Tracking relative weight in subjects studied longitudinally from ages 3 to 13 years

Heights and weights of a large sample of subjects studied longitudinally from ages 3 and 13 years were used to calculate relative weight, using a Body Mass Index score (BMI) which estimates adiposity. Males and females differed significantly in BMI scores only at ages 3 and 13 years. The correlations between BMI scores at all ages were positive and significant. The subjects were divided at each age into a 'light', an 'average' and a 'heavy' group based on the position of their BMI score relative to the 25th and 75th percentiles. Subjects were 'tracked' from ages 3, 7 and 11 years to determine whether they had remained in the same BMI group by age 13 years relative to their peers. Slightly fewer than half of the 3 year old subjects but the majority of 7 and 11 year old subjects remained in the same relative weight group by age 13 years. Only 1% of 7 and 11 year old subjects in the top and the bottom quartiles for BMI scores shifted from one extreme group to the other. Relative weight at 3, 7 and 11 years was more persistent for subjects with extreme bodyweights than subjects with bodyweights in the middle range. Consistent with the pattern of correlations, the tracking pattern for all 3 groups showed that subjects' BMI scores remained more stable as the subjects grew older.     

A longitudinal study of the interactive effects of perinatal complications and early family adversity on cognitive ability

Abstract The effects of high, medium and low levels of perinatal complications and family adversity on intelligence quotient (IQ) scores were examined in a large sample of Dunedin children tested every second year in the age group 3–13 years. The aim was to test the hypothesis that favourable environmental circumstances attenuate the effects of perinatal complications on later cognitive ability. The results did not support this hypothesis but rather suggested that perinatal complications and family adversity have independent adverse effects on the development of children's cognitive ability.     

Growth and development of twins compared with singletons at ages five and seven: A follow-up report from the Dunedin Multidisciplinary Child Development Study

ABSTRACT. The growth and development of 24 twins at ages five and seven years were compared with a large group of Dunedin singletons. The physical growth and intelligence of the twins were found to remain disadvantaged at ages five and seven but language development and reading did not differ significantly from that of singletons.