Abstract
This thesis was based on data from the Dunedin Multidisciplinary Health and Development Study (DMHDS). The DMHDS is a birth cohort of around 1000 individuals, born in Dunedin, New Zealand between April 1972 and March 1973. Included in the three studies presented here was information obtained during assessments at birth and ages 3, 5, 7, 9, 11, 13, 15, 18,21 and 26 years.