overweight" children from 383 on 10 May 2018 by guest. Protected by copyright.

Study objective-The purpose of this study was to investigate the relation between blood pressure at age 36, and birth weight and body mass index (BMI) in childhood, adolescence and adulthood. Design-Prospective longitudinal survey over a period of 36 years in England, Scotland, and Wales.Participants-A nationally representative sample consisting of 3332 men and women born in one week in March 1946. Altogether 82% of these subjects had complete data for the present analysis. Main results-There was an inverse linear relation between birth weight and blood pressure at age 36. The relation between BMI and blood pressure at age 36 was initially inverse and became increasingly positive throughout life. Weight gain in childhood was positively associated with adult blood pressure, although less important than weight change in later life. The associations between blood pressure and birth weight, and blood pressure and adult BMI were independent, and together they accounted for no more than 4% of the variation in adult blood pressure. Both low birth weight (birth weight s2-5kg) and high BMI at age 36 (BMI >30kg/m2) were associated with hypertension (> 140/9OmmHg), but the per cent population risk of hypertension attributable to low birth weight was less than 5%, and to high BMI less than 12%. Conclusions-Low birth weight and high BMI at age 36 were independently related to high blood pressure. A reduction in the percentage of low birthweight babies born in the fourth decade ofthis century would only have a negligible effect on the incidence of adult hypertension 30-40 years later.

The prevalence of overweight at ages 7 and 11 years and in late adolescence was compared in two nationally representative cohorts of British children born in 1946 and 1958. Overweight was defined as weight that exceeded the standard weight for height, age, and sex by more than 20% (relative weight > 120%). The prevalence of overweight among 7 year olds born in 1958 was nearly twice that among those born in 1946. Changes in infant feeding practices, food supply, and level of physical activity might be responsible for this difference. By adolescence the prevalence of obesity in both cohorts had increased but the difference between cohorts had almost disappeared. Around 9% of adolescent girls and 7% of adolescent boys were overweight. If infant feeding practices have an influence on prevalence of overweight at 7 years the data from the two cohorts suggest that such an effect does not persist. In neither cohort was there a significant relation between the prevalence of obesity and social class in boys, but in girls the prevalence was higher among those from the lower socioeconomic groups. Correlation coefficients showing the strength of the relation between relative weights at different ages were remarkably similar for both cohorts. The risk of being obese later in childhood for those who had not been obese at the age of 7 was less than one in 10, whereas for those with a relative weight greater than 130% the risk exceeded six in 10.

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